5th year of living dangerously with LiFePo4 batteries

[jfitch]

Got it at the beginning of the 2014 season, 12AH Starkpower. Last year I got the CBA battery tester. At the beginning of last year it tested at 11.908 AH (down to 11 V) at a 1.5A load. Just tested it again and got 11.820AH. My panel is drawing about 1.3A if I don't turn on the solar charger, so I'm limited to 9 hour flights. It would be 14 hours with the solar, but of course the sun is gone by then. Oh well.

I've had 12AH AGMs made by Panasonic and others last about 3 seasons at most, best to replace them after 2, and generally they would be below 11.5 volts by the end of the 6 hour day even in the first season.

Now I know I take my life into my hands every time I load the LFP into the glider, but I intend to continue taking the risk.

[krasw]

On Sunday, 3 June 2018 08:20:42 UTC+3, jfitch wrote:
> Got it at the beginning of the 2014 season, 12AH Starkpower. Last year I got the CBA battery tester. At the beginning of last year it tested at 11.908 AH (down to 11 V) at a 1.5A load. Just tested it again and got 11.820AH. My panel is drawing about 1.3A if I don't turn on the solar charger, so I'm limited to 9 hour flights. It would be 14 hours with the solar, but of course the sun is gone by then. Oh well.
>
> I've had 12AH AGMs made by Panasonic and others last about 3 seasons at most, best to replace them after 2, and generally they would be below 11.5 volts by the end of the 6 hour day even in the first season.
>
> Now I know I take my life into my hands every time I load the LFP into the glider, but I intend to continue taking the risk.

Last week there was (to my knowledge) first case of LFPs catching fire in glider. Luckily the glider was close to airfield and landed immediately. Primary structures were not damaged but it was a matter of minute or two, and pilots considered using parachutes. I thought LFPs were pretty safe but now we know better.

[Renny[_2_]]

On Sunday, June 3, 2018 at 6:48:44 AM UTC-6, krasw wrote:
> On Sunday, 3 June 2018 08:20:42 UTC+3, jfitch wrote:
> > Got it at the beginning of the 2014 season, 12AH Starkpower. Last year I got the CBA battery tester. At the beginning of last year it tested at 11..908 AH (down to 11 V) at a 1.5A load. Just tested it again and got 11.820AH. My panel is drawing about 1.3A if I don't turn on the solar charger, so I'm limited to 9 hour flights. It would be 14 hours with the solar, but of course the sun is gone by then. Oh well.
> >
> > I've had 12AH AGMs made by Panasonic and others last about 3 seasons at most, best to replace them after 2, and generally they would be below 11.5 volts by the end of the 6 hour day even in the first season.
> >
> > Now I know I take my life into my hands every time I load the LFP into the glider, but I intend to continue taking the risk.
>
> Last week there was (to my knowledge) first case of LFPs catching fire in glider. Luckily the glider was close to airfield and landed immediately. Primary structures were not damaged but it was a matter of minute or two, and pilots considered using parachutes. I thought LFPs were pretty safe but now we know better.

Interesting...I am very glad they landed safely. Can you tell us where this event occurred?

[kinsell]

On 06/03/2018 06:48 AM, krasw wrote:
> On Sunday, 3 June 2018 08:20:42 UTC+3, jfitch wrote:
>> Got it at the beginning of the 2014 season, 12AH Starkpower. Last year I got the CBA battery tester. At the beginning of last year it tested at 11.908 AH (down to 11 V) at a 1.5A load. Just tested it again and got 11.820AH. My panel is drawing about 1.3A if I don't turn on the solar charger, so I'm limited to 9 hour flights. It would be 14 hours with the solar, but of course the sun is gone by then. Oh well.
>>
>> I've had 12AH AGMs made by Panasonic and others last about 3 seasons at most, best to replace them after 2, and generally they would be below 11.5 volts by the end of the 6 hour day even in the first season.
>>
>> Now I know I take my life into my hands every time I load the LFP into the glider, but I intend to continue taking the risk.
>
> Last week there was (to my knowledge) first case of LFPs catching fire in glider. Luckily the glider was close to airfield and landed immediately. Primary structures were not damaged but it was a matter of minute or two, and pilots considered using parachutes. I thought LFPs were pretty safe but now we know better.
>

"We" know better? Be careful about including Jon in that, he's made
quite a career out of trying to convince people to use lithium.

Do people really think they're that foolproof? Are you guys not
familiar with Google and YouTube?


http://www.batteryvehiclesociety.org.uk/bvsorguk/forums/viewtopic.php?t=1825

[Dan Marotta]

Just for balance, has there ever been an inflight fire with a lead-acid
battery?Â* I can't find an instance with a quick google search.

On 6/3/2018 7:50 AM, kinsell wrote:
> On 06/03/2018 06:48 AM, krasw wrote:
>> On Sunday, 3 June 2018 08:20:42 UTC+3, jfitchÂ* wrote:
>>> Got it at the beginning of the 2014 season, 12AH Starkpower. Last
>>> year I got the CBA battery tester. At the beginning of last year it
>>> tested at 11.908 AH (down to 11 V) at a 1.5A load. Just tested it
>>> again and got 11.820AH. My panel is drawing about 1.3A if I don't
>>> turn on the solar charger, so I'm limited to 9 hour flights. It
>>> would be 14 hours with the solar, but of course the sun is gone by
>>> then. Oh well.
>>>
>>> I've had 12AH AGMs made by Panasonic and others last about 3 seasons
>>> at most, best to replace them after 2, and generally they would be
>>> below 11.5 volts by the end of the 6 hour day even in the first season.
>>>
>>> Now I know I take my life into my hands every time I load the LFP
>>> into the glider, but I intend to continue taking the risk.
>>
>> Last week there was (to my knowledge) first case of LFPs catching
>> fire in glider. Luckily the glider was close to airfield and landed
>> immediately. Primary structures were not damaged but it was a matter
>> of minute or two, and pilots considered using parachutes. I thought
>> LFPs were pretty safe but now we know better.
>>
>
> "We" know better?Â* Be careful about including Jon in that, he's made
> quite a career out of trying to convince people to use lithium.
>
> Do people really think they're that foolproof?Â* Are you guys not
> familiar with Google and YouTube?
>
>
> http://www.batteryvehiclesociety.org.uk/bvsorguk/forums/viewtopic.php?t=1825
>

--
Dan, 5J

[jfitch]

To correct the record, I have not "made a career out of convincing people" to do anything. I've reported my experience, and corrected errors of fact. You use what you like - my career is not furthered either way. In the same link you provided, is a further link to another electric car also burned to a crisp, but using LA batteries to do it.

Any battery of 10 AH size can start a nice fire. I can start a fire with a 1.5V D cell, it isn't hard.

I'd like to know more specifics about the incident krasw mentioned.

On Sunday, June 3, 2018 at 6:51:29 AM UTC-7, kinsell wrote:
> On 06/03/2018 06:48 AM, krasw wrote:
> > On Sunday, 3 June 2018 08:20:42 UTC+3, jfitch wrote:
> >> Got it at the beginning of the 2014 season, 12AH Starkpower. Last year I got the CBA battery tester. At the beginning of last year it tested at 11.908 AH (down to 11 V) at a 1.5A load. Just tested it again and got 11.820AH. My panel is drawing about 1.3A if I don't turn on the solar charger, so I'm limited to 9 hour flights. It would be 14 hours with the solar, but of course the sun is gone by then. Oh well.
> >>
> >> I've had 12AH AGMs made by Panasonic and others last about 3 seasons at most, best to replace them after 2, and generally they would be below 11.5 volts by the end of the 6 hour day even in the first season.
> >>
> >> Now I know I take my life into my hands every time I load the LFP into the glider, but I intend to continue taking the risk.
> >
> > Last week there was (to my knowledge) first case of LFPs catching fire in glider. Luckily the glider was close to airfield and landed immediately. Primary structures were not damaged but it was a matter of minute or two, and pilots considered using parachutes. I thought LFPs were pretty safe but now we know better.
> >
>
> "We" know better? Be careful about including Jon in that, he's made
> quite a career out of trying to convince people to use lithium.
>
> Do people really think they're that foolproof? Are you guys not
> familiar with Google and YouTube?
>
>
> http://www.batteryvehiclesociety.org.uk/bvsorguk/forums/viewtopic.php?t=1825

[Nick Kennedy]

So is the problem of a fire caused by a dead short across the battery terminals?
Shouldn't a inline fuse coming off the positive terminal take care of any fire problem? I realize a wrench or something like it placed across the terminals would cause a massive short and possible fire, but lacking that, whats the problem?
Do these things spontaneously combust? I have two in my ship and want to know.

[Richard Pfiffner[_2_]]

On Sunday, June 3, 2018 at 8:18:49 AM UTC-7, Nick Kennedy wrote:
> So is the problem of a fire caused by a dead short across the battery terminals?
> Shouldn't a inline fuse coming off the positive terminal take care of any fire problem? I realize a wrench or something like it placed across the terminals would cause a massive short and possible fire, but lacking that, whats the problem?
> Do these things spontaneously combust? I have two in my ship and want to know.

I shorted two different batteries, by placing upside down on a metal plate.

The LiFEPO4 was a non event. The battery management shut down immediately.

On the other hand the Lead Acid got quite hot melted the case.

Richard

[jfitch]

On Sunday, June 3, 2018 at 8:29:08 AM UTC-7, Richard Pfiffner wrote:
> On Sunday, June 3, 2018 at 8:18:49 AM UTC-7, Nick Kennedy wrote:
> > So is the problem of a fire caused by a dead short across the battery terminals?
> > Shouldn't a inline fuse coming off the positive terminal take care of any fire problem? I realize a wrench or something like it placed across the terminals would cause a massive short and possible fire, but lacking that, whats the problem?
> > Do these things spontaneously combust? I have two in my ship and want to know.
>
> I shorted two different batteries, by placing upside down on a metal plate.
>
> The LiFEPO4 was a non event. The battery management shut down immediately.
>
> On the other hand the Lead Acid got quite hot melted the case.
>
> Richard

There you go bringing real data into the discussion again.

I would like krasw to elaborate on the event, if he knows more. Anything that stores energy is potentially dangerous. The devil is in the details.

[Frank Whiteley]

On Sunday, June 3, 2018 at 8:15:09 AM UTC-6, Dan Marotta wrote:
> Just for balance, has there ever been an inflight fire with a lead-acid
> battery?Â* I can't find an instance with a quick google search.
>
> On 6/3/2018 7:50 AM, kinsell wrote:
> > On 06/03/2018 06:48 AM, krasw wrote:
> >> On Sunday, 3 June 2018 08:20:42 UTC+3, jfitchÂ* wrote:
> >>> Got it at the beginning of the 2014 season, 12AH Starkpower. Last
> >>> year I got the CBA battery tester. At the beginning of last year it
> >>> tested at 11.908 AH (down to 11 V) at a 1.5A load. Just tested it
> >>> again and got 11.820AH. My panel is drawing about 1.3A if I don't
> >>> turn on the solar charger, so I'm limited to 9 hour flights. It
> >>> would be 14 hours with the solar, but of course the sun is gone by
> >>> then. Oh well.
> >>>
> >>> I've had 12AH AGMs made by Panasonic and others last about 3 seasons
> >>> at most, best to replace them after 2, and generally they would be
> >>> below 11.5 volts by the end of the 6 hour day even in the first season.

[2G]

On Sunday, June 3, 2018 at 9:17:50 PM UTC-7, Frank Whiteley wrote:
> On Sunday, June 3, 2018 at 8:15:09 AM UTC-6, Dan Marotta wrote:
> > Just for balance, has there ever been an inflight fire with a lead-acid
> > battery?Â* I can't find an instance with a quick google search.
> >
> > On 6/3/2018 7:50 AM, kinsell wrote:
> > > On 06/03/2018 06:48 AM, krasw wrote:
> > >> On Sunday, 3 June 2018 08:20:42 UTC+3, jfitchÂ* wrote:
> > >>> Got it at the beginning of the 2014 season, 12AH Starkpower. Last
> > >>> year I got the CBA battery tester. At the beginning of last year it
> > >>> tested at 11.908 AH (down to 11 V) at a 1.5A load. Just tested it
> > >>> again and got 11.820AH. My panel is drawing about 1.3A if I don't
> > >>> turn on the solar charger, so I'm limited to 9 hour flights. It
> > >>> would be 14 hours with the solar, but of course the sun is gone by
> > >>> then. Oh well.
> > >>>
> > >>> I've had 12AH AGMs made by Panasonic and others last about 3 seasons
> > >>> at most, best to replace them after 2, and generally they would be
> > >>> below 11.5 volts by the end of the 6 hour day even in the first season.
> > >>>
> > >>> Now I know I take my life into my hands every time I load the LFP
> > >>> into the glider, but I intend to continue taking the risk.
> > >>
> > >> Last week there was (to my knowledge) first case of LFPs catching
> > >> fire in glider. Luckily the glider was close to airfield and landed
> > >> immediately. Primary structures were not damaged but it was a matter
> > >> of minute or two, and pilots considered using parachutes. I thought
> > >> LFPs were pretty safe but now we know better.
> > >>
> > >
> > > "We" know better?Â* Be careful about including Jon in that, he's made
> > > quite a career out of trying to convince people to use lithium.
> > >
> > > Do people really think they're that foolproof?Â* Are you guys not
> > > familiar with Google and YouTube?
> > >
> > >
> > > http://www.batteryvehiclesociety.org.uk/bvsorguk/forums/viewtopic.php?t=1825
> > >
> >
> > --
> > Dan, 5J
>
> 2-33 in Virginia a few years ago. Not a battery fire, but a wiring short to the fuselage that resulted in the fabric burning the glider being landed in trees.
>
> https://app.ntsb.gov/pdfgenerator/ReportGeneratorFile.ashx?EventID=20100801X51612&AKey=1&RType=Final&IType=LA

Here is a scientific comparison (experiment) of thermal runaway of Li-Ion batteries:
file:///C:/Users/tom_s/Downloads/batteries-03-00014.pdf
Notable is that LiFP batteries could not be provoked into thermal runaway. The reason for this is that the oxygen molecules are covalently bonded to a metal (iron) and doesn't disassociate when heated until very high temps are reached.

Tom

[[email protected]]

Ive seen SLA batteries in UPS systems swell up and catch fire, at the local recycling yard.

[kinsell]

On 06/03/2018 09:18 AM, Nick Kennedy wrote:
>
>
> So is the problem of a fire caused by a dead short across the battery terminals?

No reason to jump to an assumption like that. Fires with other lithium
chemistries have generally not involved shorts on the terminals. When
those FES gliders lit up recently, nobody was dropping wrenches on them.

Be interesting to find out what really happened with this LFP.

[krasw]

On Monday, 4 June 2018 02:01:18 UTC+3, jfitch wrote:
> On Sunday, June 3, 2018 at 8:29:08 AM UTC-7, Richard Pfiffner wrote:
> > On Sunday, June 3, 2018 at 8:18:49 AM UTC-7, Nick Kennedy wrote:
> > > So is the problem of a fire caused by a dead short across the battery terminals?
> > > Shouldn't a inline fuse coming off the positive terminal take care of any fire problem? I realize a wrench or something like it placed across the terminals would cause a massive short and possible fire, but lacking that, whats the problem?
> > > Do these things spontaneously combust? I have two in my ship and want to know.
> >
> > I shorted two different batteries, by placing upside down on a metal plate.
> >
> > The LiFEPO4 was a non event. The battery management shut down immediately.
> >
> > On the other hand the Lead Acid got quite hot melted the case.
> >
> > Richard
>
> There you go bringing real data into the discussion again.
>
> I would like krasw to elaborate on the event, if he knows more. Anything that stores energy is potentially dangerous. The devil is in the details.

So far I have no other info, battery was smoking after removed from the glider. Was it LFP cells or BMS electronics, I don't know.

[jfitch]

On Monday, June 4, 2018 at 6:55:55 AM UTC-7, krasw wrote:
> On Monday, 4 June 2018 02:01:18 UTC+3, jfitch wrote:
> > On Sunday, June 3, 2018 at 8:29:08 AM UTC-7, Richard Pfiffner wrote:
> > > On Sunday, June 3, 2018 at 8:18:49 AM UTC-7, Nick Kennedy wrote:
> > > > So is the problem of a fire caused by a dead short across the battery terminals?
> > > > Shouldn't a inline fuse coming off the positive terminal take care of any fire problem? I realize a wrench or something like it placed across the terminals would cause a massive short and possible fire, but lacking that, whats the problem?
> > > > Do these things spontaneously combust? I have two in my ship and want to know.
> > >
> > > I shorted two different batteries, by placing upside down on a metal plate.
> > >
> > > The LiFEPO4 was a non event. The battery management shut down immediately.
> > >
> > > On the other hand the Lead Acid got quite hot melted the case.
> > >
> > > Richard
> >
> > There you go bringing real data into the discussion again.
> >
> > I would like krasw to elaborate on the event, if he knows more. Anything that stores energy is potentially dangerous. The devil is in the details.
>
> So far I have no other info, battery was smoking after removed from the glider. Was it LFP cells or BMS electronics, I don't know.

Keeping score: so far we have one FAA documented fire due to an SLA battery leading to the loss of the aircraft, against a rumor of a smoking battery that may or may not have been LFP which was removed from the glider on landing without damage to it. Other lithium chemistries are irrelevant, unless you are using those in your glider (such as the FES).

[[email protected]]

I know of one glider here in Canada which burnt up while in the trailer as a result of a metal rigging aid falling onto the battery (placed in the trailer's cargo area) and shorting it out. I also had a few pictures, lost when an old hard drive died that a club member sent me of a glider that had the battery short out and burn fortunately before takeoff. Recently someone I knew improperly charged the batteries that reside under the cockpit floor of his ship and I think he's lucky that the cases didn't burst - they were swollen so much that getting them out was rather difficult. All were SLA batteries.

These incidents say more about the need to protect the battery terminal area well and include a fuse as close as possible to the terminals (a set up like the Dittel battery box for example) and use a good charger than they do about chemistry though.

[kinsell]

On 06/04/2018 09:59 AM, jfitch wrote:
> On Monday, June 4, 2018 at 6:55:55 AM UTC-7, krasw wrote:
>> On Monday, 4 June 2018 02:01:18 UTC+3, jfitch wrote:
>>> On Sunday, June 3, 2018 at 8:29:08 AM UTC-7, Richard Pfiffner wrote:
>>>> On Sunday, June 3, 2018 at 8:18:49 AM UTC-7, Nick Kennedy wrote:
>>>>> So is the problem of a fire caused by a dead short across the battery terminals?
>>>>> Shouldn't a inline fuse coming off the positive terminal take care of any fire problem? I realize a wrench or something like it placed across the terminals would cause a massive short and possible fire, but lacking that, whats the problem?
>>>>> Do these things spontaneously combust? I have two in my ship and want to know.
>>>>
>>>> I shorted two different batteries, by placing upside down on a metal plate.
>>>>
>>>> The LiFEPO4 was a non event. The battery management shut down immediately.
>>>>
>>>> On the other hand the Lead Acid got quite hot melted the case.
>>>>
>>>> Richard
>>>
>>> There you go bringing real data into the discussion again.
>>>
>>> I would like krasw to elaborate on the event, if he knows more. Anything that stores energy is potentially dangerous. The devil is in the details.
>>
>> So far I have no other info, battery was smoking after removed from the glider. Was it LFP cells or BMS electronics, I don't know.
>
> Keeping score: so far we have one FAA documented fire due to an SLA battery leading to the loss of the aircraft, against a rumor of a smoking battery that may or may not have been LFP which was removed from the glider on landing without damage to it. Other lithium chemistries are irrelevant, unless you are using those in your glider (such as the FES).
>

Wow! Did you read a different report than I did? What I saw was from
the NTSB (the folks who do the investigations), it used the term "gell
cell" instead of SLA, and most importantly it assigned no blame to the
battery. It said there was enough fire damage that they couldn't
determine if there was arcing on the terminals. They did find signs of
arcing on the wiring. That's quite a jump to calling it a "fire due to
an SLA battery", isn't it?

Apparently a "rumor" is something you don't want to believe, and a
"fact" is something you do.

[jfitch]

On Tuesday, June 5, 2018 at 7:08:03 AM UTC-7, kinsell wrote:
> On 06/04/2018 09:59 AM, jfitch wrote:
> > On Monday, June 4, 2018 at 6:55:55 AM UTC-7, krasw wrote:
> >> On Monday, 4 June 2018 02:01:18 UTC+3, jfitch wrote:
> >>> On Sunday, June 3, 2018 at 8:29:08 AM UTC-7, Richard Pfiffner wrote:
> >>>> On Sunday, June 3, 2018 at 8:18:49 AM UTC-7, Nick Kennedy wrote:
> >>>>> So is the problem of a fire caused by a dead short across the battery terminals?
> >>>>> Shouldn't a inline fuse coming off the positive terminal take care of any fire problem? I realize a wrench or something like it placed across the terminals would cause a massive short and possible fire, but lacking that, whats the problem?
> >>>>> Do these things spontaneously combust? I have two in my ship and want to know.
> >>>>
> >>>> I shorted two different batteries, by placing upside down on a metal plate.
> >>>>
> >>>> The LiFEPO4 was a non event. The battery management shut down immediately.
> >>>>
> >>>> On the other hand the Lead Acid got quite hot melted the case.
> >>>>
> >>>> Richard
> >>>
> >>> There you go bringing real data into the discussion again.
> >>>
> >>> I would like krasw to elaborate on the event, if he knows more. Anything that stores energy is potentially dangerous. The devil is in the details.
> >>
> >> So far I have no other info, battery was smoking after removed from the glider. Was it LFP cells or BMS electronics, I don't know.
> >
> > Keeping score: so far we have one FAA documented fire due to an SLA battery leading to the loss of the aircraft, against a rumor of a smoking battery that may or may not have been LFP which was removed from the glider on landing without damage to it. Other lithium chemistries are irrelevant, unless you are using those in your glider (such as the FES).
> >
>
> Wow! Did you read a different report than I did? What I saw was from
> the NTSB (the folks who do the investigations), it used the term "gell
> cell" instead of SLA, and most importantly it assigned no blame to the
> battery. It said there was enough fire damage that they couldn't
> determine if there was arcing on the terminals. They did find signs of
> arcing on the wiring. That's quite a jump to calling it a "fire due to
> an SLA battery", isn't it?
>
> Apparently a "rumor" is something you don't want to believe, and a
> "fact" is something you do.

A couple of facts: A gel battery IS an SLA battery. Its I/V characteristics and chemistry are substantially identical to an AGM, which is also an SLA battery. The only difference is in how the acid is immobilized. Second fact, a battery - any battery - does not spontaneously combust. If they do so, it is while being charged or discharged, usually under out-of-spec circumstances. Another fact: most electrical fires are caused by faults in wiring. Some further facts: the incident in question was caused without question by the SLA battery. It was an electrical fire which would not have occurred had the battery not been present, and therefore a proximate cause. A fact that you will find very inconvenient: had that battery been a properly constructed LFP, the incident would not have occurred. As Richard has pointed out above, the BMS would simply have disconnected the output and the glider would have landed without incident. For mitigation of wiring faults (by far the highest cause of electrical fires) an LFP is much safer than an SLA battery, which has no such protections.

Once again, you can use whatever battery you like, but you don't get to use "alternative facts".

And finally, I do believe in facts, and I don't (necessarily) believe in rumors.

[K m]

On Tuesday, June 5, 2018 at 9:55:30 AM UTC-6, jfitch wrote:
> On Tuesday, June 5, 2018 at 7:08:03 AM UTC-7, kinsell wrote:
> > On 06/04/2018 09:59 AM, jfitch wrote:
> > > On Monday, June 4, 2018 at 6:55:55 AM UTC-7, krasw wrote:
> > >> On Monday, 4 June 2018 02:01:18 UTC+3, jfitch wrote:
> > >>> On Sunday, June 3, 2018 at 8:29:08 AM UTC-7, Richard Pfiffner wrote:
> > >>>> On Sunday, June 3, 2018 at 8:18:49 AM UTC-7, Nick Kennedy wrote:
> > >>>>> So is the problem of a fire caused by a dead short across the battery terminals?
> > >>>>> Shouldn't a inline fuse coming off the positive terminal take care of any fire problem? I realize a wrench or something like it placed across the terminals would cause a massive short and possible fire, but lacking that, whats the problem?
> > >>>>> Do these things spontaneously combust? I have two in my ship and want to know.
> > >>>>
> > >>>> I shorted two different batteries, by placing upside down on a metal plate.
> > >>>>
> > >>>> The LiFEPO4 was a non event. The battery management shut down immediately.
> > >>>>
> > >>>> On the other hand the Lead Acid got quite hot melted the case.
> > >>>>
> > >>>> Richard
> > >>>
> > >>> There you go bringing real data into the discussion again.
> > >>>
> > >>> I would like krasw to elaborate on the event, if he knows more. Anything that stores energy is potentially dangerous. The devil is in the details.
> > >>
> > >> So far I have no other info, battery was smoking after removed from the glider. Was it LFP cells or BMS electronics, I don't know.
> > >
> > > Keeping score: so far we have one FAA documented fire due to an SLA battery leading to the loss of the aircraft, against a rumor of a smoking battery that may or may not have been LFP which was removed from the glider on landing without damage to it. Other lithium chemistries are irrelevant, unless you are using those in your glider (such as the FES).
> > >
> >
> > Wow! Did you read a different report than I did? What I saw was from
> > the NTSB (the folks who do the investigations), it used the term "gell
> > cell" instead of SLA, and most importantly it assigned no blame to the
> > battery. It said there was enough fire damage that they couldn't
> > determine if there was arcing on the terminals. They did find signs of
> > arcing on the wiring. That's quite a jump to calling it a "fire due to
> > an SLA battery", isn't it?
> >
> > Apparently a "rumor" is something you don't want to believe, and a
> > "fact" is something you do.
>
> A couple of facts: A gel battery IS an SLA battery. Its I/V characteristics and chemistry are substantially identical to an AGM, which is also an SLA battery. The only difference is in how the acid is immobilized. Second fact, a battery - any battery - does not spontaneously combust. If they do so, it is while being charged or discharged, usually under out-of-spec circumstances. Another fact: most electrical fires are caused by faults in wiring.. Some further facts: the incident in question was caused without question by the SLA battery. It was an electrical fire which would not have occurred had the battery not been present, and therefore a proximate cause. A fact that you will find very inconvenient: had that battery been a properly constructed LFP, the incident would not have occurred. As Richard has pointed out above, the BMS would simply have disconnected the output and the glider would have landed without incident. For mitigation of wiring faults (by far the highest cause of electrical fires) an LFP is much safer than an SLA battery, which has no such protections.
>
> Once again, you can use whatever battery you like, but you don't get to use "alternative facts".
>
> And finally, I do believe in facts, and I don't (necessarily) believe in rumors.

Fitchy, Here is a "Fact" you may find inconvenient, You could stand to lighten up;). An electrical fire in ANY glider with a battery installed would not occur if it were not present (Laughing), now would it? Whats your point? Granted they guy got the name a little mixed up (AGM, SLA, Gel Cel, whatever) but a proper SLA or AMG installation is as safe as anything out there. Why do you think auto manufacturers have been putting terminal covers on batteries for the past 30 years or so? Post crash fire protection.

Kirk

And finally, I believe in facts, but I also like rumors, innuendo, wives tales urban legends, hoaxes, and a lot of the stuff on RAS.

[Frank Whiteley]

On Tuesday, June 5, 2018 at 12:21:08 PM UTC-6, K m wrote:
> On Tuesday, June 5, 2018 at 9:55:30 AM UTC-6, jfitch wrote:
> > On Tuesday, June 5, 2018 at 7:08:03 AM UTC-7, kinsell wrote:
> > > On 06/04/2018 09:59 AM, jfitch wrote:
> > > > On Monday, June 4, 2018 at 6:55:55 AM UTC-7, krasw wrote:
> > > >> On Monday, 4 June 2018 02:01:18 UTC+3, jfitch wrote:
> > > >>> On Sunday, June 3, 2018 at 8:29:08 AM UTC-7, Richard Pfiffner wrote:
> > > >>>> On Sunday, June 3, 2018 at 8:18:49 AM UTC-7, Nick Kennedy wrote:
> > > >>>>> So is the problem of a fire caused by a dead short across the battery terminals?
> > > >>>>> Shouldn't a inline fuse coming off the positive terminal take care of any fire problem? I realize a wrench or something like it placed across the terminals would cause a massive short and possible fire, but lacking that, whats the problem?
> > > >>>>> Do these things spontaneously combust? I have two in my ship and want to know.
> > > >>>>
> > > >>>> I shorted two different batteries, by placing upside down on a metal plate.
> > > >>>>
> > > >>>> The LiFEPO4 was a non event. The battery management shut down immediately.
> > > >>>>
> > > >>>> On the other hand the Lead Acid got quite hot melted the case.
> > > >>>>
> > > >>>> Richard
> > > >>>
> > > >>> There you go bringing real data into the discussion again.
> > > >>>
> > > >>> I would like krasw to elaborate on the event, if he knows more. Anything that stores energy is potentially dangerous. The devil is in the details.
> > > >>
> > > >> So far I have no other info, battery was smoking after removed from the glider. Was it LFP cells or BMS electronics, I don't know.
> > > >
> > > > Keeping score: so far we have one FAA documented fire due to an SLA battery leading to the loss of the aircraft, against a rumor of a smoking battery that may or may not have been LFP which was removed from the glider on landing without damage to it. Other lithium chemistries are irrelevant, unless you are using those in your glider (such as the FES).
> > > >
> > >
> > > Wow! Did you read a different report than I did? What I saw was from
> > > the NTSB (the folks who do the investigations), it used the term "gell
> > > cell" instead of SLA, and most importantly it assigned no blame to the
> > > battery. It said there was enough fire damage that they couldn't
> > > determine if there was arcing on the terminals. They did find signs of
> > > arcing on the wiring. That's quite a jump to calling it a "fire due to
> > > an SLA battery", isn't it?
> > >
> > > Apparently a "rumor" is something you don't want to believe, and a
> > > "fact" is something you do.
> >
> > A couple of facts: A gel battery IS an SLA battery. Its I/V characteristics and chemistry are substantially identical to an AGM, which is also an SLA battery. The only difference is in how the acid is immobilized. Second fact, a battery - any battery - does not spontaneously combust. If they do so, it is while being charged or discharged, usually under out-of-spec circumstances. Another fact: most electrical fires are caused by faults in wiring. Some further facts: the incident in question was caused without question by the SLA battery. It was an electrical fire which would not have occurred had the battery not been present, and therefore a proximate cause. A fact that you will find very inconvenient: had that battery been a properly constructed LFP, the incident would not have occurred. As Richard has pointed out above, the BMS would simply have disconnected the output and the glider would have landed without incident. For mitigation of wiring faults (by far the highest cause of electrical fires) an LFP is much safer than an SLA battery, which has no such protections.
> >
> > Once again, you can use whatever battery you like, but you don't get to use "alternative facts".
> >
> > And finally, I do believe in facts, and I don't (necessarily) believe in rumors.
>
> Fitchy, Here is a "Fact" you may find inconvenient, You could stand to lighten up;). An electrical fire in ANY glider with a battery installed would not occur if it were not present (Laughing), now would it? Whats your point? Granted they guy got the name a little mixed up (AGM, SLA, Gel Cel, whatever) but a proper SLA or AMG installation is as safe as anything out there.. Why do you think auto manufacturers have been putting terminal covers on batteries for the past 30 years or so? Post crash fire protection.
>
> Kirk
>
> And finally, I believe in facts, but I also like rumors, innuendo, wives tales urban legends, hoaxes, and a lot of the stuff on RAS.

Sadly, not entirely unrelated to this thread. This was the plane used in the recent glider tow.

https://electrek.co/2018/06/04/siemens-electric-plane-prototype-fire-crash-death/

Frank Whiteley

[Martin Gregorie[_6_]]

On Tue, 05 Jun 2018 11:42:49 -0700, Frank Whiteley wrote:

> Sadly, not entirely unrelated to this thread. This was the plane used
> in the recent glider tow.
>
> https://electrek.co/2018/06/04/siemens-electric-plane-prototype-fire-
crash-death/
>
>

A few years back there were a lot of cheap LiIon batteries on sale as SLA
replacements that turned out not to have a BMS system - just cells in the
case. Obviously, these would be at least as flammable as an SLA of
accidentally shorted.

IIRC these were impossible to distinguish from batteries with a proper BMS
inside the case, so, are they still around and being sold to the unwary?


--
Martin | martin at
Gregorie | gregorie dot org

[jfitch]

On Tuesday, June 5, 2018 at 11:21:08 AM UTC-7, K m wrote:
> On Tuesday, June 5, 2018 at 9:55:30 AM UTC-6, jfitch wrote:
> > On Tuesday, June 5, 2018 at 7:08:03 AM UTC-7, kinsell wrote:
> > > On 06/04/2018 09:59 AM, jfitch wrote:
> > > > On Monday, June 4, 2018 at 6:55:55 AM UTC-7, krasw wrote:
> > > >> On Monday, 4 June 2018 02:01:18 UTC+3, jfitch wrote:
> > > >>> On Sunday, June 3, 2018 at 8:29:08 AM UTC-7, Richard Pfiffner wrote:
> > > >>>> On Sunday, June 3, 2018 at 8:18:49 AM UTC-7, Nick Kennedy wrote:
> > > >>>>> So is the problem of a fire caused by a dead short across the battery terminals?
> > > >>>>> Shouldn't a inline fuse coming off the positive terminal take care of any fire problem? I realize a wrench or something like it placed across the terminals would cause a massive short and possible fire, but lacking that, whats the problem?
> > > >>>>> Do these things spontaneously combust? I have two in my ship and want to know.
> > > >>>>
> > > >>>> I shorted two different batteries, by placing upside down on a metal plate.
> > > >>>>
> > > >>>> The LiFEPO4 was a non event. The battery management shut down immediately.
> > > >>>>
> > > >>>> On the other hand the Lead Acid got quite hot melted the case.
> > > >>>>
> > > >>>> Richard
> > > >>>
> > > >>> There you go bringing real data into the discussion again.
> > > >>>
> > > >>> I would like krasw to elaborate on the event, if he knows more. Anything that stores energy is potentially dangerous. The devil is in the details.
> > > >>
> > > >> So far I have no other info, battery was smoking after removed from the glider. Was it LFP cells or BMS electronics, I don't know.
> > > >
> > > > Keeping score: so far we have one FAA documented fire due to an SLA battery leading to the loss of the aircraft, against a rumor of a smoking battery that may or may not have been LFP which was removed from the glider on landing without damage to it. Other lithium chemistries are irrelevant, unless you are using those in your glider (such as the FES).
> > > >
> > >
> > > Wow! Did you read a different report than I did? What I saw was from
> > > the NTSB (the folks who do the investigations), it used the term "gell
> > > cell" instead of SLA, and most importantly it assigned no blame to the
> > > battery. It said there was enough fire damage that they couldn't
> > > determine if there was arcing on the terminals. They did find signs of
> > > arcing on the wiring. That's quite a jump to calling it a "fire due to
> > > an SLA battery", isn't it?
> > >
> > > Apparently a "rumor" is something you don't want to believe, and a
> > > "fact" is something you do.
> >
> > A couple of facts: A gel battery IS an SLA battery. Its I/V characteristics and chemistry are substantially identical to an AGM, which is also an SLA battery. The only difference is in how the acid is immobilized. Second fact, a battery - any battery - does not spontaneously combust. If they do so, it is while being charged or discharged, usually under out-of-spec circumstances. Another fact: most electrical fires are caused by faults in wiring. Some further facts: the incident in question was caused without question by the SLA battery. It was an electrical fire which would not have occurred had the battery not been present, and therefore a proximate cause. A fact that you will find very inconvenient: had that battery been a properly constructed LFP, the incident would not have occurred. As Richard has pointed out above, the BMS would simply have disconnected the output and the glider would have landed without incident. For mitigation of wiring faults (by far the highest cause of electrical fires) an LFP is much safer than an SLA battery, which has no such protections.
> >
> > Once again, you can use whatever battery you like, but you don't get to use "alternative facts".
> >
> > And finally, I do believe in facts, and I don't (necessarily) believe in rumors.
>
> Fitchy, Here is a "Fact" you may find inconvenient, You could stand to lighten up;). An electrical fire in ANY glider with a battery installed would not occur if it were not present (Laughing), now would it? Whats your point? Granted they guy got the name a little mixed up (AGM, SLA, Gel Cel, whatever) but a proper SLA or AMG installation is as safe as anything out there.. Why do you think auto manufacturers have been putting terminal covers on batteries for the past 30 years or so? Post crash fire protection.
>
> Kirk
>
> And finally, I believe in facts, but I also like rumors, innuendo, wives tales urban legends, hoaxes, and a lot of the stuff on RAS.

K m, I'm pretty light already :). And my point is exactly as you took it: ANY battery stores energy and is a potential hazard unless installed correctly. (The fire in this case was pre-crash, but your point is valid). The difference in risk between SLA or LFP chemistry storing the energy is quite small, if both are correctly installed. There is a valid argument that LFP (with proper BMS) is safer since the protection is inside the case - even if you directly short the terminals, it will fault and disconnect. This is not true of available SLA batteries.

For about the 10th time, I'm not evangelizing the use of a particular battery. I AM correcting errors of fact where they are publicly stated. I didn't say I didn't like rumors. I said I don't (necessarily) believe them.

While we are at it, while the electric plane crash is a tragedy and related to FES sailplanes which use similar batteries, it is unrelated to the LFP batteries used to power instruments in sailplanes. Take a look at the link provided by Tom above (you'll have to hack into his computer to get it....) or any of the many studies on this topic.

[kinsell]

On 06/05/2018 01:11 PM, Martin Gregorie wrote:
> On Tue, 05 Jun 2018 11:42:49 -0700, Frank Whiteley wrote:
>
>> Sadly, not entirely unrelated to this thread. This was the plane used
>> in the recent glider tow.
>>
>> https://electrek.co/2018/06/04/siemens-electric-plane-prototype-fire-
> crash-death/
>>
>>
>
> A few years back there were a lot of cheap LiIon batteries on sale as SLA
> replacements that turned out not to have a BMS system - just cells in the
> case. Obviously, these would be at least as flammable as an SLA of
> accidentally shorted.

Replace "at least" with "far more'. SLA's are way down at the bottom of
the list when it comes to flammability.

>
> IIRC these were impossible to distinguish from batteries with a proper BMS
> inside the case, so, are they still around and being sold to the unwary?
>
>

Not sure what a "proper" BMS board is. There are a variety of functions
that may be included, the data sheets tend to vague on what's in there.
See Wikipedia for a primer.

If the battery can disconnect itself from the terminals in the event of
excessive discharge current, too high of charging voltage, or too low
voltage on discharge, then it requires some high-current switches to do
the job. It's a dangerous assumption to think that a battery must have
those capabilities included.

[Jim White[_3_]]

Buy one with a fuse built in?

[[email protected]]

On Tuesday, June 5, 2018 at 2:42:51 PM UTC-4, Frank Whiteley wrote:
> On Tuesday, June 5, 2018 at 12:21:08 PM UTC-6, K m wrote:
> > On Tuesday, June 5, 2018 at 9:55:30 AM UTC-6, jfitch wrote:
> > > On Tuesday, June 5, 2018 at 7:08:03 AM UTC-7, kinsell wrote:
> > > > On 06/04/2018 09:59 AM, jfitch wrote:
> > > > > On Monday, June 4, 2018 at 6:55:55 AM UTC-7, krasw wrote:
> > > > >> On Monday, 4 June 2018 02:01:18 UTC+3, jfitch wrote:
> > > > >>> On Sunday, June 3, 2018 at 8:29:08 AM UTC-7, Richard Pfiffner wrote:
> > > > >>>> On Sunday, June 3, 2018 at 8:18:49 AM UTC-7, Nick Kennedy wrote:
> > > > >>>>> So is the problem of a fire caused by a dead short across the battery terminals?
> > > > >>>>> Shouldn't a inline fuse coming off the positive terminal take care of any fire problem? I realize a wrench or something like it placed across the terminals would cause a massive short and possible fire, but lacking that, whats the problem?
> > > > >>>>> Do these things spontaneously combust? I have two in my ship and want to know.
> > > > >>>>
> > > > >>>> I shorted two different batteries, by placing upside down on a metal plate.
> > > > >>>>
> > > > >>>> The LiFEPO4 was a non event. The battery management shut down immediately.
> > > > >>>>
> > > > >>>> On the other hand the Lead Acid got quite hot melted the case.
> > > > >>>>
> > > > >>>> Richard
> > > > >>>
> > > > >>> There you go bringing real data into the discussion again.
> > > > >>>
> > > > >>> I would like krasw to elaborate on the event, if he knows more. Anything that stores energy is potentially dangerous. The devil is in the details.
> > > > >>
> > > > >> So far I have no other info, battery was smoking after removed from the glider. Was it LFP cells or BMS electronics, I don't know.
> > > > >
> > > > > Keeping score: so far we have one FAA documented fire due to an SLA battery leading to the loss of the aircraft, against a rumor of a smoking battery that may or may not have been LFP which was removed from the glider on landing without damage to it. Other lithium chemistries are irrelevant, unless you are using those in your glider (such as the FES).
> > > > >
> > > >
> > > > Wow! Did you read a different report than I did? What I saw was from
> > > > the NTSB (the folks who do the investigations), it used the term "gell
> > > > cell" instead of SLA, and most importantly it assigned no blame to the
> > > > battery. It said there was enough fire damage that they couldn't
> > > > determine if there was arcing on the terminals. They did find signs of
> > > > arcing on the wiring. That's quite a jump to calling it a "fire due to
> > > > an SLA battery", isn't it?
> > > >
> > > > Apparently a "rumor" is something you don't want to believe, and a
> > > > "fact" is something you do.
> > >
> > > A couple of facts: A gel battery IS an SLA battery. Its I/V characteristics and chemistry are substantially identical to an AGM, which is also an SLA battery. The only difference is in how the acid is immobilized. Second fact, a battery - any battery - does not spontaneously combust. If they do so, it is while being charged or discharged, usually under out-of-spec circumstances. Another fact: most electrical fires are caused by faults in wiring. Some further facts: the incident in question was caused without question by the SLA battery. It was an electrical fire which would not have occurred had the battery not been present, and therefore a proximate cause. A fact that you will find very inconvenient: had that battery been a properly constructed LFP, the incident would not have occurred. As Richard has pointed out above, the BMS would simply have disconnected the output and the glider would have landed without incident. For mitigation of wiring faults (by far the highest cause of electrical fires) an LFP is much safer than an SLA battery, which has no such protections.
> > >
> > > Once again, you can use whatever battery you like, but you don't get to use "alternative facts".
> > >
> > > And finally, I do believe in facts, and I don't (necessarily) believe in rumors.
> >
> > Fitchy, Here is a "Fact" you may find inconvenient, You could stand to lighten up;). An electrical fire in ANY glider with a battery installed would not occur if it were not present (Laughing), now would it? Whats your point? Granted they guy got the name a little mixed up (AGM, SLA, Gel Cel, whatever) but a proper SLA or AMG installation is as safe as anything out there. Why do you think auto manufacturers have been putting terminal covers on batteries for the past 30 years or so? Post crash fire protection.
> >
> > Kirk
> >
> > And finally, I believe in facts, but I also like rumors, innuendo, wives tales urban legends, hoaxes, and a lot of the stuff on RAS.
>
> Sadly, not entirely unrelated to this thread. This was the plane used in the recent glider tow.
>
> https://electrek.co/2018/06/04/siemens-electric-plane-prototype-fire-crash-death/
>
> Frank Whiteley

Not entirely unrelated either - from the memoirs of Dezi Hamvas at the GBSC web site. This is about a "wet" lead-acid battery.

"On a very hot day, the Bird Dog refused to start after a long cranking. After it finally started, I made the first uneventful tow. At touchdown, the 24-volt military battery exploded between my legs right into my face. The cockpit instantly filled with white, very sour tasting, burning smoke. In a panic, I turned off the magneto and rolled out of the Bird Dog while it was still rolling. I ran to the hangar and washed my face and arms, ending up with only a minor skin rash.

While the battery was recharging, it accumulated Hydrogen gas in its chambers.
The gas vented out with a ¼� tube to the bottom of the Bird Dog. The engine
exhaust pipe was pointing right to the end of the Hydrogen exhaust tube. The spark from the backfiring engine ignited the gas, and burned all the way back to the battery. After this episode, we moved the battery to the back seat and rerouted the Hydrogen exhaust. Think about this when you have a ride in the back seat."

[Martin Gregorie[_6_]]

On Tue, 05 Jun 2018 14:35:42 -0600, kinsell wrote:

> Not sure what a "proper" BMS board is. There are a variety of functions
> that may be included, the data sheets tend to vague on what's in there.
> See Wikipedia for a primer.
>
I'd say it must have these functions:

- cell-balancing charging management
- low-voltage shut-down
- some sort of high-current limiting
This need not be expensive: I'd accept built-in replaceable fuses
and holders or solid state current limiters that temporarily
disconnect the battery when the load becomes excessive.
Neither are exactly what you'd call new technology.


> If the battery can disconnect itself from the terminals in the event of
> excessive discharge current, too high of charging voltage, or too low
> voltage on discharge, then it requires some high-current switches to do
> the job.
>
Inexpensive built-in fuses can handle that perfectly well.


--
Martin | martin at
Gregorie | gregorie dot org

[Martin Gregorie[_6_]]

On Tue, 05 Jun 2018 21:06:06 +0000, Jim White wrote:

> Buy one with a fuse built in?

Yes, but preferably one with a low voltage cut-off and cell-balancer for
charging as well.

But what I was pointing out is that a year or so back there were brands
that were very similar from the outside and (in some cases) had similar
prices. Some of these had BMS fitted and some just had cells wired to the
terminals. Often the descriptions didn't mention whether they had a BMS
or not.

What I want to know is whether this undocumented mess is still the case
or if you can now read published descriptions and know, with a fair
degree of confidence, whether there is or is not a BMS and current
limiter inside without having to chop the battery open to find out.

If the adverts now give reliable information about this, then I'll
investigate further: if not, I'll stick to SLAs for a while yet.


--
Martin | martin at
Gregorie | gregorie dot org

[jfitch]

On Tuesday, June 5, 2018 at 2:44:10 PM UTC-7, Martin Gregorie wrote:
> On Tue, 05 Jun 2018 21:06:06 +0000, Jim White wrote:
>
> > Buy one with a fuse built in?
>
> Yes, but preferably one with a low voltage cut-off and cell-balancer for
> charging as well.
>
> But what I was pointing out is that a year or so back there were brands
> that were very similar from the outside and (in some cases) had similar
> prices. Some of these had BMS fitted and some just had cells wired to the
> terminals. Often the descriptions didn't mention whether they had a BMS
> or not.
>
> What I want to know is whether this undocumented mess is still the case
> or if you can now read published descriptions and know, with a fair
> degree of confidence, whether there is or is not a BMS and current
> limiter inside without having to chop the battery open to find out.
>
> If the adverts now give reliable information about this, then I'll
> investigate further: if not, I'll stick to SLAs for a while yet.
>
>
> --
> Martin | martin at
> Gregorie | gregorie dot org

You are right to want to know what's in the box. In any case, you should have an external fuse immediately following the battery, since the BMS (if present) is unlikely to limit the current sufficient for most glider wiring. The BMS will protect against short circuited terminals, your fuse should protect the wiring you've chosen.

Another point that should be raised: in lithium polymer and some other chemistries, the BMS is essential to safely charge and discharge the battery. In an LFP, its function has more to do with protecting the cells from an early death due to undercharge, cell balance, or overcharge, than fire safety.. You can probably start one on fire by severely overcharging it, as you can do with any battery (even a flashlight D cell). Undercharging or cell balancing will result in unsatisfactory performance, rather than a fire. You can find some vendors LFP specs that tell you what the BMS does.

[2G]

On Tuesday, June 5, 2018 at 1:32:31 PM UTC-7, jfitch wrote:
> On Tuesday, June 5, 2018 at 11:21:08 AM UTC-7, K m wrote:
> > On Tuesday, June 5, 2018 at 9:55:30 AM UTC-6, jfitch wrote:
> > > On Tuesday, June 5, 2018 at 7:08:03 AM UTC-7, kinsell wrote:
> > > > On 06/04/2018 09:59 AM, jfitch wrote:
> > > > > On Monday, June 4, 2018 at 6:55:55 AM UTC-7, krasw wrote:
> > > > >> On Monday, 4 June 2018 02:01:18 UTC+3, jfitch wrote:
> > > > >>> On Sunday, June 3, 2018 at 8:29:08 AM UTC-7, Richard Pfiffner wrote:
> > > > >>>> On Sunday, June 3, 2018 at 8:18:49 AM UTC-7, Nick Kennedy wrote:
> > > > >>>>> So is the problem of a fire caused by a dead short across the battery terminals?
> > > > >>>>> Shouldn't a inline fuse coming off the positive terminal take care of any fire problem? I realize a wrench or something like it placed across the terminals would cause a massive short and possible fire, but lacking that, whats the problem?
> > > > >>>>> Do these things spontaneously combust? I have two in my ship and want to know.
> > > > >>>>
> > > > >>>> I shorted two different batteries, by placing upside down on a metal plate.
> > > > >>>>
> > > > >>>> The LiFEPO4 was a non event. The battery management shut down immediately.
> > > > >>>>
> > > > >>>> On the other hand the Lead Acid got quite hot melted the case.
> > > > >>>>
> > > > >>>> Richard
> > > > >>>
> > > > >>> There you go bringing real data into the discussion again.
> > > > >>>
> > > > >>> I would like krasw to elaborate on the event, if he knows more. Anything that stores energy is potentially dangerous. The devil is in the details.
> > > > >>
> > > > >> So far I have no other info, battery was smoking after removed from the glider. Was it LFP cells or BMS electronics, I don't know.
> > > > >
> > > > > Keeping score: so far we have one FAA documented fire due to an SLA battery leading to the loss of the aircraft, against a rumor of a smoking battery that may or may not have been LFP which was removed from the glider on landing without damage to it. Other lithium chemistries are irrelevant, unless you are using those in your glider (such as the FES).
> > > > >
> > > >
> > > > Wow! Did you read a different report than I did? What I saw was from
> > > > the NTSB (the folks who do the investigations), it used the term "gell
> > > > cell" instead of SLA, and most importantly it assigned no blame to the
> > > > battery. It said there was enough fire damage that they couldn't
> > > > determine if there was arcing on the terminals. They did find signs of
> > > > arcing on the wiring. That's quite a jump to calling it a "fire due to
> > > > an SLA battery", isn't it?
> > > >
> > > > Apparently a "rumor" is something you don't want to believe, and a
> > > > "fact" is something you do.
> > >
> > > A couple of facts: A gel battery IS an SLA battery. Its I/V characteristics and chemistry are substantially identical to an AGM, which is also an SLA battery. The only difference is in how the acid is immobilized. Second fact, a battery - any battery - does not spontaneously combust. If they do so, it is while being charged or discharged, usually under out-of-spec circumstances. Another fact: most electrical fires are caused by faults in wiring. Some further facts: the incident in question was caused without question by the SLA battery. It was an electrical fire which would not have occurred had the battery not been present, and therefore a proximate cause. A fact that you will find very inconvenient: had that battery been a properly constructed LFP, the incident would not have occurred. As Richard has pointed out above, the BMS would simply have disconnected the output and the glider would have landed without incident. For mitigation of wiring faults (by far the highest cause of electrical fires) an LFP is much safer than an SLA battery, which has no such protections.
> > >
> > > Once again, you can use whatever battery you like, but you don't get to use "alternative facts".
> > >
> > > And finally, I do believe in facts, and I don't (necessarily) believe in rumors.
> >
> > Fitchy, Here is a "Fact" you may find inconvenient, You could stand to lighten up;). An electrical fire in ANY glider with a battery installed would not occur if it were not present (Laughing), now would it? Whats your point? Granted they guy got the name a little mixed up (AGM, SLA, Gel Cel, whatever) but a proper SLA or AMG installation is as safe as anything out there. Why do you think auto manufacturers have been putting terminal covers on batteries for the past 30 years or so? Post crash fire protection.
> >
> > Kirk
> >
> > And finally, I believe in facts, but I also like rumors, innuendo, wives tales urban legends, hoaxes, and a lot of the stuff on RAS.
>
> K m, I'm pretty light already :). And my point is exactly as you took it: ANY battery stores energy and is a potential hazard unless installed correctly. (The fire in this case was pre-crash, but your point is valid). The difference in risk between SLA or LFP chemistry storing the energy is quite small, if both are correctly installed. There is a valid argument that LFP (with proper BMS) is safer since the protection is inside the case - even if you directly short the terminals, it will fault and disconnect. This is not true of available SLA batteries.
>
> For about the 10th time, I'm not evangelizing the use of a particular battery. I AM correcting errors of fact where they are publicly stated. I didn't say I didn't like rumors. I said I don't (necessarily) believe them.
>
> While we are at it, while the electric plane crash is a tragedy and related to FES sailplanes which use similar batteries, it is unrelated to the LFP batteries used to power instruments in sailplanes. Take a look at the link provided by Tom above (you'll have to hack into his computer to get it.....) or any of the many studies on this topic.

Sorry about that - try this link:

http://www.mdpi.com/2313-0105/3/2/14/htm

Tom

[kinsell]

On 06/05/2018 03:20 PM, Martin Gregorie wrote:
> On Tue, 05 Jun 2018 14:35:42 -0600, kinsell wrote:
>
>> Not sure what a "proper" BMS board is. There are a variety of functions
>> that may be included, the data sheets tend to vague on what's in there.
>> See Wikipedia for a primer.
>>
> I'd say it must have these functions:
>
> - cell-balancing charging management
> - low-voltage shut-down
> - some sort of high-current limiting
> This need not be expensive: I'd accept built-in replaceable fuses
> and holders or solid state current limiters that temporarily
> disconnect the battery when the load becomes excessive.
> Neither are exactly what you'd call new technology.
>
Not new technology, but the switch needs to handle the maximum current
that the battery can be called on to deliver. Many applications are
going to involve more than an amp or two to power a sailplane panel.



>
>> If the battery can disconnect itself from the terminals in the event of
>> excessive discharge current, too high of charging voltage, or too low
>> voltage on discharge, then it requires some high-current switches to do
>> the job.
>>
> Inexpensive built-in fuses can handle that perfectly well.
>
>
Fuses can handle the overcurrent, but disconnecting on high or low
voltage isn't going to be cheap, if the battery is rated for high current.

Richard had an interesting post a while ago, where he accidentally used
the wrong charger on an FLP, and battery was destroyed due to swelling.
So much for the idea of a BMS protecting the battery.

-Dave

[Martin Gregorie[_6_]]

On Wed, 06 Jun 2018 09:38:36 -0600, kinsell wrote:

> Richard had an interesting post a while ago, where he accidentally used
> the wrong charger on an FLP, and battery was destroyed due to swelling.
> So much for the idea of a BMS protecting the battery.
>

Using the wrong charger, or a multi-chemistry charger on the wrong
setting, can destroy any battery, regardless of its chemistry.

A BMS probably won't help here because the charger may not trip the max-
voltage switch and the charge balancer is only there to bring any cells
that are under- or over-charged into line with the rest.


--
Martin | martin at
Gregorie | gregorie dot org

[[email protected]]

One example does not prove all BMS cannot protect the battery.
I see no eveidence that Life is any more prone to failiure than SLA gell cells.

[jfitch]

On Wednesday, June 6, 2018 at 4:25:03 PM UTC-7, wrote:
> One example does not prove all BMS cannot protect the battery.
> I see no eveidence that Life is any more prone to failiure than SLA gell cells.

If we are rejecting all batteries that can be damaged by connecting to the wrong charger, then we are left with nothing. You can make an SLA explode rather dramatically doing that.

[kinsell]

On 06/05/2018 03:44 PM, Martin Gregorie wrote:
> On Tue, 05 Jun 2018 21:06:06 +0000, Jim White wrote:
>
>> Buy one with a fuse built in?
>
> Yes, but preferably one with a low voltage cut-off and cell-balancer for
> charging as well.
>
> But what I was pointing out is that a year or so back there were brands
> that were very similar from the outside and (in some cases) had similar
> prices. Some of these had BMS fitted and some just had cells wired to the
> terminals. Often the descriptions didn't mention whether they had a BMS
> or not.
>
> What I want to know is whether this undocumented mess is still the case
> or if you can now read published descriptions and know, with a fair
> degree of confidence, whether there is or is not a BMS and current
> limiter inside without having to chop the battery open to find out.
>
> If the adverts now give reliable information about this, then I'll
> investigate further: if not, I'll stick to SLAs for a while yet.
>
>

So has anybody gotten specs out of K2? They don't publish them openly,
but instead require that you register and request them. I did that and
they never replied. Maybe they blacklist anybody who can actually read
spec sheets.

[krasw]

Latest info is that due to this battery fire glider manufacturer (Binder) no longer approves or installs lifepo batteries on their gliders. Not sure if AD is in the works.

[kinsell]

On 06/17/2018 01:18 PM, krasw wrote:
> Latest info is that due to this battery fire glider manufacturer (Binder) no longer approves or installs lifepo batteries on their gliders. Not sure if AD is in the works.
>

Thanks for the update. I understand this was an EB-28 in Finland.

[JS[_5_]]

On Sunday, June 17, 2018 at 12:18:53 PM UTC-7, krasw wrote:
> Latest info is that due to this battery fire glider manufacturer (Binder) no longer approves or installs lifepo batteries on their gliders. Not sure if AD is in the works.

Any chance of learning what make and model of battery was in the EB28, so others flying with those particular batteries can be aware?
Jim
It's 7 years for me, Jon.

[jfitch]

On Sunday, June 17, 2018 at 12:18:53 PM UTC-7, krasw wrote:
> Latest info is that due to this battery fire glider manufacturer (Binder) no longer approves or installs lifepo batteries on their gliders. Not sure if AD is in the works.

Any details at all about the incident would be interesting to everyone......

There is nothing about it on the Binder website.

[krasw]

On Monday, 18 June 2018 03:37:20 UTC+3, JS wrote:
> On Sunday, June 17, 2018 at 12:18:53 PM UTC-7, krasw wrote:
> > Latest info is that due to this battery fire glider manufacturer (Binder) no longer approves or installs lifepo batteries on their gliders. Not sure if AD is in the works.
>
> Any chance of learning what make and model of battery was in the EB28, so others flying with those particular batteries can be aware?
> Jim
> It's 7 years for me, Jon.

I don't have that info, but it is probable that battery cells were ok and fire was caused by BMS circuit board. I have opened Aeroakku.com lifepo (sort of respected german seller that markets their products for aviation use). It contained chinese BMS circuit made of cheapest parts. Reason I opened it was that BMS electronics failed totally after 1,5 years use. It is very difficult to know what you get when purchasing lifepo batteries.

[[email protected]]

.....which begs the question - which manufacturers of LiFePo batteries can be relied on to be using high quality electronic components in the BMS?

[kinsell]

On 06/17/2018 06:37 PM, JS wrote:
> On Sunday, June 17, 2018 at 12:18:53 PM UTC-7, krasw wrote:
>> Latest info is that due to this battery fire glider manufacturer (Binder) no longer approves or installs lifepo batteries on their gliders. Not sure if AD is in the works.
>
> Any chance of learning what make and model of battery was in the EB28, so others flying with those particular batteries can be aware?
> Jim
> It's 7 years for me, Jon.
>

As much as you would dearly love to believe it's an issue with one
particular make and model, that's trying trying to extrapolate from one
(fuzzy) data point. Always a risky proposition.

[JS[_5_]]

On Monday, June 18, 2018 at 5:04:57 AM UTC-7, kinsell wrote:
> On 06/17/2018 06:37 PM, JS wrote:
> > On Sunday, June 17, 2018 at 12:18:53 PM UTC-7, krasw wrote:
> >> Latest info is that due to this battery fire glider manufacturer (Binder) no longer approves or installs lifepo batteries on their gliders. Not sure if AD is in the works.
> >
> > Any chance of learning what make and model of battery was in the EB28, so others flying with those particular batteries can be aware?
> > Jim
> > It's 7 years for me, Jon.
> >
>
> As much as you would dearly love to believe it's an issue with one
> particular make and model, that's trying trying to extrapolate from one
> (fuzzy) data point. Always a risky proposition.

Thanks for the link to Aeroaccu.com. Previously only aware of batteries from Accu-24.de in Europe. First saw those in the factory at Kirchheim.

Putting avgas, mogas or even Jet A in a composite aircraft with questionable plumbing is a risky proposition, yet that is considered normal. Some installations have uninsulated non-metallic tubing for fuel.
No glider manufacturer to my knowledge offers a fire extinguisher as an option.
Jim