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K2 battery endurance



 
 
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  #21  
Old May 26th 20, 04:47 AM posted to rec.aviation.soaring
Eric Greenwell[_4_]
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Posts: 1,476
Default K2 battery endurance

2G wrote on 5/25/2020 2:20 PM:
On Wednesday, May 13, 2020 at 8:00:09 PM UTC-7, kinsell wrote:

....

The BMS in all LFPs may not have the same functionality regarding balancing but at the very least they should start/stop accepting charge appropriately.


It matters not what you think should happen, the truth is not all LFP
batteries have a BMS, and of those that do, not all of them protect from
over and under voltage.


Which LFP batteries don't have a BMS?

Tom


The "powersports" (ie, for engine starting) LFP don't always have a BMS. A
motorglider pilot might be tempted to use one for the engine, for example.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1
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  #22  
Old May 30th 20, 03:50 PM posted to rec.aviation.soaring
SF
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Posts: 213
Default K2 battery endurance

One of my early K2's experienced a cell failure which dropped that battery's voltage output and lowered it's capacity. I run two batteries in parallel and had an experience like yours. Individual testing of each found the bad battery. Replacement is the only fix for this.

Battery testing can be done pretty easily and low tech. Using a voltmeter and 12V side marker lights from your local tractor supply. , 2-4 of the side marker lights should approximate your gliders normal electrical load. Plug them into the battery then check and record the voltage every half hour until it drops to 11.5V.

You can measure amperage with most multi-meters, just be careful to switch the leads back to voltage measurement. The cheap meters are not fused. Had a guy blow one up checking 480V with an un-fused meter set to measure current. It can cause serious injury, so exercise caution. The batteries we use in sailplanes can deliver enough energy to melt things if shorted out, so respect that potential when dealing with them. We had to evacuate a 300,000 SQFT manufacturing facility once because a technician shorted out a single lithium Ion battery cell in his test stand, The smoke from off-gassing was impressive.

SF
  #23  
Old May 30th 20, 10:46 PM posted to rec.aviation.soaring
kinsell
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Posts: 373
Default K2 battery endurance

Testing is always good, but John has a very reasonable suspicion the
problem was due to cold soaking the batteries. LFP's really don't like
the cold, and can even be damaged if charged below freezing. Maybe he
had a temporary loss of capacity that wouldn't show up under room temp
testing.




On 5/30/20 8:50 AM, SF wrote:
One of my early K2's experienced a cell failure which dropped that battery's voltage output and lowered it's capacity. I run two batteries in parallel and had an experience like yours. Individual testing of each found the bad battery. Replacement is the only fix for this.

Battery testing can be done pretty easily and low tech. Using a voltmeter and 12V side marker lights from your local tractor supply. , 2-4 of the side marker lights should approximate your gliders normal electrical load. Plug them into the battery then check and record the voltage every half hour until it drops to 11.5V.

You can measure amperage with most multi-meters, just be careful to switch the leads back to voltage measurement. The cheap meters are not fused. Had a guy blow one up checking 480V with an un-fused meter set to measure current. It can cause serious injury, so exercise caution. The batteries we use in sailplanes can deliver enough energy to melt things if shorted out, so respect that potential when dealing with them. We had to evacuate a 300,000 SQFT manufacturing facility once because a technician shorted out a single lithium Ion battery cell in his test stand, The smoke from off-gassing was impressive.

SF


  #24  
Old May 31st 20, 03:15 PM posted to rec.aviation.soaring
[email protected]
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Posts: 427
Default K2 battery endurance

On Saturday, May 30, 2020 at 5:47:01 PM UTC-4, kinsell wrote:
Testing is always good, but John has a very reasonable suspicion the
problem was due to cold soaking the batteries. LFP's really don't like
the cold, and can even be damaged if charged below freezing. Maybe he
had a temporary loss of capacity that wouldn't show up under room temp
testing.


LFPs don't like to be charged while cold (below the freezing point of water is the rule of thumb, even though they are not made of water). But they discharge just fine while (reasonably) cold. Their capacity while cold doesn't suffer anything like the way SLAs capacity does.
  #25  
Old May 31st 20, 04:03 PM posted to rec.aviation.soaring
[email protected]
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Posts: 79
Default K2 battery endurance

On Sunday, May 31, 2020 at 4:15:11 PM UTC+2, wrote:
On Saturday, May 30, 2020 at 5:47:01 PM UTC-4, kinsell wrote:
Testing is always good, but John has a very reasonable suspicion the
problem was due to cold soaking the batteries. LFP's really don't like
the cold, and can even be damaged if charged below freezing. Maybe he
had a temporary loss of capacity that wouldn't show up under room temp
testing.


LFPs don't like to be charged while cold (below the freezing point of water is the rule of thumb, even though they are not made of water). But they discharge just fine while (reasonably) cold. Their capacity while cold doesn't suffer anything like the way SLAs capacity does.


FYI the capacity does still suffer somewhat, -20% at -10c, http://liionbms.com/pdf/kokam/SLPB10...0Ah%20Nano.pdf
  #27  
Old June 2nd 20, 05:46 AM posted to rec.aviation.soaring
kinsell
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Posts: 373
Default K2 battery endurance

On 5/25/20 9:47 PM, Eric Greenwell wrote:
2G wrote on 5/25/2020 2:20 PM:
On Wednesday, May 13, 2020 at 8:00:09 PM UTC-7, kinsell wrote:

...

The BMS in all LFPs may not have the same functionality regarding
balancing but at the very least they should start/stop accepting
charge appropriately.


It matters not what you think should happen, the truth is not all LFP
batteries have a BMS, and of those that do, not all of them protect from
over and under voltage.


Which LFP batteries don't have a BMS?

Tom


The "powersports" (ie, for engine starting) LFP don't always have a BMS.
A motorglider pilot might be tempted to use one for the engine, for
example.


StarkPower had a series of batteries aimed at motorcycles that they were
quite open about not having a BMS. Unfortunately they're in Chapter 7
now and the website is gone.

More commonly, some batteries with BMS don't have over and under voltage
protection. Richard Pfiffner one time was testing batteries, and his
vendor shipped 24 volt chargers accidentally for 12 volt batteries. All
the white stuff leaked out of the battery. Some electrical genius on
R.A.S. (don't remember which one) declared that they really had
overvoltage protection, but 24 volts just wasn't enough to trigger it.

One of our fellow Schleicher motorglider pilots had an LFP, left the
transponder on, and ruined the battery. A 15-20 AH battery intended as
a starter battery can easily find it's way into other applications. You
may have read about the ASG 32 mi that got fried when the solar
controller malfunctioned, drained the battery, and got quite hot when
charged from another charger. Did it have a BMS? Doesn't really matter.

Dave


  #28  
Old June 2nd 20, 03:40 PM posted to rec.aviation.soaring
2G
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Posts: 1,041
Default K2 battery endurance

On Monday, June 1, 2020 at 9:46:09 PM UTC-7, kinsell wrote:
On 5/25/20 9:47 PM, Eric Greenwell wrote:
2G wrote on 5/25/2020 2:20 PM:
On Wednesday, May 13, 2020 at 8:00:09 PM UTC-7, kinsell wrote:

...

The BMS in all LFPs may not have the same functionality regarding
balancing but at the very least they should start/stop accepting
charge appropriately.


It matters not what you think should happen, the truth is not all LFP
batteries have a BMS, and of those that do, not all of them protect from
over and under voltage.

Which LFP batteries don't have a BMS?

Tom


The "powersports" (ie, for engine starting) LFP don't always have a BMS.
A motorglider pilot might be tempted to use one for the engine, for
example.


StarkPower had a series of batteries aimed at motorcycles that they were
quite open about not having a BMS. Unfortunately they're in Chapter 7
now and the website is gone.

More commonly, some batteries with BMS don't have over and under voltage
protection. Richard Pfiffner one time was testing batteries, and his
vendor shipped 24 volt chargers accidentally for 12 volt batteries. All
the white stuff leaked out of the battery. Some electrical genius on
R.A.S. (don't remember which one) declared that they really had
overvoltage protection, but 24 volts just wasn't enough to trigger it.

One of our fellow Schleicher motorglider pilots had an LFP, left the
transponder on, and ruined the battery. A 15-20 AH battery intended as
a starter battery can easily find it's way into other applications. You
may have read about the ASG 32 mi that got fried when the solar
controller malfunctioned, drained the battery, and got quite hot when
charged from another charger. Did it have a BMS? Doesn't really matter.

Dave


I think it matters: what kind of battery was it?

Tom
  #29  
Old June 2nd 20, 05:26 PM posted to rec.aviation.soaring
Richard Pfiffner[_2_]
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Posts: 239
Default K2 battery endurance

On Monday, June 1, 2020 at 9:46:09 PM UTC-7, kinsell wrote:
On 5/25/20 9:47 PM, Eric Greenwell wrote:
2G wrote on 5/25/2020 2:20 PM:
On Wednesday, May 13, 2020 at 8:00:09 PM UTC-7, kinsell wrote:

...

The BMS in all LFPs may not have the same functionality regarding
balancing but at the very least they should start/stop accepting
charge appropriately.


It matters not what you think should happen, the truth is not all LFP
batteries have a BMS, and of those that do, not all of them protect from
over and under voltage.

Which LFP batteries don't have a BMS?

Tom


The "powersports" (ie, for engine starting) LFP don't always have a BMS.
A motorglider pilot might be tempted to use one for the engine, for
example.


StarkPower had a series of batteries aimed at motorcycles that they were
quite open about not having a BMS. Unfortunately they're in Chapter 7
now and the website is gone.

More commonly, some batteries with BMS don't have over and under voltage
protection. Richard Pfiffner one time was testing batteries, and his
vendor shipped 24 volt chargers accidentally for 12 volt batteries. All
the white stuff leaked out of the battery. Some electrical genius on
R.A.S. (don't remember which one) declared that they really had
overvoltage protection, but 24 volts just wasn't enough to trigger it.

One of our fellow Schleicher motorglider pilots had an LFP, left the
transponder on, and ruined the battery. A 15-20 AH battery intended as
a starter battery can easily find it's way into other applications. You
may have read about the ASG 32 mi that got fried when the solar
controller malfunctioned, drained the battery, and got quite hot when
charged from another charger. Did it have a BMS? Doesn't really matter.

Dave


The problem batteries were Bioenno Batteries.

Richard
  #30  
Old June 2nd 20, 06:09 PM posted to rec.aviation.soaring
Eric Greenwell[_4_]
external usenet poster
 
Posts: 1,476
Default K2 battery endurance

Richard Pfiffner wrote on 6/2/2020 9:26 AM:
....


StarkPower had a series of batteries aimed at motorcycles that they were
quite open about not having a BMS. Unfortunately they're in Chapter 7
now and the website is gone.

More commonly, some batteries with BMS don't have over and under voltage
protection. Richard Pfiffner one time was testing batteries, and his
vendor shipped 24 volt chargers accidentally for 12 volt batteries. All
the white stuff leaked out of the battery. Some electrical genius on
R.A.S. (don't remember which one) declared that they really had
overvoltage protection, but 24 volts just wasn't enough to trigger it.

One of our fellow Schleicher motorglider pilots had an LFP, left the
transponder on, and ruined the battery. A 15-20 AH battery intended as
a starter battery can easily find it's way into other applications. You
may have read about the ASG 32 mi that got fried when the solar
controller malfunctioned, drained the battery, and got quite hot when
charged from another charger. Did it have a BMS? Doesn't really matter.

Dave


The problem batteries were Bioenno Batteries.


Were they Bioennos with a BMS that protects against overvoltage? For example, I
use the BLF-1220AS, which ....

"Includes built-in PCM (protection circuit module) which provides internal cell
balancing and management, protection from overcurrent, undervoltage
(overdischarge), overvoltage and short circuiting, and has integrated charging
circuitry "

I haven't tried applying 24 volts to it, but I'd expect it to protect against 24
VDC being applied to it. I've just emailed Bioenno this question, but have not
heard back.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1
 




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