Interesting behavior from PowerSonic battery

[Steve Leonard[_2_]]

I have two 6 volt and one 2 volt PowerSonic cells in series to make a 14 volt pack for one of my sailplanes. I had one of the batteries go bad, so I did a little checking to see which one. All showed appropriate charge voltage when not loaded, however, one battery went from 6.2 volts no load, to showing -3.8 or so volts when loaded by turning on a S-Nav and GPS-Nav. Now, I have seen an individual battery go to very nearly zero volts, but never negative voltage! Turn everything off, and it slowly recovers back to showing about 6.2 volts no load.

Anyone else ever seen a battery do that before? And please, no comments about 14 volt battery packs or old technology batteries. Age of battery unknown, as I do not remember when I built up the pack.

Just curious.

[Andy[_1_]]

I had one 12V SLA that showed full voltage unloaded but when selected in the glider caused all avionics to cycle on/off with a 1-2 sec period. Don't remember what the loaded volage was but I think it was close to zero. The unloaded voltage was, if anything, higher than normal.

Andy

[Jim[_31_]]

On Monday, May 6, 2013 3:31:41 PM UTC-4, Steve Leonard wrote:
> I have two 6 volt and one 2 volt PowerSonic cells in series to make a 14 volt pack for one of my sailplanes. I had one of the batteries go bad, so I did a little checking to see which one. All showed appropriate charge voltage when not loaded, however, one battery went from 6.2 volts no load, to showing -3.8 or so volts when loaded by turning on a S-Nav and GPS-Nav. Now, I have seen an individual battery go to very nearly zero volts, but never negative voltage! Turn everything off, and it slowly recovers back to showing about 6.2 volts no load.
>
>
>
> Anyone else ever seen a battery do that before? And please, no comments about 14 volt battery packs or old technology batteries. Age of battery unknown, as I do not remember when I built up the pack.
>
>
>
> Just curious.

Since you have all the batteries in series with the load the voltage drop across the bad battery it appears like the bad battery is being reverse-biased by the good ones. You would see the same kind of result if you replaced the bad battery with a resistor and measured the voltage across it. The bad battery obviously has what is called "High internal resistance".

-PC

[BobW]

On 5/6/2013 1:31 PM, Steve Leonard wrote:
> I have two 6 volt and one 2 volt PowerSonic cells in series to make a 14
> volt pack for one of my sailplanes. I had one of the batteries go bad, so
> I did a little checking to see which one. All showed appropriate charge
> voltage when not loaded, however, one battery went from 6.2 volts no load,
> to showing -3.8 or so volts when loaded by turning on a S-Nav and GPS-Nav.
> Now, I have seen an individual battery go to very nearly zero volts, but
> never negative voltage! Turn everything off, and it slowly recovers back
> to showing about 6.2 volts no load.
>
> Anyone else ever seen a battery do that before?

I've not seen that, but - digital VOM attached - I've seen a new/under full
replacement warranty standard 12V car battery intermittently become a 6V
battery, engine running & engine off, battery connected to the system. The
vehicle wouldn't run in "6V mode." It took some persuasion for the lady owner
of the vehicle to get the chain to honor their battery warranty, but her
vehicle hasn't suffered a "mystery engine stoppage" since flaky battery
replacement several years ago.

Bob W.

[Steve Leonard[_2_]]

On Monday, May 6, 2013 5:14:28 PM UTC-5, Jim wrote:
Since you have all the batteries in series with the load the voltage drop across the bad battery it appears like the bad battery is being reverse-biased by the good ones. You would see the same kind of result if you replaced the bad battery with a resistor and measured the voltage across it. The bad battery obviously has what is called "High internal resistance". -PC

Yep. And the guy at All Pack gave the battery the highly scientific "shake test". Apparently, the innerds dried up and came apart. Sounded like shaking a box of rocks. 5 years of service from the battery, and $23 to replace it in the pack. Will be good to be able to secure the battery in the intended box again rather than having a smaller one out on the shelf behind me.

[tstock]

On Monday, May 6, 2013 3:31:41 PM UTC-4, Steve Leonard wrote:
> I have two 6 volt and one 2 volt PowerSonic cells in series to make a 14 volt pack for one of my sailplanes. I had one of the batteries go bad, so I did a little checking to see which one. All showed appropriate charge voltage when not loaded, however, one battery went from 6.2 volts no load, to showing -3.8 or so volts when loaded by turning on a S-Nav and GPS-Nav. Now, I have seen an individual battery go to very nearly zero volts, but never negative voltage! Turn everything off, and it slowly recovers back to showing about 6.2 volts no load.
>

Flip the meter around and you can measure the voltage drop of that battery which is now just a big resistor :)

[2G]

On Monday, May 6, 2013 12:31:41 PM UTC-7, Steve Leonard wrote:
> I have two 6 volt and one 2 volt PowerSonic cells in series to make a 14 volt pack for one of my sailplanes. I had one of the batteries go bad, so I did a little checking to see which one. All showed appropriate charge voltage when not loaded, however, one battery went from 6.2 volts no load, to showing -3.8 or so volts when loaded by turning on a S-Nav and GPS-Nav. Now, I have seen an individual battery go to very nearly zero volts, but never negative voltage! Turn everything off, and it slowly recovers back to showing about 6.2 volts no load.
>
>
>
> Anyone else ever seen a battery do that before? And please, no comments about 14 volt battery packs or old technology batteries. Age of battery unknown, as I do not remember when I built up the pack.
>
>
>
> Just curious.

This is called "cell reversal" and does occassionally happen.

My question is why do you think that you need a 14V battery? All modern aviation electronics is designed to operate on a wide range of input voltage. This is accomplished by a circuit called a "dc-dc converter" that boosts the input voltage to a higher, regulated, internal voltage.

Tom

[Bob Kuykendall]

On May 21, 2:32 pm, 2G > wrote:

> ...My question is why do you think that you need a 14V
> battery? All modern aviation electronics is...

My suspicion is that Steve has a collection of vintage avionics that
is not even in the same zip code as "modern," and that said devices
start crapping out at around 11 volts. With the 14v pack, you have
three volts of margin between nominal and nordo; with the 12v pack you
have only one volt of margin.

Thanks, Bob K.

[Ralph Jones[_3_]]

On Tue, 21 May 2013 15:20:17 -0700 (PDT), Bob Kuykendall
> wrote:

>On May 21, 2:32 pm, 2G > wrote:
>
>> ...My question is why do you think that you need a 14V
>> battery? All modern aviation electronics is...
>
>My suspicion is that Steve has a collection of vintage avionics that
>is not even in the same zip code as "modern," and that said devices
>start crapping out at around 11 volts. With the 14v pack, you have
>three volts of margin between nominal and nordo; with the 12v pack you
>have only one volt of margin.
>
Quite so. Traditional avionics are designed to run on the 13.8V you
get from the voltage regulator in a "12 volt" system.

rj

[Steve Leonard[_2_]]

On Tuesday, May 21, 2013 4:32:29 PM UTC-5, 2G wrote:
This is called "cell reversal" and does occassionally happen. My question is why do you think that you need a 14V battery? All modern aviation electronics is designed to operate on a wide range of input voltage. This is accomplished by a circuit called a "dc-dc converter" that boosts the input voltage to a higher, regulated, internal voltage. Tom

Well, 2G, where do you draw the line on "Modern" avionics? MicroAir radio? Becker 3201 radio? Becker 4201 radio? Filser ATR500? I have seen all of the above "crap out" on a 12 volt battery when my Cambridge computer and nav keep on working.

Be happy with your 12 volt system, and don't be diss-ing on me for my 14 volt system, OK?

And, yes. I am aware of cell reversal. I just hadn't seen it "self recover" when the load is removed.

[Eric Greenwell[_4_]]

Steve Leonard wrote, On 5/23/2013 9:13 AM:
> On Tuesday, May 21, 2013 4:32:29 PM UTC-5, 2G wrote: This is called
> "cell reversal" and does occassionally happen. My question is why do
> you think that you need a 14V battery? All modern aviation
> electronics is designed to operate on a wide range of input voltage.
> This is accomplished by a circuit called a "dc-dc converter" that
> boosts the input voltage to a higher, regulated, internal voltage.
> Tom
>
> Well, 2G, where do you draw the line on "Modern" avionics? MicroAir
> radio? Becker 3201 radio? Becker 4201 radio? Filser ATR500? I
> have seen all of the above "crap out" on a 12 volt battery when my
> Cambridge computer and nav keep on working.
>
> Be happy with your 12 volt system, and don't be diss-ing on me for my
> 14 volt system, OK?

The Becker AR4201 is a "modern" radio, meeting the standard requirements
to transmit and receive at 10 volts. But, if a 12 volt battery has
dropped below 11 volts, it has so little energy left, it may not be able
to operate the 4201 in transmit mode; however, it should still receive
properly. If it won't receive with voltages between 10 and 11 volts, it
isn't operating properly, and I would send it in for repair.

The Cambridge computer and Nav can work on even lower voltages than the
10 volt specification for a transceiver, so they would work longer than
the radios.

The AR3201 is also a "modern" radio, and has the same voltage operating
specifications as the AR4201. Ditto for the ATR500. The Microair, at
least the earlier versions (don't know about the latest), is not a
"modern" radio, and has a much more limited voltage operating range than
the ATR500, AR3201, and AR4201.

Many thousands of pilots have (and still are) successfully operated
these very popular radios on 12 volts for over two decades. Since you've
had problems with all three radios that thousands of other pilots don't,
perhaps your installation was causing it; Possibly, your 12 volt battery
capacity was inadequate (battery too small or in poor condition), and
you simple ran out of charge. Adding a 14 volt battery to a marginal 12
volt system would increase the battery capacity, allowing you run longer.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)
- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm
http://tinyurl.com/yb3xywl

[Steve Leonard[_2_]]

On Thursday, May 23, 2013 1:00:50 PM UTC-5, Eric Greenwell wrote:

The Becker AR4201 is a "modern" radio, meeting the standard requirements to transmit and receive at 10 volts. But, if a 12 volt battery has dropped below 11 volts, it has so little energy left, it may not be able to operate the 4201 in transmit mode; however, it should still receive properly. If it won't receive with voltages between 10 and 11 volts, it isn't operating properly, and I would send it in for repair. The Cambridge computer and Nav can work on even lower voltages than the 10 volt specification for a transceiver, so they would work longer than the radios. The AR3201 is also a "modern" radio, and has the same voltage operating specifications as the AR4201. Ditto for the ATR500. The Microair, at least the earlier versions (don't know about the latest), is not a "modern" radio, and has a much more limited voltage operating range than the ATR500, AR3201, and AR4201. Many thousands of pilots have (and still are) successfully operated these very popular radios on 12 volts for over two decades. Since you've had problems with all three radios that thousands of other pilots don't, perhaps your installation was causing it; Possibly, your 12 volt battery capacity was inadequate (battery too small or in poor condition), and you simple ran out of charge. Adding a 14 volt battery to a marginal 12 volt system would increase the battery capacity, allowing you run longer. -- Eric Greenwell - Washington State, USA

I also have Terra TX-720s (I know. ANCIENT. But, they work). I also know that most people running 12 volt batteries carry a second and even a third 12 volt battery as "backups". Some have even more than that. I have a single 14 volt battery in most everything I fly. And my one 14 volt battery is lighter than your two or three or four 12 volt batteries. I would much rather have one system that is reliable and will work all the time than several that will work, but must be changed during a long flight.

All of the above noted radio crap-outs have been lack of transimission from one of those radios hooked to a 12 volt battery some time into the flight. They all still receive just fine. Not all have been me personally. So, my crappy wiring isn't the fault in all of these instances. :-)

Feel free to continue enjoying the added security you feel with multiple 12 volt batteries and the associated wiring, switches, fuses, etc. Just like so many people need to have backup loggers becasue what they have sometimes fails. Me? I have a Cambridge Model 20. Has never failed. Other things are newer, and some may be better, but none that I am aware of have had fewer bugs or lockups in flight.

My favorite quote about a backup system, and maybe it was just how I chose to read it, was from A.J. Smith. Talking about the AS-W12 and the addition of a second drag chute, in case there was an issue with the primary. He said "That way, you get TWO failures per flight."

Now, lets all just get our batteries charged and get ready for a fun weekend of flying, OK?

[Eric Greenwell[_4_]]

Steve Leonard wrote, On 5/23/2013 11:28 AM:
> My favorite quote about a backup system, and maybe it was just how I
> chose to read it, was from A.J. Smith. Talking about the AS-W12 and
> the addition of a second drag chute, in case there was an issue with
> the primary. He said "That way, you get TWO failures per flight."

AJ isn't around to ask about it, but you why don't ask a skydiver about
why they bother with a reserve parachute ;^)

My point is, there are several reasons to have more than one battery,
and none of them are related to how much voltage a "modern" radio needs.

For your setup, with a TX 720, 14 volts may be a good choice, as it's
voltage input is specified at 13.75 volts. It was not designed to the
same requirements that have been in effect for certified radios for over
20 years, which require operation over a wide voltage range.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)
- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm
http://tinyurl.com/yb3xywl

[Dan Marotta]

Sky divers 'bother' with a reserve parachute because the law requires it.
BASE jumpers, outlaws by nature, don't bother because there's no time for a
reserve.


"Eric Greenwell" > wrote in message
...
> Steve Leonard wrote, On 5/23/2013 11:28 AM:
>> My favorite quote about a backup system, and maybe it was just how I
>> chose to read it, was from A.J. Smith. Talking about the AS-W12 and
>> the addition of a second drag chute, in case there was an issue with
>> the primary. He said "That way, you get TWO failures per flight."
>
> AJ isn't around to ask about it, but you why don't ask a skydiver about
> why they bother with a reserve parachute ;^)
>
> My point is, there are several reasons to have more than one battery, and
> none of them are related to how much voltage a "modern" radio needs.
>
> For your setup, with a TX 720, 14 volts may be a good choice, as it's
> voltage input is specified at 13.75 volts. It was not designed to the same
> requirements that have been in effect for certified radios for over 20
> years, which require operation over a wide voltage range.
>
> --
> Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
> email me)
> - "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm
> http://tinyurl.com/yb3xywl

[Eric Greenwell[_4_]]

Dan Marotta wrote, On 5/24/2013 8:37 AM:
> Sky divers 'bother' with a reserve parachute because the law requires it.

Not the ones I've talked to.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)
- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm
http://tinyurl.com/yb3xywl