Data Complete Guide to Lithium Polymer Batteries and LiPo Failure Reports

[jmralves]

Originally Posted by aeajr

You can charge the packs on a regular charger,

Maybe you shouldn't use the word regular to define a lipoly charger.

The Charger must be ESPECIFIC or have a especific program to charge lipoly packs.

Just check the lipo manufacturers web pages to see the characterisitics that a lipoly charger MUST have.

Jorge

[zedfor]

Jim,
Many thanks for a most comprehrnsive guide to Li Poy batteries. One question though if I may; you recommend charging at not more than 1C, is there anything to be gained by charging at lower rates?

[hall woo]

better operating time like your slow charged TX

when did u last fast charged your radio transmitter

[fadedtears]

Now I am curious. I bought a honeybee heli e005 that came with a 3 lipo cell. I have just ordered a 3 cell wall charger

wall charger I ordered Lithium Charger for 11.1 V (3-Cell) Battery Simple Convenient Wall Unit Input: 100V / 220V, 50-60 hz, Output: 12.6V, 1amp Only use this charger on our 730mAh or 800mAh packs. Do not use this charger on our 340mAh or 380mAh packs at wildrc.com

and an extra 3 cell 1000mAh. at a different site.

My question is .. should I goto the local hobby store and get another battery type for my heli and sell these set or is it safe enough for me to use them.

My concern is that if I go off to work and the battery goes up in flame when I am not here to put it out. ((edit) I need to also add.. I am not planning to charge the battery when I am not at home.)

Any suggestion would be appreciated.

Thanx

OH yeah this is my first rc heli .. also how do a firesafe looks like.. anyone has a picture.. Can I get this at a homedepot store or I have to buy it at a hobby store?

[mrm1]

I think you will be safe with Lipos, but not real sure if you will be safe with the charger. Sent you a PM about that.

[aeajr]

Originally Posted by fadedtears

My question is .. should I goto the local hobby store and get another battery type for my heli and sell these set or is it safe enough for me to use them.

My concern is that if I go off to work and the battery goes up in flame when I am not here to put it out. ((edit) I need to also add.. I am not planning to charge the battery when I am not at home.)

Any suggestion would be appreciated.

1) The current generation of Lipoly batteries, with extremely rare exception, must be charged at 1C rate or less. Faster than that and you can have problems.

2) Never leave Lithium batteries charging unattended.

3) If you are going to leave them unattended when you are charging them, then do it outside, away from anything flamable and put the pack in a fire safe container such as a metal box. This way if it does burn, the burn will be contained, outside, away from anything flamable.

If these procedures are too incovnenient, then use NiMh packs.

[fadedtears]

Thanx mrm1 & aeajr...

[av8r]

I ran a 3S TP2100 PL down to a resting voltage after the flight of 9.79V. LVC did not occur (ESC set for 9V LVC) and it still had lots of power. The pack's temperature was 112 degrees measured with an infrared gauge. After it cooled, the voltage came back up to 10.09V. The TP205 balancer indicated that it was more than .03V out of balance. I checked each cell with a Fluke DMM and they were 3.342V, 3.390V & 3.360V, .048 out of balance. The TP205 wouldn't auto balance it, so I started the charge at .3A, then after a few minutes when the TP205 indicated that it was no longer unbalanced, bumped it up to 1A, then a little later up to 1C at 2.1A. It took 2269mAh of charge back in using an ICE charger. How could it take more charge than its rated capacity and is this a problem? Thanks.

[hall woo]

tp pl 3s 2100 mah underrated, got mine to discharge ~2240 mah

[NCC-1701]

Originally Posted by hall woo

tp pl 3s 2100 mah underrated, got mine to discharge ~2240 mah

At how many amps? The discharge rate has a big infuence on the effective capacity.

[toxdoc]

Originally Posted by Jim McPherson

mattg made an excellent suggestion. ..... Please dispose of damaged cells by placing them in salt water. Do not try to recreate DNA's testing.....,excerp.

-Jim

Jim..

Could you please elaborate on the proper disposal method for me. I actually have had an ElectriFly pack sitting in a metal container (very puffed 3 cell!) that I frankly didn't know what to do with....

thanks

Steve

[Larry3215]

Originally Posted by toxdoc

Jim..

Could you please elaborate on the proper disposal method for me. I actually have had an ElectriFly pack sitting in a metal container (very puffed 3 cell!) that I frankly didn't know what to do with....

thanks

Steve

Do NOT use a salt water bath to discharge lipos prior to disposal.

See this thread - especially the last 3 posts.

http://www.rcgroups.com/forums/showthread.php?t=507990

If it is a 3 cell pack:
1)get a 100 ohm 5 watt watt resistor and hook it across th eleads and leave it for a day or two.
2)or hook it up to your speed controller for several days
3)or use an Astro 109 to discharge it (do the Astro several times in a row)
4)or hook it up to a 12 volt light bulb untill it is dead - wait a good while AFTER the light goes out to check voltage.

Do any of the above untill the cells read less than 3 volts per cell. For a 3 cell pack that means a total of less than 9 volts. Measure the voltage several minutes AFTER you disconect the load.

I wish they would change the sticky to remove that salt water reference. The sellers of lipos ned to change thier recomendations as well.

Larry

[Osprey Engineer]

I have a polyquest 3 cell, 1200 mah, 20C pack that is swollen and I can't figure out why. I measured the voltage of the cells after flying.
4.00 V (cell 1 = 4 V)
7.99 V (cell 2 = 3.99 V)
12.98 V (cell 3 = 3.99 V)

The battery was swollen before I flew. Prior to flying I charged it and put it away for a few days. I pulled it out yesterday and saw that it was swollen. I don't think is was swollen after the charge. I decided to fly with it any way. It lost power in about 30 seconds.

I have read about the causes and have ruled out the following.

Didn't over charge or charge at greater than 1C. My Apache charger's highes setting is 3 cell 1200 mah

No crashes. Only about 15 cycles out of this battery. Neither motor nor battery is ever warm after a flight even with WOT.

My motor and prop only pull 9.5 A and the battery can deliver 24 A

Battery is stored in bubble wrap, in a hard case, in the trunk of my car. Tempatures have not been too hot yet so I don't think the trunk could have ever exceeded 100 deg F.

Any ideas or other possible causes I missed?
My next step is to charge it (in a bunker) and measure the cells.

So when is it the manufacturer's fault and not ours? Can I send back the battery as defective?

And one last question. If only one cell is bad, can the pack be disassembled so that I can use the 2 good cells?

Thanks

[hall woo]

never charge any swollen lipo packs, remove the bad cell before charging the two maybe good remaining cells, and then take the time to do a discharge capacity test using a wattmeter or af 109

[Larry3215]

Originally Posted by Osprey Engineer

I have a polyquest 3 cell, 1200 mah, 20C pack that is swollen and I can't figure out why. I measured the voltage of the cells after flying.
4.00 V (cell 1 = 4 V)
7.99 V (cell 2 = 3.99 V)
12.98 V (cell 3 = 3.99 V)

The battery was swollen before I flew. Prior to flying I charged it and put it away for a few days. I pulled it out yesterday and saw that it was swollen. I don't think is was swollen after the charge. I decided to fly with it any way. It lost power in about 30 seconds.

I have read about the causes and have ruled out the following.

Didn't over charge or charge at greater than 1C. My Apache charger's highes setting is 3 cell 1200 mah

No crashes. Only about 15 cycles out of this battery. Neither motor nor battery is ever warm after a flight even with WOT.

My motor and prop only pull 9.5 A and the battery can deliver 24 A

Battery is stored in bubble wrap, in a hard case, in the trunk of my car. Tempatures have not been too hot yet so I don't think the trunk could have ever exceeded 100 deg F.

Any ideas or other possible causes I missed?
My next step is to charge it (in a bunker) and measure the cells.

So when is it the manufacturer's fault and not ours? Can I send back the battery as defective?

And one last question. If only one cell is bad, can the pack be disassembled so that I can use the 2 good cells?

Thanks

Your math is in error. That pack is severly out of balance. 12.99 - 7.98 = 4.99 volts. Cell 3 is at 4.99 volts.

Thats is a very very dangerous condition.

Keep the pack in a fire safe place, treat it with extreem caution and slowly discharge it untill the voltage drops so that the hi cell is well under 4 volts.

Do NOT put it in salt water.

Trying to salvage the pack is risky at best. The puffed cell is toast.

Warrantee varries from sullpyer to supplyer.

Do NOT ship a puffed pack that is charged up. It could explode in transit and YOU could be liable for damages/death etc.

Good luck!

Larry