Battery puffed in storage???

[j4jenk]

It's finally spring and my travel schedule is slowing down again, so I'm thinking I should put away the MSR and the SR120 and do a good preflight on my B450. Much to my surprise when I opened my lipo case, one of my Turnigy packs looks like it's pregnant.

I know things like batteries fail, and I'd like to chalk it up to bad luck, but I want to make sure I'm not missing something. I bought three of these from HK late last summer and put about 30 flights on each of them, charging them on the stock charger that came with the B450. I would make sure to land a little early on the last flight to keep them close to a "storage charge". In December I finally got around to upgrading my charger and put them at a proper storage charge until mid February when the we got a few days of surprisingly nice weather. I charged all 3 on my Thunder AC680, flew them each once, put them back on the AC680 for another storage charge, and then stored them back in my lipo case. Everything looked normal, and all cells were ~3.8V.

As you can see, when I pulled them out today the top cell on one is really puffed, but all cells still read ~3.8V, No other cells on that battery, or the other two batteries are even the slightest bit spongy.

What should I do with it?

I've heard of batteries puffing during use or charging, but is it common for them to puff in storage?

Any advice would be greatly appreciated.

Thanks,

[Khaag]

I hate unexpected fires in my house / heli. If it were me I'd pitch the pack.

[dannylightning]

soak them in a bucket of salt watter for a few days. that way they wont blow up on you or set the house on fire. dont use those things.

[dmcn2010@hotmail.com]

They do puff or swell but, I would dispose of it. The battery might read the correct voltage but under a load or nearing the end of a flight. No telling what the bad or weak cell will do. Battery cell imbalance while in flight is never a good thing and just not worth it.

[j4jenk]

I'm definitely tossing the one that's puffed. Salt water soak sounds like a good way to do it.

I assume that the others are still ok since they show no signs of puffing and still test fine.

Any ideas of what would cause such a failure?

[dannylightning]

are you putting them on storage charge before you store them

leaving them fully charged for long periods of time can screw up your packs. some packs are just lousy to start out with. you should never leave your packs charged longer than needed
the should be around 3.80V per cell at storage charge.

it's hard to say what caused it, the B 400 charger is junk. it does not balance your cells well. it can over charge some cells and not charge some enough. and stuff like that. after having issues with mine i went out and got a nice charger.

[spikestabber]

Only time I ever had packs puff in storage is when I left them at a full charge for months.... my own fault I know. Never again.

[AcidDrink]

Personally I'd dispose all of them immediately, puffed one at least.

Hard to say what caused this, it could be temperature, quite likely it could puff right after charging, a short.

[j4jenk]

Originally Posted by dannylightning

are you putting them on storage charge before you store them

leaving them fully charged for long periods of time can screw up your packs. some packs are just lousy to start out with. you should never leave your packs charged longer than needed
the should be around 3.80V per cell at storage charge.

it's hard to say what caused it, the B 400 charger is junk. it does not balance your cells well. it can over charge some cells and not charge some enough. and stuff like that. after having issues with mine i went out and got a nice charger.

This is the part that I have questions about. I'm sure that the crap stock charger didn't help at all, and I'm not sure exactly what was going on in each cell with my "land early" method of hitting a storage charge, so I would say I probably abused them a bit. The confusing part for me is that after I upgraded the charger, they were always properly charged, balanced, and put at a 3.8V per cell storage charge.

Could the puffing be from latent damage that was done before I upgraded chargers? Do failures like this always have a user caused origin?

[spikestabber]

Or it might not even be your fault. Crappy cell....
In your picture it looks like a single cell puffed.

[FuntanaS]

According to Dave from Progressive RC you are not suppose to put your batteries in salt water to kill them. He says to just drain them to as close to 0 volts as you can.

He was on the latest episode of RC Heli Nation.

[dannylightning]

Thunder power says to dispose of your packs soak them. Dave says something different that is cool too but I would not hook that puffed pack up to something or it could possivly catch fire

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[sansone]

Originally Posted by spikestabber

Only time I ever had packs puff in storage is when I left them at a full charge for months.... my own fault I know. Never again.

done that once also

[j4jenk]

Definitely not hooking the puffed pack up to anything.

I thought about taking it to the range, but I think there is a rule against explosive targets

[dannylightning]

They just shoot out a flame for a few seconds and smoke allot, at least that is what I have seen when some one shot one with a .22 not sure if a larger bullet would make it blow up or not

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[desertstalker]

Originally Posted by dannylightning

They just shoot out a flame for a few seconds and smoke allot, at least that is what I have seen when some one shot one with a .22 not sure if a larger bullet would make it blow up or not

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LiPos will not explode, they may burn (quite vigorously in some cases), but the typical result (even if you shoot them or use a nail gun) is quite a bit of heat, and a lot of smoke (stay out of this its not very good for you). You wouldn't be the first to shoot one... only way a bullet will make them "explode" is from the force of impact.

Best way to dispose of them is to discharge very slowly (say over 2+ days) to 0V outside on a non-flammable surface (like dirt ) just in case a damaged cell ruptures (they may swell but at such a slow rate they shouldn't rupture), then connect the leads together and throw away. Placing them in salt water can corrode away the tabs from the cells before the pack is discharged.

[fozz]

I use 12V tail light bulbs to drain 3S batteries for disposal. I do this in a fire safe location of course. Then into the salt bath to drain any remaining voltage. I check each cell with a volt meter to make sure they are dead. When there is no voltage left, lipos are inert.

[j4jenk]

I discharged the battery on a 12V tail light overnight, and couldn't detect any voltage when I pulled it off the next morning. This being my first lipo failure, I wanted to do some diagnostics to see I could find any direct cause for the failure.

After removing the wrapping I found what you see pictured on the cell that was puffed. This was under the flap that you see lifted up, and there was no "trauma" to that, or any, area of the battery. Does anyone have any idea what would cause this?

I'm not sure if this is the cause of the failure, or a result of the failure.

Anyone have any suggestions for additional diagnostics before I soak it in saltwater and dispose of it?

[Blade120]

Looks like lipo linchen simplex usually happens as a result of poor sanitary conditions at the factory and excessive use of antibiotics

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[Dr. M]

I'd call that a manufacturing defect. Sometimes it just happens. Looks like it wasn't your fault at all.