After a year of sitting...

[Plane Hazza]

My LiPos have sat in storage for about a year now, without a single charge or trickle charge. Will they be completely flat and ruined? Or will I be able to 'trickle' them back up to strength?

Thanks!

[rjg]

I would use a DVM (Digital Volt Meter) to check the current voltage of the pack, then if it is reasonable and check them for any signs of puffing or swelling. Then I would charge them at a really low rate 1/10C and then see if they hold their voltage after the charge is over.

If they do, then use them, but be kind of easy and then charge them again at the normal rate and go from there..

[Plane Hazza]

OK, I'm charging them up atm.

I must have left them more charged than I though, roughly 90% charged, so I dunno if that will have harmed them or not. They spent a year in a cold, damp shed under a ceramic 1" thick pot at 90% charge - oh dear.

When I plugged them into the charger/balancer (pro peak prodigy/Poly Pro LiPo Balancer Guard) the first pack registered at 11.5V. After 7mins of charging at 1A (just under 0.5C) it has put in 100mA and the voltage is at 12.5V.

Sound OK?

One of the smaller packs (I haven't charged yet) has slightly swollen. But the swelling is very soft, so I can't tell if its the cell or just the packaging. Its a smaller 1350mAh pack (3S1P, 20C Cont), so I'll charge that one up VERY slow to see how it goes.

[terrabit]

Storing lipos with a full charge for extended periods will tend to accelerate corrosion of electrodes which effectively decreases cycle life. Corrosion occurs regardless albeit at a slower rate. As a lipos deteriorate, they deliver less and less peak amperage (punch) for shorter periods of time (peak flight time) , and become increasingly difficult to maintain balance between cells until they are basically unuseable.

Be cautious! Watch for excessive heat! That can be a sign of unbalanced cells and lead to thermal runnaway or ... FIRE!!!!! Don't leave them in your heli or anywhere that they can start a fire. You really shouldn't do that anyway, even with healthy lipos. Use them CAREFULLY until they quit scratching your itch. Then get some new ones.

Peace out!
t-bit