Don't forget about those batteries!

[OV10]

How can the voltage rise in batteries while in storage? Mine went from 11.7v to 12.2v while in storage for 3 weeks. Never noticed this happening before. Doc

Doc, was that across all your batts? Did you use the same measuring device this time as the prior?
Did you subject them to a change from a low temp range to a more ambient(room) temp which induces the chemistry to "wake up" and become more active.
11.7 equates to a cell average of 3.9 which indicates they really weren't at storage levels.
:pop

[skippykix]

How can the voltage rise in batteries while in storage? Mine went from 11.7v to 12.2v while in storage for 3 weeks. Never noticed this happening before. Doc

Wow Doc, I have never heard of that happening.

[doctormike]

How can the voltage rise in batteries while in storage? Mine went from 11.7v to 12.2v while in storage for 3 weeks. Never noticed this happening before. Doc

[WintrSol]

I check mine with a cell tester, to see if any have cells that are starting to drift below the storage level; if I find any, I charge them for a while (to about 3.9V on the lowest cell), then use a balancing discharger to reset them. I've had very few exhibit discharge in storage mode, but I think it's worth the trouble.

[skippykix]

Do you keep them in "storage" voltage? IE, ~3.8v/cell. I have batteries that are coming on 4 years old with a couple hundred cycles on them. I may consider replacing them during next summer but if they still work, I'll just keep going with them. Through the winter, when I fly only skidders on the snow/ice, many of my batteries (and I have over 50 of them , 2s to 6s) just sit there untouched for 6 months or more. I don't cycle them at all during the storage months and when I do take them out and charge them, they work just as good as when I last flew them.
If you store them at storage charge, I'm not sure you gain anything if you cycle them or not. Batteries can be kept in storage charge for years at room temp or cooler. If you leave them unused at full charge or well below 3.5v/cell for months on end, that's another story. However, having said that, battery owners should do what makes them feel like they did the right thing.

I found that that cycling them every other month during the winter keeps the cells better balanced. I also like to know if I have a battery with a issue before flying season starts.

[doctormike]

Thanks for the reminder. I get lazy and forgetful about my batteries during the winter months. I'm going to test them today. Doc

[fhhuber]

I've always bought lower end LiPos so better might do a little better.

I have found that with LVC set so the packs come out of the plane close to 3.7v/cell, just leave them there for storage.

Some batteries might not get used for a few months while others are used several recharges a week. it depends on which stuff i am flying.
TIME seems more important than charge cycles.

I average 3.5 years and 350 charge cycles under the high load of an EDF (on 20 C packs) with 3 min average flight times using 75% of rated capacity.
THEN the packs start not being able to handle the full throttle current of the EDF.
I can still get another year to year and a half of flying planes that get 7 to 10 min average flight times. Maybe another 100 charge cycles.
After that the packs are losing both current delivery capability and capacity badly enough I tend to drive a nail through them and burn them for disposal.

Never leave a full charge LiPo in a hot car, especially here in Texas. When the car interior goes above 150F a full LiPo WILL puff and might burn. A discharged LiPo will survive a higher temperature than a full one.

LiPos are ALWAYS damaged by temperatures above 150F whether it be from being in a hot car or heating due to high current demand with poor cooling.

[OV10]

On the money XV ;)..........these LiPo's don't develop a memory voltage like old tech Nicads did that needed to be cycled.

[xviper]

Do you keep them in "storage" voltage? IE, ~3.8v/cell. I have batteries that are coming on 4 years old with a couple hundred cycles on them. I may consider replacing them during next summer but if they still work, I'll just keep going with them. Through the winter, when I fly only skidders on the snow/ice, many of my batteries (and I have over 50 of them , 2s to 6s) just sit there untouched for 6 months or more. I don't cycle them at all during the storage months and when I do take them out and charge them, they work just as good as when I last flew them.
If you store them at storage charge, I'm not sure you gain anything if you cycle them or not. Batteries can be kept in storage charge for years at room temp or cooler. If you leave them unused at full charge or well below 3.5v/cell for months on end, that's another story. However, having said that, battery owners should do what makes them feel like they did the right thing.

[digger38]

Thank You for the reminder. Seams I forget that every year unless I make up a schedule and put it on a calendar.

[skippykix]

Hey guys, I just want to throw out "Don't forget about those batteries" while we are shivering in the cold! At least throw a cycle on them just to wake them up. They will thank you come this spring.