Lipo storage?
 

How can you keep a lipo fully charged before you need to discharge it for storage?

Not sure I understand your ques...but you don't keep lipo fully charged, at least I don't - they last longer and have less probs that way.

After running, I used to recharge, but now all I do is check voltage. If between 3.7 - 3.85v/cell, I leave them until just before running again and then they are fully charged right before using them.

If the voltage is lower than I like to see, I put them on charger and storage charge them.

I read somewhere that you need to discharge them if not in use, basically is ther a issue if fully charged and not used for a while.

idk where the article is i cant find it...but i read to store lipos at 40%, and to store in pretty cool temp. I know the charger i have, has a mode on there for me to set for me to charge it to a storage point then itll cut off.

It's never a good idea to leave them in a fully charged state for a long period of time. I've had first hand accounts of friends lipos getting puffy just sitting on a shelf fully charged. While there may be other factors involved this practice seemed to be common between them.

I myself have always put them in storage mode after a race. They'll stay that way and get charged up the night before the next race. So far so good!

what is "storage mode" ?

The Rev-Tech batteries I have came with a recommendation paper, they say not to leave a (their) battery fully charged state for more than 2 hours as this could cause cells to swell.

Storage mode is just another function found on just about any lipo charger that can do the standard charging, balancing and discharging. The storage option would be found in the same place. Basically if you choose this the charger will automatically charge OR discharge your battery to a preset (user changeable) value per cell. The default is usually around 3.4v per cell. Once completed this should leave your pack with about a 60% charge and can safely be left this way for extended periods.

3.85v / cell is roughly 50% and the usual setting for most storage modes

Anywhere between 3.7v and 4.0v per cell is fine

A lipo cell is basically empty at a resting voltage of 3.5v, no reason to ever go below it

Cheers

Like everyone said, 3.85-3.87 v per cell is always what Ive stored them at if it was gonna sit longer than a few days. Ive read several post where people store them fully charged and they said theres never any problems. But why chance it?

Any time a lipo cell sits fully charged it will start to degrade

The effect is cumulative and the cell resistance will rise over time

Most dont hold onto their packs long enough to worry about it (or they die early)

3.85v is an arbitrary value based on a table similar to this

Resting voltage vs capacity

4.2v - 100%
4.13v - 90%
4.06v - 80%
3.99v - 70%
3.92v - 60%
3.85v - 50%
3.78v - 40%
3.71v - 30%
3.64v - 20%
3.57v - 10%
3.5v - 0%


Hence why an LVC of around 3.4v is often suggested to ensure a resting voltage of 3.7v (20% capacity remaining in the pack)

And why people suggest you should only use 80% of a packs measured capacity

Cheers

some good info here. Thank you guys !

[QUOTE=TOM MAR;9921504]The Rev-Tech batteries I have came with a recommendation paper, they say not to leave a (their) battery fully charged state for more than 2 hours as this could cause cells to swell.[/QUOTE


Nice of them to warn you. Wonder if there is any science behind the 2hr figure?

Sitting at full voltage is recognized as one of the things you don't want to do with your lipos.

[QUOTE=Duster_360;9925611]+1 It was nice of them, 2 pages of do's & dont's.
We run 1 cell in both oval & World GT on road, & voltage is everything lol.
I got 2 packs in April & they still are within a lap of new. (Following their directions)
I don't know if they are right, just the slightest indication of swelling.
But it makes me feel better.

Next time I talk with them I will ask how they came up with 2 hours.

But I have a first run 5000 Thunder power 2 cell (3 or 4 years old) kept at 7.4 volts for long periods at a time (3 months between uses) for off-road. Ran them last week in SCT Stock ran 3rd in the A main.
Noticeable but slight swelling.

Tom

If you routinely do that, may want to consider putting the lipos in a ziploc bag and in the refrigerator - like the veg crisper and let them sit at 38-40F. You need to pull hem out ~24hrs before needing them to let them come back to room temp - leave them in ziploc so any condensation will be on outside of bag, not inside the lipos.

I've been away due to work and mine are sitting in a frig atm. The colder temps seems to suspend lipo aging process. Typically, 3yrs is about the age where lipo media begins to show signs of degrading.