Leaving a charge on lipos?

[bdebde]

I was wondering if it is ok to leave a lipo fully charged for a week or two? I am new to lipo and still learning.

I was waiting on parts for my truck in the mail. I got home from work and saw the box, so I threw the lipo on the charger and then ate dinner. I threw the balancer on it and brought it right up to max voltage. After dinner I opened the box and BOTH parts I ordered were wrong (one was my own fault though). So i gotta wait a week for the right parts and I have a fully charged lipo sitting here.

I can't run it in the truck, well, I could run it with only part of the drive train and certainly not with tires (busted dogbone). I don't have a lipo discharger, I do have other dischargers for nimh (bulbs, charger w/discharge), but nothing with a cut off for lipos. Is it ok to leave it like this then just run it when I get the truck back together? Is there a time limit on leaving a full charge on them? Of course they would eventually drain down on their own. Or should I try to discharge it to 50% using charger with discharge function until I use 50% of the mah? If I do that, what discharge rate would I use(discharger goes to 30A)? I guess I should say what the batteries are; 3800 mah Apogee limn, which may make a difference over normal lipo. They are rated @ 76 amp continuous output.

On a similar (or opposite) note, how long can you leave a lipo discharged (at minimum voltage) before charging it? I know lipos should be stored at 50% charge and maintained at nominal voltage if stored for extended periods. Just wondering what you guys do, throw a charge on them right away, or leave them at minimum voltage for days before charging?

Sorry for the long winded post:010:

[MetalMan]

It's best to keep Lipos stored at half capacity, around 3.80v. Storing them fully charged can cause them to lose some capacity, thus shortening their overall life. You can discharge Lipos on devices used to discharge NiMh, and monitor the voltage of the pack with a voltmeter. Disconnect the discharger when the pack gets to 3.7v/cell. It will rebound its voltage a bit, and it should be fine stored at that level.

[jhautz]

I store mine for a week or 2 at a time charged. I havent seen any bad effects. Although I try not to leave them sit at full charge longer than that. I just toss em on the discharger at 5 amps for a half hour just to take the top off of em and then put em away again. Although, they rarely go unused for that long.:018:

[hyperasus]

I've never heard of this. This is horrible news for me. I always keep my lipos charge. Some of them sit for months at a time fully charge. Had no idea this was wrecking them.

[MetalMan]

It's not necessarily "wrecking" them, it's just shortening their lives. Several chargers offer a "storage charge" feature where the charger charges to about 3.8v/cell. Here are several of these chargers:
-TP1010C
-TME Xtrema (voltage can be adjusted to whatever you want)
-FMA CellPro 4s (balancing charger)

[glassdoctor]

The ICE can also be set to a % of capacity charge.... so it will cut off the charge at that point. This won't help if the pack is only half dumped of course, but then you don't need to charge it anyway. :)

[jhautz]

Originally Posted by hyperasus

I've never heard of this. This is horrible news for me. I always keep my lipos charge. Some of them sit for months at a time fully charge. Had no idea this was wrecking them.

Dont freak out. Its nt that big of a deal. I kept the Lipo on my mini-t sitting at full charge for like 6 months cuz I broke it and never got around to fiing it. When I finally did fix it, the lipo still had a 95% percent charge and there is no difference that I can tell. The really bad thing for lipos is storing them fully charged and then exposing them to heat like in a parked car in the summer. About the worst thing you can do is charge up your packs and then leave them somewhere hot. At normal room temps you probably will not have an issue, but considering what theses packs cost, I just like to play it safe. Know what I mean.

[hyperasus]

Would it be better to keep them in a fridge when I'm not using them for long periods of time?

[tom255]

Actualy i heard that store lipos in fridge may help last longer. Ofcourse not in minus degrees of celsius, but bit higher +3*+6*c. Some guy in one forum had 2 identical lipos one allready died (puffed) but second one still going strong and he stored it in fridge. I dont know is that realy truth or just coincidence but i belive that! Becouse lipos die in high temperatures this is fact.

yea, dont put them in the freezer, but in the fridge they should last longer according to the manufacture.

[BrianG]

For car use, maybe get one of those peltier-based mini fridges made to run off 12v. Or, get the raw peltier units and then attach it to a metal box for ultimate protection against flaming.

Good way to keep them cool and protected. :)

[seth556]

This is good advise for me. I guess I won't store my lipos with my other rc stuff because the temperature ranges from 50 to 100 degrees there.

[hyperasus]

Not a bad idea. I think I'll build me a box like Brian G is talking about. Keep the batteries cool, and be firesafe. I could even make it fit the DC power supply and chargers. With handles on it for portability. Cool idea I like it.

[BrianG]

If you get the peltier unit, make sure you get a heatsink for the "hot side". The device gets hot on one side and cold on the other. Since you are putting the cold side on the box, you have to get rid of the heat on the hot side with a heatsink and maybe a fan.

[hyperasus]

I'm a computer overclocker so I know about peltiers. I have lots of heatsink/fans to play with. I'm just trying to think of were I could find a suitable metal box. I want something I can make portable so I can have my chargers and everything built in to the box. Maxamps should design one of these to sell on their website LOL.

Well I can dream cant I.