[NSRCA-discussion] Charging Li-Po's

[Chad Northeast]

If your packs are 3.3-3.4V/cell resting (or lower) you should intiate 
the charge very slowly (1/10C) until they come up to a nominal voltage 
(3.7/cell).

You should also be storing your packs at about 3.8-3.85 v/cell.  For 
best life you dont want to see open circuit voltages below 3.7 v/cell.

Chad

Ken Thompson wrote:

> We've all heard the stories, here's mine that I posted on the Flying 
> Giants,
>  
> Ok folks,
>
> This is the deal...
>
> I am finishing an Extreme Flight 300-E. I want to run 2100mAh 3-cell 
> Li-Po's, so I grab the 2 I already have and check them out. One has 
> almost no charge at all, I kind of knew that already, I had trouble 
> with this pack last year. The second one showed about 9 volts and 
> change. I hooked it up to my Accu-Cycle Elite and went to do a 
> discharge so I could check full capacity on the charge cycle.
>
> The charger told me the pack was discharged already, so I set it up 
> for a charge and let it run for 20 min. or so, just to make sure it 
> was working ok, everything looked good so I let it charge and went 
> inside. Now keep in mind this battery is sitting on a wooden bench 
> next to my Pattern plane and my new Extra.
>
> I went out in the garage this morning and heard the charger doing 3 
> fast beeps, pause, 3 fast beeps. I said,"Oh, shoot!" and went to the 
> bench, the pack was 2.5 times it's normal size!!! I didn't think to 
> look at the charger to see what the screen said, I just shut it off, 
> unplugged the pack and ran it outside and threw it on the lawn. I went 
> back to the pack in about 5 min. and cut the Deans connector off, 
> can't waste one of those, and the pack will sit out in the rain all day.
>
> Now before all of the comments come like,"You should know better than 
> to charge Li-Po's without them being in a can!!!!" I know, I know...
> I've been using Li-Po's since the first Kokam packs came out, never 
> had a problem charging them, never even got warm. This is the first 
> time I've used this charger on them, so I think I must have done 
> something wrong.
>
> Now I need to make a trip to the LHS and spend a couple of hundred 
> bucks on new 2100 mAh packs, this time with balancers.
>
> I dodged a big one this time!! I never even checked to make sure the 
> house insurance was paid...by the grace of God, it's only the pack 
> that was destroyed.
>
> This could have been a very bad day, folks, PLEASE take this as an 
> additional warning when you charge your Li packs.
>
> Flame suit on, go ahead...I've got it coming.
>
> It sure helps a ton to go to church and say my prayers!
>
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>
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