[NSRCA-discussion] Charging Li-Po's

[Bob Richards]

Ken,
   
  Glad you dodged the bullet!!!
   
  BTW, could you tell if the pack was hot? Just curious.
   
  I have the same charger, and have been pleased with it. I purchased two temp sensors for it, just as an added safety measure. It will shut off if the temp gets too high. I also charge in an ammo box. I have a TP balancer that I use to check/balance my TP packs. For my non-TP packs, I use a voltmeter to check the cell balance before I start charging, and afterwards as well. I plan to get a Blinky balancer, and am looking for a plug/adapter for the TP balancer so I can use it with non-TP packs.
   
  I suspect you may have had one cell in the pack that was lower than the rest, causing at least one cell to overcharge.
   
  I read somewhere that if the open-circuit voltage is below a certain value (3.3v? -- can't remember off the top of my head) then you should start out with a low charge rate.

Ken Thompson <mrandmrst at comcast.net> 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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