catfish2

My Feedback: (43)

I have several 2s packs made with Dewalt cells, both 2300 and 1100 VPX for use in my planes. All of these packs were assembled within the last few months, some by me, some were purchased. I am using the new fma multi-4 charger to balance charge these packs. I have two packs now that will not balance. One cell is consistantly reported as about 3.4 volts the other in the 3.6 range when the charger says its done after about 30 minutes. (the majority of the time is spent in the balancing cycle)

Is this a serious issue showing that the packs should be tossed? Or should I continue using them? For the moment I am continuing use on my planes that are using dual battery packs, figuring that I have a backup just in case. So far no noticable change in the total battery drain after a flight session. Total ma's put back in each pack during charge has remained consistant.

If this does show the packs need to be tossed, how would users charging with nonbalancing chargers like the formeco cube know?

soarhead-RCU

I have been useing the 1100ma cells in 2s and 4s packs and it took them quite a few cycles before they "settled down" (5 to 10). I use the 2s for RX power in sailplanes and fuel jobs and 4s as power packs with sailplane with power pods. Charles (everydayflyer) has done a lot of research and testing on these cells and he bench cycles his several times before he even uses them. The imbalance in the discharged state is normal for mine but come in as they are charged. I very seldom have to balance them at all now and have many cycles on them. They are great for my use!!!

Good Luck
Bob

catfish2

My Feedback: (43)

I posted the same question in the "other" site. Responders suggested I discharge/charge the packs down to a nominal 6 volts.
I did this several times with no changes to the 1100 pack and even drained the voltage down further. In doing this I did determine that the overall capacity of the pack has been reduced to about 700-800 mah. It appears that one cell in the pack is not up to par.

I will keep this pack for use only for benchwork, a 25% reduction in capacity is not something I want to risk in the air. The other 2300 pack mentioned in the original post responded to the cycle treatment and was put back in service.