opinions about batteries....

[nativepaul]

Just this week I dug out 2x turnigy and 1x zippy flightmax 30C 4s 5000mAh packs from storage, where they had sat untouched for 2 seasons due to getting higher capacity packs at the end of '09, the first one gave an error on the charger (too low voltage for the balancer) I put my voltmeter on the pack and it read 8.5V, i tried it without the balancer but it errored again (output low voltage), so I told the charger it was a 3s pack and charged it without the balancer for a few mins, when the voltage reached 12V I stopped it, plugged the balancer back in and finished charging it as a 4s pack as normal, I was holding the pack throughout to monitor for heat or swelling but there was no sign of either, it put over 5000mAh into it as normal, it did take just over 2 hours at 1c though due to a large imbalance on one cell (170mv), although I didn't put the voltmeter on them the other 2 couldn't have self-discharged as far because they charged normally to over 5000mAh straight off, but while not as bad were further out off balance than I would normally expect at 46 and 72mv. I was half expecting them to fall apart under load, but the 2 i have run so far (inc the 8.5v one) seemed to have as much punch as I remember and are still worthy bashing packs.

Rating voltage while simple is not enough, you need temperature in there as well, if capacity and voltage are all that matters you get good performing cells which get hot and only last a few runs, that was the worst thing about NiMh IMO, and are starting to get it again with LiPo boating in boat racing which calls for both high energy and power densities.