methods wrote:I bet that if you had a meter on all of the individual banks you would have seen that the damaged banks where showing a much higher voltage than all the rest.
I recently tested one of these hardcases specifically to find out what happens to 0V cells that either wouldn't hold charge anymore, or were just puffed but behaved normally. Upon 1.5C charge, the bad cells held a voltage of about 2V while charging, but dropped back to zero in a matter of seconds after I stopped the charge. So each cell was dissipating 15W heat, but eventually they'd start holding some of the charge I gave them, and got to 3.5V by the time the good ones in series already got over 4V. The weak cells were dangerously hot and puffed, but didn't pop. Then I let them sit and watched ALL of them lose voltage, the leakers and keepers alike. About 10mV per minute.
It seems that using these cells would soon result in a situation where they'd get to 0V while others were fully charged, thus overcharging all the other cells, or popping the weak cells from heat. Though they proved to be quite heat resistant, an enclosed pack of stacked cells would've helped them pop much sooner.
methods wrote:$3 for one of those cheap ass Hobby City beepers - buy 3 or 4 of those and plug them in.
That will save your ass next time
Just dont leave them plugged in all the time (while storing)
While they're handy little devices, it's not a good idea to slap them on all the riding time, then bulk charge. They tend to unbalance cells quite badly. Treat and know your cells so you can trust them and not just worry all the time.
I've had much more luck with conservative pack level LVC and cell level monitoring before and during charging (about mid charge).
I also use these on all my (and friends') builds.http://www.ebay.com/itm/Digital-Voltmet ... 0904901912
...and stop at 3.7V per cell unloaded.