So as previously posted I bought my prius with a bad traction battery...bought 2 1/2 2nd gen units one was a just totaled 07 with 49k and other 2 where less then 100k from 05's.. I load tested and balanced the cells, built my pack out of the best ones and went on about my day.. Since then I had 1 cell quit...No problem right? Well suddenly we've lost 7 cells and one was the top literally blowing the negative side cell casing apart. Now I've have an additional pack(in parallel) that I can command via a contact switch from one of my ev projects, only to boost my electric only take offs and occasional parking lot boredom laps. Am I missing something ? Thanks in advance Have fun ! Eric
We need photos and a schematic. That 7 modules failed and one with a terminal failure suggests the modules may not have been balanced. How did you handle the 19 module pair, sense wires? Bob Wilson
Photos to come works been insane and I just had a short time yesterday to take a quick peek. Have fun ! Eric
I have been thinking about module balancing and I keep coming back to: manually charge each to the expected maximum voltage - balance at max V is critical next wire all in parallel - the oldest charged one will have self-discharged down a bit tickle the massive set to the maximum - this over comes the (I**2)R residual between modules Now a relatively weak module will during discharge lose more voltage and possibly trigger the 0.3V threshold error. But at least when the traction battery is charged, it minimizes the risk of gas generation in a module blowing out a terminal . . . (not the over pressure safety seal?) It really is critical to have the aHr capacity for modules to be as close together as practical. The reason is the lowest aHr capacity modules will have the largest, voltage change of the charge-discharge cycle. Bob Wilson
