levtron wrote:Question for whom ever:
offpist configured the Nissan battery modules as 10p7s (and since each module is actual 2s...the configuration is actually 10p14s). In his arrangement each BMC line is monitoring groups of 10 modules rather than individual batteries. Is there any problem in doing this....might a battery fail, weaken and not be detected...or perhaps not charge as well as it's neighbors? It certainly would be expensive to monitor each module...each module would need 2 BMS lines. If anyone has a thought I would appreciate hearing from you. Thanx...In Oregon with Nissan Leaf Battery ready to configure.
When you have multiple cells in parallel they act as one huge cell because all the minus (-) terminals are tied together and all the plus (+) terminals are tied together. If one cell in that group is not pulling its weight, it simply drags down the group. If the BMS indicated that one group in the series string was lower voltage than the rest, you could pull it out of the pack, separate the cells and test each one or charge them in series to find the poorly performing one. This is the reason that the OP put the cells in parallel and then put the parallel groups in series. The other way, that uses 10X more BMS, is to make 10 individual series strings and put those in parallel. That would be a huge expense for not much benefit.