Designing Nissan leaf packs

[Nappe]

Hi everybody. So im running a leaf powerwall with the batrium watchmon as bms. Im reconfiguring it now since ive got a new batch of leaf modules. In that process im remeassuring my old packs and they have a higher iR than the new ones.
The older modules goes between 30-50 mOhm and the new ones are at 20 and below.
so my question is:
When i design the new packs i know i have to put those with aprox same iR together in the same packs. But the new packs also have a higher capacity. 40 a/h compared to 30ish a/h on the older ones. So in order to hit same package capacity is it ok to put 6 cells together in one pack matching iR of 20mOhm and 5 in another matching 40 mOhm as long as they have roughly same capacity?

 

[OffGridInTheCity]

Don't know but following with interest! Off the cuff, I'd suggest trying to make each parallel group of cells have the same overall IR - so that when you put them in series and charge/discharge current flows across the series they'll rise/fall more equally...

Here's why I'm thinking this....
I have 10 x 14s 18650 lithium-ion batteries in parallel (140 packs) and after 7 years (2,500 cycles) 2 of my packs in 2 different batteries have started showing imbalance during the charge cycle similar to self-discharge but I'm not sure it's self-discharge. I'm guessing IR?!?

These 2 packs (100 cells in parallel) don't 'charge up as fast' as the others at full charge - e.g. the other 138 packs reach 4.00v OK but these 2 packs seem to stall at 3.995v and since they don't charge all the way up they 'loose' (almost like self-discharge) 5mv / cycle so after a couple of weeks of cycles they are sagging 100mv and I have to boost charge them.

Now that I'm in winter and things aren't charging all the way up to 4.00v anymore they're seem OK. In winter the max charge averages 3.8v'ish instead of 4.0v. So one possibility (in my fuzzy? thinking) is mis-matched IR with packs in series is causing my issue and that IR mis-match is worse at 4.0v than 3.7-3.8v?. It's also 20F degrees cooler ambient in winter for the cells.

If you'll document what you decide and post the results - I'm following closely