Battery care pre BMS for testing

[FFMan]

I'm getting to the point of my build where i can think about testing it gently. It's the E46+phev motor+prius inverter+V1c board with 9kw 96 BMW battery pack to start with.

Before i go down getting a/the bms to work, for gentle testing where i'm in no danger of over-discharging the batteries, should i just check each of the 6 packs is within a volt or two of each other. Should i think about separately charging each 60v pack stand-alone first to bring them to the same level ? Is this the same action i would take when i bring the SOC shunt into play ?

[Bigpie]

If they're from the same pack, they'll likely be pretty well balanced any way.
My new modules are from different packs so I'm painstaking charging and discharging to get the cells a bit closer together with a rubbish hobby charger. It's taking ages.

You can used voltage for an idea of SoC, I did for 6 months or so before getting the shunt but to run simpbms all you need is a teensy, can transceiver and a buck converter module on perf board.

[FFMan]

If they're from the same pack, they'll likely be pretty well balanced any way.
My new modules are from different packs so I'm painstaking charging and discharging to get the cells a bit closer together with a rubbish hobby charger. It's taking ages.

thanks - what is the maximum delta i should be looking for from highest pack to lowest. IIRC when i got them i tested them and i wasn't upset but i don't recall the figures.

is it safe to charge them to 4.2v per cell which is what the commercial chargers seem to charge to.

[Bigpie]

I don't know, mine are usually within about 50mV or less depending on SoC. I did get to point last year where 3 or 4 had gone to about 140mV so I charged the up a bit to bring it down. I've since got the BMS balancing.

I tend to charge to 4.11 iirc, don't think I'd charge to 4.2 but if I did it would be that I was driving right away and wanted a tiny bit more range.and not something I'd do often but again, I'm not an expert.