Battery care pre BMS for testing

Topics concerning OEM and open source BMSes
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FFMan
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Battery care pre BMS for testing

Post by 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 ?
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Phev rear motor, OEM inverter cabin heater and charger
BMW 9kwh & 12kwh packs
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Bigpie
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Re: Battery care pre BMS for testing

Post by 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.
VW Beetle 2003
Outlander front generator
Prius Gen 3 inverter (EVBMW logic board)
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FFMan
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Re: Battery care pre BMS for testing

Post by FFMan »

Bigpie wrote: Sun Feb 26, 2023 8:54 pm 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.
E46 touring
Phev rear motor, OEM inverter cabin heater and charger
BMW 9kwh & 12kwh packs
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Re: Battery care pre BMS for testing

Post by 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.
VW Beetle 2003
Outlander front generator
Prius Gen 3 inverter (EVBMW logic board)
Outlander charger
3x Golf GTE batteries
Chademo Charging
Outlander water heater
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