Re-use Samsung SDI BMS?

[Matthew Dresser]

Hi guys,

I recently acquired the battery from a Mercedes C350 plug-in hybrid (6.3 kWh / 290V / 22Ah) for my EV conversion (for a Fiat 126) see here https://www.matthewdresser.com/ev/conve ... troduction.
The pack as-is is too large to fit anywhere in the car, so I am breaking it down into smaller components (and plan to re-use as much of the gubbins as possible).

Has anyone been able to re-use a Samsung SDI BMS before? I would assume this stuff is used in other cars as well, but not 100% sure.

[tom91]

first would be to track down a wiring diagram. If it has canbus it be worth not tearing the pack down to far so you can try and get some captures off the bus with the master powered up.

[boekel]

I've heard it's an spi signal.

two wires between slaves and to BMU

[tom91]

If you could open a slave and post pics of the top and bottom of the pcb. Then we can see what sort of chips are on it.

[Matthew Dresser]

@tom91 thanks for the replies (and you too @boekel) will grab some pics tomorrow evening - or as soon as work/kids/sleep-deprivation permit!

Excuse my ignorance, but are the BMS slaves within the part with the 8 connectors? (4th picture)

I'm keeping pretty much everything intact. I've split the batteries into two separate blocks but will not be ripping the cells off the cooling plates.

[tom91]

Slaves are the ones to which the Cells/modules wire into. so the 4 pic, the 4 'identical' looking boxes yes.

[Matthew Dresser]

Hi @tom91

Here are some more pics of the BMS parts, with the covers prised off!

[Matthew Dresser]

@boekel as you mentioned, there are indeed two wires between the BMS slaves.

[tom91]

Okay so this will most likely be ISO SPI comms. as these are LTC6804s.

Can you take the slave PCB out of the housing to check the bottom.

These should be re-usable, but someone would have to write the code to control them.

[Matthew Dresser]

Hi @tom91,

Cool thanks for the info! Will grab some more pics of the underside of the slave PCBs.

[tom91]

How is the battery module wired in?

I actually might have the right bits to talk to these slaves to hand, How good are you with Arduino?
Otherwise you could always arrange to bring some of the bits by me since your about an hour away.

[Matthew Dresser]

Hi @tom91,

Here's a pic of the underside, not particularly interesting...

[tom91]

That is good because that would mear it does use the ISOSPI as expected, just need too figure out if the first module, the one with more wires to it uses normal SPI or something else.

[Matthew Dresser]

Hi @tom91

Here's a pic of the underside of one of the slaves: