BMW i4 battery 84 kWh

[boekel]

to be opened...

[boekel]

part 1

[boekel]

part 2

[boekel]

part 3

[boekel]

part 4

[boekel]

so:
4 big blocks with each 2 modules of 12s 18.7kWh
3 small modules 4s each, 3.11 kWh

210 Ah

cooling integrated in each module

for sale here:
viewtopic.php?t=4765

[m.art.y]

so:
4 big blocks with each 2 modules of 12s 18.7kWh
3 small modules 4s each, 3.11 kWh

So how many cells in series total that is? And in parallel?

[tom91]

3 in parallel 108 series (3x4 + 4x2x12)

[johu]

I don't quite understand. So the 4 large rows are 96S (4x2x12S). But where are the 3 small modules? I only see one

Your measurements would be roughly
1288x370x85mm for the 4 large bricks and
450x190x82x85 for the small brick(s)

That will require a unique vehicle. Or a boat

Anyone wants to add to wiki?

[evMacGyver]

But where are the 3 small modules? I only see one

2024-02-29 16.08.07.jpg

Missing two was hidden here

Interesting, I might have "boat" for these. Could be the same CAN messages as another BMW ones, but not verified?

[boekel]

Missing two was hidden here

Interesting, I might have "boat" for these. Could be the same CAN messages as another BMW ones, but not verified?

I suspect a 2-wire comms:

[evMacGyver]

This is interesting and bit dangerous design, as there are no separate BMS boards on every battery module, here every battery cell wiring is connected to one big BMS module. Module isolation for measurement is done on BMS board.

This is kind of hazard, because those are low voltage connectors and if you touch different connector pins connected far from each another on the pack you might be exposed to high voltage if battery pack main HV cables are connected between modules. I hope there are proper fuses near every cell before wiring, but on the another hand is there many very low current fuses available with high DC voltage rating? Also could end up to very bad high voltage DC arc between wires if cell fuses would not extinguish arc properly. Rare risks but possible I think.

Plus side this design would allow active balancing on entire pack, eg. current moving from cell 3 to cell 103 and vice versa. Not impossible but I doubt active balancing, it would require SMPS transformer near to every module isolation component and depending on the design perhaps more transformers on every module circuit.

Has anyone seen this kind of design before on BMW packs? BMS could talk nicely to CAN similar protocol as other BMW packs, or not.

[boekel]

Other BMW designed packs (like the Mini) also have the CMU's not too close to the modules. very common. And yes, most have fuses on the modules. (nissan Leaf does not for example)

For me it also makes more sense to have the CMU's on the modules, but for some reason they don't.

active balancing is really not a thing in normal batteries, if cells require more balancing than the tiny current the car batteries can balance, the battery is bad and needs replacing.

[johu]

active balancing is really not a thing in normal batteries

Much agree, solution in search of a problem

I also think the pack design is quite aweful. "Power of choice" doesn't really look well here. With the exhaust tunnel part removed and a less centralized BMS it'd actually be quite neat.