Mercedes C350 Sport Plugin Hybrid battery teardown

I bought this pack from ebay for the bargain price of £487.50. Many dismantlers who advertise on ebay chance their arm with pretty steep prices, so this was a good find.

Key Specs

Car Model: Mercedes C350 Sport 2014
Capacity: 6.38 kWh
Power Output*: 60 kW (* as per specs of the Mercedes)
Voltage: 290 V
Capacity: 22Ah
Weight: 100 kg
Cell arrangement: 88s1p
Width: 106 cm
Height: 12 cm / 17 cm (there is a chunky reinforcement beam near the back hence increased height)
Depth: 61 cm
Dimensions are approximate!

No teardown?

When this arrived I had a crazy idea that the whole thing might juuuust fit into the front (frunk?) of the Fiat. After failing miserably at hoisting it up into the air with a pulley, I gave up and made a cardboard template of the main shape and tried it for size. Alas, it was a few centimetres too big, so on with the teardown.

On with the teardown

The battery case is steel and formed from two halves bonded together. There are bolts on both sides of the case but these do not hold the lid on, they secure the batteries in place. The top is bonded to the bottom with glue containing a copper mesh. I learned that this is to electrically connect the upper and lower parts. The only way to pull the battery apart was to pry the lip of the top part with a screwdriver, cutting through the glue and copper mesh as I went along. This battery is evidently not designed with maintenance in mind.

Quirks

The sticker on the pack says 290V but usually, the nominal voltage of a lithium-ion battery is assumed as 3.7 V, so with the 88s configuration we would expect to have a pack voltage of 326 V, with min and peak of 264 V and 370 V respectively.

After stripping everything out of the case, I weighed it and found it to come to around 20 kg - which is 20% of the pack weight, quite a hefty weight penalty, especially for a plugin hybrid.

TODO get more pictures of separated modules. Put together video.

Thanks for reading and hope this was of some help to someone. If there's any other info you'd like about this battery, just leave a comment below and I will do my best to answer!