Let's back up and explain a bit better. This is for a 2014 and similar Electric with an N82/2 BMS. I think it's 2008-2016? You'll have to clarify that, it's applicable to 2014 and all similar versions. Somebody please chime in here. On the battery repair, yes it's a little more involved. You'll drop the HV battery, which is actually quite easy, using 4 jack stands to support the car, a floor jack (2 is easier) , and a dolly to hold the battery on and move it around, once it's down. Remove a bunch of nuts, drill out a few soft aluminum rivets, some additional screws and a coolant fitting, and then separate the cover carefully, as there is sealant between the flanges. I used a hammer and a sturdy putty knife to slice the sealant, it was easier than it looks. Pop the cover, and disconnect the current sensor immediately (just the data connector). BE CAREFUL OF HIGH VOLTAGE - don't do this if you aren't knowledgeable of high DC voltage- use rubber gloves, etc. Now slowly recharge the cells, preferably using a constant current/constant voltage benchtop lab supply or similar, so you have total control over the max voltage, and current, starting with no more than 100mA, till they're above 2.0v or better. Then increase to 200mA, up to say, 3v, and much higher amps are permissible near the working voltage. The cells are very robust, and likely they will all come back up to normal voltage. Mine did, so did those of most others I spoke with. On the rare occasion one or two cells don't, you've either a pile of spare parts, or you'll want to source some spare cells. Note that unlike Tesla, or Prius, and similar batteries, these cells are a bit difficult to remove, and they're ultrasonically welded with flexible copper/aluminum ribbons, so it's a bit tricky. I understand some are having success with it, I have no experience yet, mine recharged just fine. There's a guy on Youtube doing solar storage stuff, I know he took some apart successfully, so I'd start there. Remember, the current sensor is very susceptible to failure, because the DC-DC converter loses its cotton picking mind and spits our large overvoltages, when the 12v drops excessively. This is the cause of the failures in the first place. It's a Mercedes Benz "feature" (ugh). So there's a chance the sensor may be toast, along with possible parts inside the BMS itself and the aforementioned cells perhaps. Thus far we've been able to fix most BMS issues, and a friend in Germany is almost done cloning these current sensors, using similar (but with different firmware inside) Bosch sensor. So soon nearly all will be repairable ourselves, and the rest, with spare parts from wrecked Smarts, will also be repairable. I know of one owner with a wrecked Smart, she's got spare good cells right now for sale. Hit me up if you need more information. Or you cam start the well deserved class action lawsuit against MB.
