Spritzer2000 t1_je0i9up wrote
I don't have the pinout to hand, but it's fairly moot as you would need to move the BMS from the old battery to the new. Unless it handshakes, it won't receive power. Microsoft surfaces don't like receiving power at all without the BMs connected
lululock OP t1_je0j663 wrote
Yeah, that's what I was afraid of...
Any way to rip the BMS from the old battery without setting it on fire ?
Spritzer2000 t1_je0t4f9 wrote
Wouldn't be something I'd risk to save a couple hundred tbh. If the swollen cell is far enough away from it, maybe? If its badly ballooning, don't bother.
lululock OP t1_je0u634 wrote
The BMS seems to be located right between the cells. If I cut short each cell wires, there should be no short... But the cells doubled in thickness, I'm even afraid to remove them from the casing.
Spritzer2000 t1_je0vv80 wrote
I wouldn't bother attempting to create your own battery. Personally I would attempt to buy a battery from a reputed vendor (original is better but does not have to be), and if you have prior experience dealing with fire risk batteries, go full send next to a bucket of sand.
If its your first time, pay a reputed repaid shop, and start off with another, less risky repair
lululock OP t1_je0wt7o wrote
The tablet is already disassembled, thanks. I already dealt with similar devices to not break stuff while attempting a repair. I've just never dealt with such a bloated battery.
The idea was to fix that inherent design flaw the Surface Pro 4 has : A massive part of its heatsink is covering the battery and transfers heat to it, damaging it the more the Surface is used.
If I replace the battery, it will do it again in a few years if not sooner due to lower quality cells.
Buying good quality 18650 and making 3D printed parts to fit them outside the casing will cost less than a replacement part from Ifixit...
I not only want to fix it, but I want it to last longer.
Spritzer2000 t1_je0zb2o wrote
Ah excuse me I misunderstood the original intent. I can't pretend I understand your reasoning, as it sounds like a very non portable solution for a device that was sold on the basis of portability.
I would probably recommend buying the replacement battery and attempting to remove BMS from that rather than mess about with the spicy pillow
lululock OP t1_je1010x wrote
You're right... I guess I'll salvage the BMS from another dead battery which hasn't expanded yet. I'll ask a few repair places around. Maybe they could even strip out a BMS for me.
But then comes the part where I'll solder new cells to it. Do you think it will get the extra capacity of 18650 cells ?
Spritzer2000 t1_je151mq wrote
If it's done properly, I don't see why not. The only thing that might get in the way will be if there's an individual bms system in each cell that handshakes with the "central" system. I haven't actually cut into batteries in a while, generally only replace them
lululock OP t1_je163p2 wrote
I've found a picture of a BMS someone took appart.
The left one is from a Chinese copy but the right one is the original LG one. Looks like both cells would connect to it. Comments say that the original BMS has a temperature sensor and charging control and that's why some Chinese copies won't get recognized by the Surface.
I think I'm getting somewhere with my idea.
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