You could do it, but there isn't really an easy way to hookup BMS, probably better off finding the 60.8V versions of this if that is what you are looking for.Ignoring the management stuff, how possible does it look to disassemble these and make something like a 60 or 72V module?
Thanks, good to know. For what I'm doing, removing the OG BMS and soldering or welding on some leads would be reasonable. For the 60-72V scenario, I'm hoping it would only need one or two of these to deliver 500A for reasonably short bursts.You could do it, but there isn't really an easy way to hookup BMS, probably better off finding the 60.8V versions of this if that is what you are looking for.
I dont think it would be that bad. Seems to me you have 2 decent options:I'll probably just have to run wires straight from the cells, which would suck.
Those don't look like aluminum plates - they look like copper bars with the cell tabs folded over them and welded together. Any terminal should probably be attached to the exposed end of the copper, not the tabs.I dont think it would be that bad. Seems to me you have 2 decent options:
Either solder a wire into the power connection for the PCB (red) or drill and tap the aluminum plates on the actual cells themselves (orange).
I am not an expert, but I thought those welds look like friction stir welds, which made me think they would have exposed the underlying copper if those tabs were made of plated material. But that was just a guess.Those don't look like aluminum plates - they look like copper bars with the cell tabs folded over them and welded together.
No, the friction welds used in battery connections typically just join the materials where they touch each other, like a traditional electric spot weld; they're not friction stir welds that mix the materials to a substantial depth. Look at the tiny wires that attach each end of each 18650 or 2170 cell in Tesla module to the aluminum bus plate - it looks like the wire has been smashed onto the bus plate and stuck there. Anyway, this module is similar to any other LG Chem module of pouch cells, so the people who have worked with them at the cell connection level can confirm how the welds work.I am not an expert, but I thought those welds look like friction stir welds, which made me think they would have exposed the underlying copper if those tabs were made of plated material. But that was just a guess.
Yes, they're wired in series. Each of those visible connections is presumably the positive tab of one cell (one one side of the copper bar) connected to the negative tab of the next cell, supported and located (and connected to the BMS) by the copper bar. There are 12 cells in series, so there are module positive, module negative, and 11 inter-cell connections... there appear to be six here on the back and so the the other seven (module positive, module negative, and 5 inter-cell) must be on the front.Looking at this picture again, and I feel like we are missing something obvious. I also assumed we were looking at the back of the module, but now that I think about it, I do not see that the cells are actually wired in series... This would explain why there was no voltage - you might be measuring cells that are not connected anymore! I am starting to suspect that there must be interconnections on the reverse side of the orange cover plates? Can you post a picture of the front and back of the exposed modules, plus the inside of the cover plates?
These are 12S (not 6S) modules, so you do need 13 BMS connections, 7 of which (including the two terminal studs) are on the other (front) side.As for the BMS taps, Brian, wouldnt you need 7 connections for a 6 cell module? It is true that you will need one tap from the far side, but it has the terminal stud that can serve as the connection point, right?
If they are monitoring voltage, though, then they should show voltage relative to somewhere, right? If those solder joints show no voltage relative to each other, then they must not be connected to the copper bars that hold all the cell tabs. I am not sure what purpose they would serve in that case. I assume the OP verified that there was voltage between the sets of tabs/copper bars? At any rate, hopefully more pictures and an update will make things clearer.I can only guess that the soldered points have no voltage relative to anywhere because they are some sort of isolated intermediate point in the monitoring circuit for each cell.
Yeah, I think you are on the right track. The outgoing harness (1) is probably connecting all the modules to a CAN bus, so it would not need to pass the voltages; it would just send data.I am going to call board b the battery balancing board, I assume it is only to use resistors to make sure all the batteries are about the same voltages. I pinned out #1 to see if there were any voltages, but there were not, it is only an 8 pin connector, so I wouldn't have the 12 voltages needed plus ground.
Thermistors are pretty easy to identify - they will be a pair of wires that read somewhere around 20k ohms across them. The exact value will depend on ambient temperature, and they do come in different ranges, I believe, but I think 20k is a pretty common value.or the thermisters, either way I don't know enough about those technologies to use those
I'll check voltages against ground first, if no voltages, mabe I'll get brave and try some resistance measurements across the side ribbon cables and see if that is what they are.Thermistors are pretty easy to identify - they will be a pair of wires that read somewhere around 20k ohms across them. The exact value will depend on ambient temperature, and they do come in different ranges, I believe, but I think 20k is a pretty common value.
Hmm, which plug might you be referring to? There isn't internal cooling, like it's 60.8V LG Chem big brother, I'll need cooling plates on the bottom.Do these battery modules have liquid cooling? Is that what the plug is on the left side?