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I ran across these two interesting videos on YouTube recently and thought you all might be interested in taking a look into the battery removal and disassembly:

- Removal

- Disassembly

Get out your popcorn, sportsfans!
 

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I have been thinking of asking an admin for a Weber Auto Bolt Techinal thread and making it a Sticky. Weber will have many more videos coming on the bolt as he takes everything apart including the motor and the controllers etc.
 

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I have a question for him, I wish he would answer. Why does GM bother running a separate charge cable to the battery for 7.68 kW DC charging from the HPDM, when they are already using the big cables for much higher power DC going in and out of the HPDM? The DC coming out of the on-board charger is going into the HPDM, to a relay, and then out another small cable to the battery. The DC from off-board DC chargers is going into the HPDM, to a relay, and then out the big cables to the battery. I am guessing they don't want any chance of big DC current getting back into the on-board charger somehow.
 

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I have a question for him, I wish he would answer. Why does GM bother running a separate charge cable to the battery for 7.68 kW DC charging from the HPDM, when they are already using the big cables for much higher power DC going in and out of the HPDM? The DC coming out of the on-board charger is going into the HPDM, to a relay, and then out another small cable to the battery. The DC from off-board DC chargers is going into the HPDM, to a relay, and then out the big cables to the battery. I am guessing they don't want any chance of big DC current getting back into the on-board charger somehow.
Two completey separate charging systems. One is 120v/240v @ max 32a which will need circuitry to charge a 390Vdc cell pack. The DCFC system charges at cell pack actual voltage (the same voltage as delivered to the motor through the motor controller) and much higher currents 100-150amps
 

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Two completey separate charging systems. One is 120v/240v @ max 32a which will need circuitry to charge a 390Vdc cell pack. The DCFC system charges at cell pack actual voltage (the same voltage as delivered to the motor through the motor controller) and much higher currents 100-150amps
The onboard charger charges at actual pack voltage too. The input to the charger is 120-240 volt AC, of course. The DC output is whatever it takes to deliver 7.5 kW DC (unless you are using the OEM portable EVSE) to the battery pack. Near full that is about 400 volts at 19 amps. Near empty it could be 255 volts at 30 amps. The battery doesn't know where the DC power came from. The High Power Distribution Module decides which relay to close to deliver that power. It could just a s easily come from the big external DC charger, or the little on-board DC charger. So my question remains..."Why bother with an extra cable from the HPDM?"
 

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That was fun! I loved his teardown of the relays at the front of the pack. Had to chuckle seeing the pre-charge circuit. My homebuilt, 58.8 volt, seven Leaf module cargo bike battery has a pre-charge setup too. It is all connected manually, without relays, but works exactly the same.

There was one thing which I found frustrating. There are five sections to the battery, each with two modules. Eight of the modules are 10s3p, and two of the modules are 8s3p. In a GM video, the battery engineer pointed at the smaller aluminum boxes in each module, and called them cassettes. He said there are two cells in each cassette. There is one wall of each cassette in contact with each cell, to act as a thermal path to the cooling plates. In the Nissan Leaf each cassette, which Nissan calls a module (confusing right?) has four cells in a 2s2p configuration. GM has two cells per cassette, but 3 cells are welded in parallel, which means you cannot pull out an individual cassette. They would have to come out in a groups of three, which is a hassle if you wanted to repurpose them. Anyway, when you look closely at the modules in the video, you should see 15 cassettes in the 10s3p modules, and 12 cassettes in the 8s3p modules. However, I count 14 and 11 cassettes, and a sort of ambiguous section at one end. It is hard to imagine that they would have one odd design cassette in each module. And if so, to what purpose? Looking at the end shot, as you see in the still before starting the video. That end cassette doesn't look as thick as the others. It doesn't look like it could hold two cells. I wish he had been able to tear a module apart as he wanted to. Oh well, pretty neat anyway.
 

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Anybody else watch the next video? Near the end he shows some screens from the GM diagnostic setup. He said he will do a whole video showing what you can learn about the battery from the diagnostics. He says he will be tearing down the individual parts of the drivetrain too.


His battery was charged to "hilltop" on a 240 volt EVSE, before he tore it apart. The diagnostic screen shows it at 88%, 387.92 volts, cells ranging from 4.02-4.04 volts. It shows full as 402.48 volts (4.1925 volts per cell), and 1% as 241.28 volts (2.5133 volts per cell). Clearly, GM is wringing every bit out of this pack!
 

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For a DIY version of the disassembly:
Person got it salvaged from a Bolt w/7k miles on it. I think they're planning on reselling for profit.
 
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