OneLapper
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I have some experience repairing modern 350vdc battery packs for the Alta motorcycles. These packs are said to have been designed by ex-Tesla engineers.
Like the new structural 4680 battery packs, the Alta battery packs epoxy the cells into the cell holder. The bottom of the module is an aluminum plate which is the heat sink. If a cell fails (haven't seen one individual cell fail yet), it's effectively impossible to remove and replace that cell without destroying the module.
The modules (4 in all, like current Teslas) have the cell grouped in parallels of 6 cells. If any wire bond breaks on any of the cells in the parallel group, all 6 cells within that P group are affected. In this case, the cells are no longer electrically connected to the module therefore they do not charge or discharge.
If someone noticed this failure soon enough, and they were able to physically repair the broken wire bond, the cells would resume their work and little damage would be done. What I have observed is that affected module falls out of balance with the other three good modules due to the 6 cells that are not charging and discharging. Over time that module slightly overcharges and over discharges.
With the new structural 4680 battery packs, there doesn't appear to be any "modules", therefore a single wire bond failure to a parallel group (unknown quantity of cells at this point), would result in pack with a lower overall voltage, and result in less range. As an owner, we would have no indication of a wire bond failure, save for a reduction in range.
Since the Tesla battery packs are glued and screwed together, they are not intended to be fixed. The 4680 pack will be "less" repairable than the existing 4 module Tesla packs. I've stated before, I doubt there will any way to "fix" a Tesla 4680 structural battery pack. And since there are no modules (that we know of at this point), the EV West's of the world can't pull the modules of a wrecked Tesla and sell the good ones for DIYers.
I don't know if any independent diagnostic software is available for Tesla's battery packs, but it would be nice to have. I'd love to be able to see the health of each parallel group in a Tesla pack.
Like the new structural 4680 battery packs, the Alta battery packs epoxy the cells into the cell holder. The bottom of the module is an aluminum plate which is the heat sink. If a cell fails (haven't seen one individual cell fail yet), it's effectively impossible to remove and replace that cell without destroying the module.
The modules (4 in all, like current Teslas) have the cell grouped in parallels of 6 cells. If any wire bond breaks on any of the cells in the parallel group, all 6 cells within that P group are affected. In this case, the cells are no longer electrically connected to the module therefore they do not charge or discharge.
If someone noticed this failure soon enough, and they were able to physically repair the broken wire bond, the cells would resume their work and little damage would be done. What I have observed is that affected module falls out of balance with the other three good modules due to the 6 cells that are not charging and discharging. Over time that module slightly overcharges and over discharges.
With the new structural 4680 battery packs, there doesn't appear to be any "modules", therefore a single wire bond failure to a parallel group (unknown quantity of cells at this point), would result in pack with a lower overall voltage, and result in less range. As an owner, we would have no indication of a wire bond failure, save for a reduction in range.
Since the Tesla battery packs are glued and screwed together, they are not intended to be fixed. The 4680 pack will be "less" repairable than the existing 4 module Tesla packs. I've stated before, I doubt there will any way to "fix" a Tesla 4680 structural battery pack. And since there are no modules (that we know of at this point), the EV West's of the world can't pull the modules of a wrecked Tesla and sell the good ones for DIYers.
I don't know if any independent diagnostic software is available for Tesla's battery packs, but it would be nice to have. I'd love to be able to see the health of each parallel group in a Tesla pack.
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