Electric Cars

[Jim Becker]

They couldn't plug a kitchen appliance into a 6-50 receptacle so unless the jurisdiction required appliance outlets in the garage (seems unlikely) it doesn't seem any different that providing a receptacle for a tablesaw or welder; it's just a higher capacity circuit.

I don't disagree with you, Greg. Let me clarify the "appliance" circuit comment for better context. For a very long time appliance circuits were simply two hots and a ground no matter what was at the device end. If the device needed a neutral, the appliance "took advantage" of the bonding between ground and neutral at the main panel and, um...just used the ground as the neutral, too. Many of us have homes that have drier outlets, for example, that were set up this way. Many older hard-wired ranges are similarly wired. Code changed to eliminate this practice so new "appliance" circuits need to have separate ground and neutral. There's no disagreement that a 50 amp EV charging circuit doesn't "need" a neutral. But that doesn't preclude an inspector/jurisdiction requiring it. That's all I'm saying. "local" matters.

[Brian Elfert]

Yes, but that's a different situation and I've done the same, honestly, because I hate waste and also hate spending money on something that I already essentially have. But in the context of this thread, we're talking a 50 amp 240 v circuit to charge an EV ... 50A 240v is typically a dedicated appliance circuit in residential settings and is required to be four wire, AFAIK. I do not honestly know if there's any specific consideration around EV charging ports in code and inspections. In the end, it may also come down to the inspector as "all approvals are local".

Wasn't the question if a four wire cable could be used to wire a three wire circuit?

[Greg Funk]

Touching on battery recycling and lifetime. Companies are already being formed and studies are already coming out about how efficient battery recycling is in the very near future. The reality is, battery rebuilding/reconditioning is going to be a big business for the future. These batteries are designed to be able to swap cells. When a battery "goes bad" it's likely that it will only be a cell or a few cells. Dropping the battery, opening it up, removing the bad cells, popping in new cells, balancing the battery, and reinstalling is going to be a big business in the EV world within the next 10 years.

Let's just hope the dealers are open to allowing other shops work on these vehicles. Right to repair is a big subject and could be a big problem in the near future with EVs. With EVs theoretically needing less repairs, it wouldn't surprise me one bit for manufacturers to limit the amount of info available to the public so that dealership service departments stay busy and profitable.

I think re-purposing used EV batteries will likely be a decent business at some point. A battery that's 50% of its original capacity may not be useful in the vehicle but could work well for many other applications where size isn't critical. As far as repairing batteries at the cell level, that's certainly not feasible in Teslas with thousands of cells wire bonded together. It might happen at a module level where a vehicle has 3 or 4 modules that make up a 'pack'. Mixing fresh cells with aged cells doesn't generally work well.

[Ross Moshinsky]

I think re-purposing used EV batteries will likely be a decent business at some point. A battery that's 50% of its original capacity may not be useful in the vehicle but could work well for many other applications where size isn't critical. As far as repairing batteries at the cell level, that's certainly not feasible in Teslas with thousands of cells wire bonded together. It might happen at a module level where a vehicle has 3 or 4 modules that make up a 'pack'. Mixing fresh cells with aged cells doesn't generally work well.

I'm not 100% up on the latest battery info, but I think ultimately they're going to have to be willing to address the batteries at a cellular level. It will probably be handled like any other automotive part. Get a re manufactured module. Slap it in. Send the bad module out. Get a core-refund. Someone repairs the core.

Big picture, if you have a module with batteries lets say 95% capacity and 3 cells that are at 50% and it's tanking the battery, there's no reason that they can't find 3 other cells with a similar max capacity and swap them in. Then take the bad cells and recycle them. Now you can sell the module at 95% capacity which would be great for most people.

It's hard to say if a battery that is worn out will be best recycled in it's current state as a power wall or something like that or broken down and recycled into "new" batteries. I'm not smart enough to know which is the best path forward.

[Malcolm McLeod]

I'm not 100% up on the latest battery info, but I think ultimately they're going to have to be willing to address the batteries at a cellular level. ....

I don't follow the technology closely either, at least not at this level of granularity, but I am betting the smart people have already incorporated a relay here, and a transistor or 50 there, such that a bad cell (i.e. dendrite shorted) can be isolated from the other good cells. The battery just keeps chugging along at slightly lower capacity.

As you outline, someone will have to repair the defects at some point - and on some level (cell, module, or the 'battery' in its entirety).

[Greg Funk]

I'm not 100% up on the latest battery info, but I think ultimately they're going to have to be willing to address the batteries at a cellular level. It will probably be handled like any other automotive part. Get a re manufactured module. Slap it in. Send the bad module out. Get a core-refund. Someone repairs the core.

Big picture, if you have a module with batteries lets say 95% capacity and 3 cells that are at 50% and it's tanking the battery, there's no reason that they can't find 3 other cells with a similar max capacity and swap them in. Then take the bad cells and recycle them. Now you can sell the module at 95% capacity which would be great for most people.

It's hard to say if a battery that is worn out will be best recycled in it's current state as a power wall or something like that or broken down and recycled into "new" batteries. I'm not smart enough to know which is the best path forward.

That's not how batteries typically age. For a well designed battery with high quality cells (as used by Tesla) all cells typically age at similar rates. Sometimes certain cells will degrade a little faster if, for example, a part of the pack gets hotter than other parts but it's relatively small variations and those variations are not really 'fixable' at the cell level.

Just so we're clear on definitions, when I'm referring to cells I'm talking about the individual Li-Ion cells used to make up a module or pack. Tesla uses the smallest 'cells' of any manufacturer - originally 18 x 65mm and eventually next year growing to 46 x 80mm. They package these cells into modules in the 90V range and then combine modules in series to make a complete pack for the vehicle.

From what I can see the packs and modules from Tesla have been very reliable and are aging well within the limits required by their warranty. Eventually they'll degrade beyond acceptable limits for drivers and they'll start replacing whole packs. I've not heard of Tesla replacing modules to date, and packs that are replaced are often due to some physical damage - rocks or accidents.

[Brian Elfert]

It is easy to buy Tesla battery modules from Tesla vehicles that have been in accidents. The undamaged modules are sold on the secondary market, often on Ebay. I don't know if a damaged battery is replaced entirely, or if just the damaged modules. Same with batteries from other electric vehicles although Tesla seems most plentiful. (I wouldn't buy a Chevy Bolt battery module with the recall.)

[Jim Becker]

It is easy to buy Tesla battery modules from Tesla vehicles that have been in accidents. The undamaged modules are sold on the secondary market, often on Ebay. I don't know if a damaged battery is replaced entirely, or if just the damaged modules. Same with batteries from other electric vehicles although Tesla seems most plentiful. (I wouldn't buy a Chevy Bolt battery module with the recall.)

True...there's a whole industry dedicated to Tesla batteries and drive systems from wrecks that are used to transplant into one-off show vehicles and concepts. It's not a straight swap however, because the Tesla software has to be hacked to make it work in a non-Tesla environment. One or more companies specialize in the software and firmware stuff to make that happen.