How Repairable Will Structural Battery Be?

[theganjaguru]

I am curious how repairable the structural battery will be. I’m a big believer of reusing things.

Seems like the only downside to a structural battery is that it could theoretically be much more difficult to repair since it will be part of the vehicle structure. Thoughts?

 

[mblakele]

Remains to be seen. But here's a sample of recent discussion in the investor roundtable thread.

On Benzinga:

Elon Musk Shares Tesla's Unibody Repair Strategy
10:22 am ET October 8, 2020 (Benzinga) Print

Tesla Inc's (NASDAQ: TSLA) Model Y uses a new body, made of large single stamped pieces. This reduces weight, eliminates hundreds of parts, saves costs, and makes production faster. The question about collision repair is often asked.

Now, Elon Musk has shared how Tesla will tackle the problem of repairing one large structure in a car. The CEO says the crash absorption rails can be cut off and replaced with bolted-on pieces. Crash absorption rails are built into the car for the purpose of absorbing the energy of an impact. But in more serious accidents, other parts of the vehicle may be damaged as well.

The crash absorption rails can be cut off & replaced with a bolted part for collision repair

not gonna lie, that repair strategy sounds absurd. body shops are going to saw off chunks of the casted body, and bolt on new segments? i am very doubtful that will happen with any regularity or be remotely viable financially.

It's a good thing Teslas dont crash very often and will crash increasingly less often over time, because these battery structure and frame optimizations are reducing the modularity of the vehicle, and thus making it far more likely to be declared a total loss after an accident. the industry has been moving in that direction for a long time anyway, but these highly optimized designs exacerbate that trend to the extreme. ultimately it's a wonderful and revolutionary improvement, but decreased reparability is a legitimate downside.

I believe the opposite could be true, as other's have pointed out. If designed properly the outside casting will deform and absorb most of the force in most accidents. They will be removed from the central casting and new units bolted into place, possibly with high strength adhesives as well. This should reduce alignment issues and speed repairs. If the impact is so great that the main central casting is damaged that's a totalled vehicle no matter the construction method.

 

[theganjaguru]

Remains to be seen. But here's a sample of recent discussion in the investor roundtable thread.

Thank you. I’m more interested in replacing a battery due to failure than repairing from an accident. It seems either case though you’d need to cut the frame and bolt on replacements. Not optimal.

 

[mblakele]

Thank you. I’m more interested in replacing a battery due to failure than repairing from an accident. It seems either case though you’d need to cut the frame and bolt on replacements. Not optimal.

Hmm, I'd think it'll be possible to replace some or all of the cells without cutting into the cast part. I wouldn't expect it to be trivial; but then rebuilding an internal-combustion engine isn't trivial either. Cells should very rarely fail, so why optimize the replacement process?

Maybe there will be some debate around that, like the debate around iphone battery replacement ca. 2007. At the time many people thought they needed user-replaceable batteries like older phones had. Today most users accept the integrated battery design. It's still possible to replace the battery, but it requires specialized tools and most people wouldn't try to do it for themselves.

 

[JRP3]

Hmm, I'd think it'll be possible to replace some or all of the cells without cutting into the cast part.

The cells are supposed to be glued in place and part of the structure. I expect it will have to be replaced as a complete unit.

 

[mblakele]

The cells are supposed to be glued in place and part of the structure. I expect it will have to be replaced as a complete unit.

You may be right, and I expect rebuilds to require special equipment. But there’s glue and then there’s glue. The stuff Tesla plans to use could be structural without being impossible to remove. After all the cells will have to be recycled at the end of their useful life.

 

[JRP3]

Sure they'll be removable but probably not in a non destructive way. Recycling doesn't care about preserving pack integrity and cell function during removal. Tesla doesn't replace individual cells now, I don't expect that to change with the new packs. People tearing down Model 3 packs say it's really difficult to remove cells from the goo, and that's not structural goo.

 

[ThomasD]

Does Tesla have it's own recycling process for the batteries or do they send them to a facility. Are these batteries considered hazardous waste?

 

[JRP3]

They were working with Umicore in Europe and I think Toxco/Retrieve Tech in the US. With JB at Redwood that may have changed now.

 

[MP3Mike]

You may be right, and I expect rebuilds to require special equipment. But there’s glue and then there’s glue. The stuff Tesla plans to use could be structural without being impossible to remove. After all the cells will have to be recycled at the end of their useful life.

Even with the current packs, if anything beyond a contactor needs replaced inside the battery is sent back to the factory to be repaired/refurbished. (They used to provide loaners pack and then give you your repaired pack back months later, now they just give you a refurb pack and their done.)

I would expect this to be the same. The service centers job will only be to R&R the pack, they will do no repairs inside the pack beyond the PCS board(s).

 

[mblakele]

My biggest concern about the structural battery (which is great engineering- the battery is no longer carried like luggage, but rather displaces structural members), is after an accident where the pack took an impact, how long do you have before some type of anomaly appears due to a stress fracture or something else due to the accident? I doubt you'll be able to go back to the insurance claim months/years later when your battery takes a sh!t and have it covered. Just a "worry" of mine....

(From the chat thread).

 

[JRP3]

I'm fairly certain that any impact which would stress the pack would have resulted in a totaled vehicle anyway.

 

[insaneoctane]

I'm fairly certain that any impact which would stress the pack would have resulted in a totaled vehicle anyway.

Lots of shades of gray.... I don't think we can say that any impact that results in some micro - level, stress fracture, not as good as it was damage to the cells likely would have totalled the vehicle. This new structural battery pack with structural adhesives being stressed as a structural load bearing member with electrical components will need quite a bit of lifecycle and impact testing IMO. The adhesive selection alone will almost certainly be iterated over the years once real world testing results are in. I'm not saying not to do it, I'm saying it is difficult and the road is riddled with potholes along the way. With Tesla's high volume, a mistake requiring a pack recall could be very expensive.

 

[SSedan]

What if structural means load bearing, not that it is permanent member?

 

[JRP3]

Lots of shades of gray.... I don't think we can say that any impact that results in some micro - level, stress fracture, not as good as it was damage to the cells likely would have totalled the vehicle. This new structural battery pack with structural adhesives being stressed as a structural load bearing member with electrical components will need quite a bit of lifecycle and impact testing IMO. The adhesive selection alone will almost certainly be iterated over the years once real world testing results are in. I'm not saying not to do it, I'm saying it is difficult and the road is riddled with potholes along the way. With Tesla's high volume, a mistake requiring a pack recall could be very expensive.

I've been using lithium battery powered tools that see repeated impacts to minimally protected cells which result in no issues. I've dropped drills which were "totaled" and transferred their battery packs to new drills which keep performing without problem. Cells surrounded by structural adhesive are going to be much more durable.

 

[insaneoctane]

I've been using lithium battery powered tools that see repeated impacts to minimally protected cells which result in no issues. I've dropped drills which were "totaled" and transferred their battery packs to new drills which keep performing without problem. Cells surrounded by structural adhesive are going to be much more durable.

Fair enough, but there are FAR more cells and connections in a Tesla battery pack than your Dewalt drill.

 

[JRP3]

And they are FAR better protected.

 

[imola.zhp]

Remains to be seen. But here's a sample of recent discussion in the investor roundtable thread.

Similar things were said about the CFRP construction of the BMW i3 an i8. Videos when the cars came out went on and on about how easy it would be to repair.

Then reality caught up and these cars were totaled at the smallest of accidents because no one had the training required to do the repair work. Shipping a car back and forth to special body shops isn't really a thing yet, maybe it will be one day, but for now insurance companies just write them off and move on.

 

[mblakele]

Similar things were said about the CFRP construction of the BMW i3 an i8. Videos when the cars came out went on and on about how easy it would be to repair.

Then reality caught up and these cars were totaled at the smallest of accidents because no one had the training required to do the repair work. Shipping a car back and forth to special body shops isn't really a thing yet, maybe it will be one day, but for now insurance companies just write them off and move on.

That doesn’t seem like a good analogy because Tesla increasingly runs its own body shops — and its own insurance. Both are somewhat nascent today, but should mature around the same time as the structural battery.

 

[ThomasD]

Tesla won't be taking the losses in an accident. State National Insurance will