# Body panels that are also batteries



## rochesterricer (Jan 5, 2011)

This strikes me as being best for hybrids or stop/start applications. I don't know if having every body panel being a battery is a great idea.


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## PhantomPholly (Aug 20, 2008)

First off, they are capacitors not batteries. Not bad for regen braking recovery, but not a lot of energy density.

Second, if thinking of a vehicle as a warrior, you want to protect the vitals. Putting batteries in the skin may save a few pounds, but you've now made the entire vehicle vulnerable to a single "hit."

And, imagine how much more collision damage will cost to repair?

I'm going to rate this one as "cool for car shows, impractical for the real world."


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## rochesterricer (Jan 5, 2011)

I think there is enough energy density for hybrid applications and replacing the standard lead acid battery in ICE cars. Volvo claimed a strut bar bar from this stuff was enough to replace the car battery.


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## Caps18 (Jun 8, 2008)

I'm not seeing it. There are plenty of cars that get dented in fender benders around here, would your car be undrivable then? A bumper is already hundreds of dollars to replace, I wouldn't want to see how much a battery panel would cost.

I understand the desire to keep the interior of the car 'open' and bigger, but I would rather protect the batteries a little.


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## rochesterricer (Jan 5, 2011)

Well keep in mind that factory EVs still come with 12v lead acid batteries to power the accessories, and you use this to replace that battery. You could use it on a part that isn't normally subject to such damage, like the floor or firewall area, since you wouldn't need enough capacity to require that much material.


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## PhantomPholly (Aug 20, 2008)

rochesterricer said:


> Well keep in mind that factory EVs still come with 12v lead acid batteries to power the accessories, and you use this to replace that battery. You could use it on a part that isn't normally subject to such damage, like the floor or firewall area, since you wouldn't need enough capacity to require that much material.


Ok, but if this new material is more like a capacitor than a battery you'd need 300 lbs of body panels to replace the 30 lb lead acid battery.

It's a cool idea, but at this level of capacity I think it's DOA.


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## rochesterricer (Jan 5, 2011)

You're making assumptions about energy density that aren't provided in the article. Based on some statements made, I don't think it is as low as you think it is. For instance:

"In the Volvo S80 they retrofitted with these new panels, Volvo says the power coming from the trunk lid alone could replace all the batteries in the car. A strut brace was even powerful enough to replace the 12-volt battery."


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## PhantomPholly (Aug 20, 2008)

rochesterricer said:


> You're making assumptions about energy density that aren't provided in the article. Based on some statements made, I don't think it is as low as you think it is. For instance:
> 
> "In the Volvo S80 they retrofitted with these new panels, Volvo says the power coming from the trunk lid alone could replace all the batteries in the car. A strut brace was even powerful enough to replace the 12-volt battery."


I didn't think so - the article said:

"The answer was found in the combination of carbon fibers and a polymer resin, creating a very advanced nanomaterial, and structural super capacitors."

Even Supercapacitors are much lower in energy density than lead-acid batteries. 

Unless I missed something, and EEStor started shipping ECUs?


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## rochesterricer (Jan 5, 2011)

So all supercapacitors have the same energy density? I guess that means everything labeled a battery has no greater energy density than the lead acid starter battery in my Civic.


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## PhantomPholly (Aug 20, 2008)

rochesterricer said:


> So all supercapacitors have the same energy density? I guess that means everything labeled a battery has no greater energy density than the lead acid starter battery in my Civic.












Someone got up on the wrong sided of the bed and is being snarky; however, clearly I did not say that.

However, what I did do is allude to the fact that a supercap which even equaled a lead-acid battery would be much bigger news than just "body panels that double as batteries." And you have been around these forums long enough that I would think that would have occurred to you.

Point being, it was entirely appropriate for me to infer that using these as batteries was most likely more of a publicity stunt than a cost-effective solution. If they had really been as energy-dense as batteries, they would have been crowing it to the rooftops.

But perhaps I'm wrong, and EEStor has licensed them its technology for Barium Titinate.


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## rochesterricer (Jan 5, 2011)

Well yes, that is part of why I posted the article. I apologize if that was not clear. 

The reality is that there is no point in arguing until there is more detailed info, if it ever becomes available. To do so would involve nothing but speculation at this point, which is why I posted it in News and not another section like Chit Chat. 

FWIW, the claims in the article require less than an order of magnitude improvement over what is currently available(roughly 10-15 wh/kg for the most energy dense). While definitely very significant, its not nearly as drastic as the claims made by EEStor(over 300 wh/kg if memory serves).

Edit: another thing that makes this debate pointless is the fairly loose definition of the word "supercapacitor."


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## PhantomPholly (Aug 20, 2008)

rochesterricer said:


> Well yes, that is part of why I posted the article. I apologize if that was not clear.
> 
> The reality is that there is no point in arguing until there is more detailed info, if it ever becomes available. To do so would involve nothing but speculation at this point, which is why I posted it in News and not another section like Chit Chat.
> 
> ...


Fair enough, and in truth I was relying on heresay for relative energy density because so many on this forum have stated that SuperCaps would be a horrible way to go (and I do assume at least a few of you are "up on the subject") - so I went and looked it up.

(combination of Wikipedia and a few other sources)
Carbide/Carbon SuperCap - 8.3
Metal Oxide SuperCap - Ruthenium dioxide in combination with H2SO4 electrolyte - 26.7
Lead Acid Battery - 41
Composite (i.e. Carbon / Metal Oxide / CNTs) - 50
Graphene (theoretical) - 77.8
NiMH - 95
LiIon - 100 to 265 Wh/kg

SO, I'm going to assume no one has "tried" Composite SuperCaps in place of floodies, for example, because perhaps they aren't yet commercialized? Or maybe just more expensive?

Well, in any event I agree we need to see some hard specs before I'll start cheering. In the mean time, I'll stick with my original impression that putting the most valuable part of the car on the outside is inviting multiple sorts of Murphy into your life. Aside from wrecks, the same sort of kids who stole hubcaps in my youth will be stealing body panels...


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## rochesterricer (Jan 5, 2011)

Yeah the Lithium Ion based capacitors I've read about are somewhere in the 10-15 wh/kg range. I'm guessing nobody uses these because supercaps are very spendy. Probably drastically more expensive than a pack that uses Chinese prismatics, for maybe 20% of the range. And range is the big thing that people worry about with EVs currently. 

I wouldn't care to put them on the outside either. I would rather use them to build a floor-based battery pack that is strong enough to be a stressed member of the chassis, similar to the Tesla Model S.


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## PhantomPholly (Aug 20, 2008)

rochesterricer said:


> Yeah the Lithium Ion based capacitors I've read about are somewhere in the 10-15 wh/kg range. I'm guessing nobody uses these because supercaps are very spendy. Probably drastically more expensive than a pack that uses Chinese prismatics, for maybe 20% of the range. And range is the big thing that people worry about with EVs currently.
> 
> I wouldn't care to put them on the outside either. I would rather use them to build a floor-based battery pack that is strong enough to be a stressed member of the chassis, similar to the Tesla Model S.


That would work, provided that that pack had an automatic disconnect from the rest of the system in the event of failure. Tesla has shown with the most recent "incident" that isolating the batteries in groups is a good thing...


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