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Hello,

I should soon have a fully-functional 2015 Tesla Model S 85D. At least I think so; there are a couple details to work out yet. In any case, I find it unacceptable that the roof is fixed in place. I've looked at some "convertibilized" Model S attempts but mostly they're pretty bad. So I have been thinking about yanking the drivetrain and putting it into something else more to my liking. I think my first choice would be a Bentley Continental GT Convertible. If that car has characteristics that make it completely unworkable I would consider various other fancy convertibles...perhaps an Audi A5 or BMW of some description. Something on the larger side, as my daily driver is a 911 and I have a Roadster reserved that hopefully will someday be built. So in other words I have small/fast covered...this one is to be the cool boat convertible instead.

I have some experience with EVs, having done a Chevy S-10 way back in the day. But the 9" brushed DC motor, forklift controller and floodies are to Tesla equipment kinda like a biplane is to an F-22, so I consider that knowledge dubiously relevant. I know my way around a car, mechanically speaking...but I'm certainly no engineer.

So, first question: is this just really, really dumb?

Next up, are there any obvious things that just won't work from the Bentley perspective? Are there other options that would be clearly smarter choices? I do note that it's an incredibly heavy car, but it's not clear to me how much of that is the existing drivetrain stuff that will come out. I'd say it's pretty clear it would still end up way heavier than the Model S. I don't require extreme performance or range, but I don't have a great feel for how detrimental that will be. I think I'd be perfectly happy with 150 miles or so of range and could accept as low as maybe half that. I'd like it to be reasonably quick, but it doesn't have to beat its former W12 self or anything.

Since I'll have the whole Model S to work with, can I make it still all work together? I see that most "Tesla powered" conversions are using non-Tesla controllers and/or batteries. Does keeping the controller/touchscreen/batteries/charger together not work like I would expect? If I did that could I charge at superchargers? I assume trying to transplant the autopilot hardware and make that work is out of the question? I would also very much like to be able to keep the dual motors both for the performance advantage and winter traction...to what degree does that seem feasible?

Finally, being a 2015, the (still original) battery pack has somewhat diminished capacity (around 80%) so it's kind of long in the tooth anyway. Is it possible to get it refreshed with new cells? Or should I just be looking at other non-Tesla pack options? Should I consider getting somebody to refurbish/refresh the motors too?

I'm sure I'll have a ton more questions eventually, but for now those are the ones on my mind. Really appreciate any thoughts or advice. Thanks.
 

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Damn, no-one answers on here... A bentley continental is heavy so consider that the miles per charge will be even less with the same amount of batteries. The lighter the better with an EV. It's possible though. I'm thinkign about converting my 335 to electric also, but I'm considering if it's even worth it... Might just sell it as is and try to find a barnyard deal shell.
 

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Just want to say that it will be almost impossible to make it so that the conversion will be able to use superchargers. Tesla doesn't even let vehicles with a rebuilt salvage title use superchargers.
 

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Hello @HLCinCOU,
There's a lot you asked about there. And I'm sure you probably figured this out, but I'm pretty sure gary32's comment, "Sounds perfectly logical to me" was them being sarcastic.
For starters, I have to say that the idea of converting a more modern Bentley to electric with Tesla components sounds super cool to me, and I'd love to see it (and not to sound like too much of a shameless plug, I'd love to be a part of such a project). With that being said, there are many hurdles to what you propose. I'll try to keep it relatively brief and general in this post. First, let's talk about your donor (the Tesla). Yes, there are clearly components you could repurpose from that, most notably the battery modules and the motor(s). In fact, Tesla battery modules (obviously used) are often leading candidates in conversions because they are both affordable (on a $/kWh basis), have some of the highest energy density you can find, and they are a pretty well known and reliable product at this point. As an aside, I've never disassembled the battery modules out of a Tesla, I'm sure there are people on this forum that have and/or plenty of YouTube videos that show it, but I'm pretty sure that in itself is a big job, and I think it is often most effectively done in a "no going back" fashion that is destructive to the rest of the car's structure.
Telsa motors are obviously great feats of engineering and very powerful, but they are not easy to work with because they are very proprietary. There are a couple of folks out there now that have "hacked" and reversed engineered controllers for them (Stealth EV is one I know of, but there are others), but it is very, very unlikely that you're going to "re-use" the donor controller, or for that matter, practically all of the Tesla's electronics. They just don't like life outside of a Tesla. As far as other components that you may be able to use from the Tesla? I'm not sure, as its not where I've done a lot of my EV work, but people have used the heater, the charger, and some other misc components from Teslas. I think it would be a hodge-podge of what you'd be able to reuse, but I doubt you could count on reusing much beyond the batteries and motors. Oh, and I've yet to see anyone reuse a Tesla's charging components to the point of then being able use Telsa's charging infrastructure (i.e. use a SuperCharger to re-charge). It is probably out there, but that just seems like a very difficult challenge to me. So, you'd most likely be talking about using a more "traditional" EV charger with a J1772 interface (which conversions do all the time).
I'm not sure, but there's a good chance that you could just sell your Tesla, and then go to some of the various suppliers of "salvage" Tesla components for the same batteries, motors, etc. that you'd be pulling out of your donor car and still have some $$ left over. Again, not sure, but I'd recommend doing that calculation before actually taking your car apart.
As for the car you're thinking of doing the conversion on, I'll say it up front, I've never driven or turned a wrench on a Bentley, so I'm far from an expert on them; but basic physics gives some pretty clear calculations on how difficult it is to move an object through the wind the heavier it gets. Not to get too geeky here, but the formula for aerodynamic drag is exponential (not linear) as speed increases and also involves weight as a proportional figure. (That's why the caveat of "in a vacuum" is always given in Physics 101 when learning that the acceleration of gravity is the same on all objects regardless of mass.) And of course Newton's 2nd law (it might be his first, I forget) is F=ma, or solved for acceleration: a=F/m. In other words, as your mass goes up, you're going to need a proportional amount of force (or with a car, torque), to have the same amount of acceleration. Sorry for the diversion there, but the point is, performing an electric conversion on a "heavy" car, especially one that might be particularly heavy, is just a very difficult proposition from the get go.
Also keep in mind that the more modern a car is, the more "integrated" all of its components (i.e. electronics) are, and thus the more difficult a conversion becomes. And by "modern", anything within about the last 20 years or so easily falls into that category with everything being on CAN buses and that sort of thing.
Mind you, I'm not saying it cannot be done, like I said at the start, I'm sure it could, and if done right, it would be awesome, but just know that on Bentley Continental GT Convertible it would be very, very complex and involved (much more so than probably 99% of the conversions you're going to see people on here doing), and of course that also means it likely be very expensive.
You had asked if not the Continental, then maybe what? Given given everyone's personal tastes, that seems like a nearly impossible ask. Seems like you were wanting to go more of a grand touring convertible route. You also seem to have a taste for high-end European cars. So first question, are you okay with something "classic", say not any newer than 25 years or so? For all of the reasons I was mentioning, that will just make it a lot more feasible. Anything from an Mercedes Benz SL linage holds a lot of promise (there's even a company out of the UK doing these). How do you feel about classic Jags? Of course there is a cross-over point with classic GTs, such as the "classic" Aston Martins, where tearing the ICE (internal combustion engine) out of them becomes a sin.
Hope all of that rambling helps! C.J.
 

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I see that most "Tesla powered" conversions are using non-Tesla controllers and/or batteries.
Usually they seem to use either the original Tesla inverter with a replacement controller (logic) component, or the entire original Tesla controller/inverter with an external controller to manipulate message so the controller gets what it needs to function without the rest of the car.
 

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Finally, being a 2015, the (still original) battery pack has somewhat diminished capacity (around 80%) so it's kind of long in the tooth anyway. Is it possible to get it refreshed with new cells?
No. Tesla doesn't believe in repair, in general. As with other manufacturers, the battery modules can be replaced, but are never disassembled for repair. In the Tesla modules specifically, the cells are all stuck together with an adhesive and connected in a way that would make it impossible to replace a single cell.

Should I consider getting somebody to refurbish/refresh the motors too?
I don't know what would ever need to be refreshed or refurbished. In theory it might be able to replace a worn-out bearing, but by the time one of these motors needs anything repaired it's likely time to recycle the materials rather than fix it.
 
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