[Random9]

Hello everyone!
I have just recently stumbled into the world of DIY EVs and would love to try to make one. I am currently in school to become an electrical engineer but would still definitely consider myself a beginner. I am hoping to create an electric RX-7 that is able to use the supercharger network.

My questions are as follows:

Can I buy a Model S battery pack? Does that include a BMS that would allow me to use the supercharger network?

If it does not include a BMS, are there any aftermarket options that would allow me to use the supercharger network?

Is it the BMS or the controller that effects supercharging?

How much machining is needed to fit motors? I see adapter plates are available for rx-7 builds. Are those all I need to secure the motor in place? I plan to pay a mechanic to remove the engine and want to mess with mechanical things as little as possible as I believe anything that I create will be far worse than a commercial product.


I hope that my questions aren't too stupid. Thanks!

 

[Kevin Sharpe]

I hope that my questions aren't too stupid. Thanks!

They're not at all Can I suggest you start by reading Damien's latest build thread (here) and then watch some of his videos? This will answer many of your questions

are there any aftermarket options that would allow me to use the supercharger network?

With regards to using the Supercharger network, that would involve stealing electricity and I have no doubt that Tesla would come after you. This has been discussed a little on DIY Electric (here).

On a more positive note, several people are developing solutions that would allow you to use the CHAdeMO and CCS rapid charging networks with your DIY EV

 

[brian_]

With regards to using the Supercharger network, that would involve stealing electricity and I have no doubt that Tesla would come after you. This has been discussed a little on DIY Electric (here).

Not all Tesla cars have come with pre-paid Supercharger privileges (the Model 3 does not), and even those that do have limits - a 400 kWh/year allowance. That means that even some owners of stock Teslas have to pay at Superchargers, in at least some circumstances; the current North American price is $0.20/kWh (way over the usual value of retail electricity), and there is a time element as well. An ideal solution would be to enable the owner of a car built with Tesla components to purchase energy at Supercharger stations.

As noted in the linked discussion, Tesla Motors would need to agree. Personally, I think that whatever bull they spout about wanting cooperation with other manufacturers, they know that Tesla owners will be upset if Superchargers get busy with other cars, so they won't want to do this. I also doubt that Tesla Motors would be enthused about DIY projects using salvaged Tesla parts even being on the road, let alone hooking up to high-power charging stations. But hey, those are just my guesses.

The obvious technical solution is to use so much of the original Tesla car that you are essentially just charging the Tesla, which is being carried on a new platform. The problem there is that Tesla has been scrapped, and presumably is no longer entitled to use the Supercharger (with and allowance or by paying)... and the Supercharger system should know that. Any attempt to fool it is clearly not appropriate.

 

[brian_]

How much machining is needed to fit motors? I see adapter plates are available for rx-7 builds. Are those all I need to secure the motor in place?

Most very old motors which are salvaged (such as brushed DC motors from forklifts) and most motors which are sold new for amateur EV conversions are mounted by an industry-standard pattern of holes on the end face of the motor around the output shaft. The commercially available motor adapter plates are built (usually of cast aluminum) to mount the motor on side and to fit a specific transmission on the other side; search this forum for something like "motor adapter" for discussions.

The adapter is only part of the motor-mounting challenge. These same motors tend to come with a shaft which is plain other than a keyway. A manual transmission normally has a splined input shaft, which is designed to be inserted into the hub of the driven disk of a clutch. You need something to connect the two, which is normally referred to in these discussions as a "coupler" (so search for that term), and often incorporates use of the flywheel and clutch which normally go with the transmission. Like the adapters, these are commercially available to some extent.

Finally, you need support for the motor to the structure of the car. Most people build their own mounting brackets, often going to the same point on the car's structure as originally used to support the engine.


If you use a motor from a modern EV, it will not mount the same way as a generic salvage or conversion motor, and will not have a plain shaft. More custom design and fabrication is required... or you can use the motor complete with the transaxle (transmission and differential) that it is used with in the original EV. With the increase in availability of production EVs and components from salvage companies, there seems to be a trend to using these motors (with transmissions, and in addition to batteries) instead of parts sold for conversion. In this case, the mounting issue is with supporting the motor and transaxle (often called a drive unit), and building axle shafts which fit the car on one end and the transaxle on the other.

In an RX-7, using a complete production drive unit would mean mounting it at the rear axle, instead of mounting an electric motor in the original engine space.

 

[brian_]

I am hoping to create an electric RX-7...

Just curious... what generation of RX-7?

 

[brian_]

Can I buy a Model S battery pack?

You can buy a complete Tesla battery, or the modules which are in it. In either case, they will be used parts, salvaged from failed or crashed cars.

 

[Kevin Sharpe]

As noted in the linked discussion, Tesla Motors would need to agree. Personally, I think that whatever bull they spout about wanting cooperation with other manufacturers, they know that Tesla owners will be upset if Superchargers get busy with other cars, so they won't want to do this. I also doubt that Tesla Motors would be enthused about DIY projects using salvaged Tesla parts even being on the road, let alone hooking up to high-power charging stations. But hey, those are just my guesses.

We may find out what Tesla think in the near future...

http://www.diyelectriccar.com/forums/showpost.php?p=958442&postcount=31

 

[brian_]

We may find out what Tesla think in the near future...

http://www.diyelectriccar.com/forums/showpost.php?p=958442&postcount=31

While linked post is about a somewhat different scenario (a non-Tesla charging station providing a Tesla-style connection, presumably to serve owners of Tesla cars... not a non-Tesla-standard vehicle using a Supercharger) it does highlight Tesla's concerns when some part of the system (of charger and vehicle) is not one of their own approved designs.