Shocking dream! [MX5-ophiles look away now!]

[R5]

Hello.


Recently I read a story of a guy who made an electric S2000, that got me thinking. I decided to do some research on my thought, an electric MX5, and discovered a one with no engine for £700, I then looked into batteries and motors and the best I could fine are used by Tesla, in the Model S, but they'll be too expensive.

I'm wanting to know the answers to the following
• which would be more cost efficient, hydrogen fuel cell or traditional batteries?
• will the MX5 fit a large battery pack?
• will I need to buy a single-speed CVT?
• what other modifications will I need to make?
• are there any other motor/battery combinations that you would recommend which are powerful and efficient?

 

[Joey D]

Here's a good starting point:

http://www.evmiata.com/

 

[R5]

Here's a good starting point:

http://www.evmiata.com/

It's been done? Wow. I'm way behind....

 

[Joey D]

You still shouldn't be put off from doing it, it would just make it easier to accomplish. An electric Miata with a good suspension on it would be a blast to drive. Just think of the torque.

 

[R5]

You still shouldn't be put off from doing it, it would just make it easier to accomplish. An electric Miata with a good suspension on it would be a blast to drive. Just think of the torque.

Yep, all those torques

 

[homeforsummer]

which would be more cost efficient, hydrogen fuel cell or traditional batteries?

Batteries, by a long way. I'm not sure if any company even commercially makes a suitable, kit fuel cell for use in cars.

will the MX5 fit a large battery pack?

It depends how you define "large". A Miata is a physically small vehicle and there's a limit to how much stuff you can cram into it.

• will I need to buy a single-speed CVT?

No. For sake of clarification, no current electric car uses a CVT in the traditional sense. While electric vehicles are often described as having a "single-speed transmission", not all single-speed transmissions are CVTs.

Most electric cars use what's commonly called a "reduction gear" transmission. This turns a high-rpm motor into a more usable lower-rpm output at the wheels.

I suspect off-the-shelf reduction gears are available, but most home-brew EV conversions tend to just use the car's regular gearbox locked in something like third or fourth gear, which effectively does the same job. Some even let you shift gears, though it's not as important with an electric motor.

This is also a bit of a hack of course, and means you need to retain heavy components like the gearbox and propshaft. The ideal solution would be to hook an electric motor straight to the rear diff somehow, but I've no idea how much re-engineering this would require - almost certainly quite a lot.

what other modifications will I need to make?

Surprisingly few, to my knowledge. You'd essentially be able to remove anything normally associated with the combustion engine, which means tearing out a lot of stuff, but then much of that space would need to be filed with batteries in order to provide a decent range.

But generally, electric vehicles are incredibly simple. I suspect the largest engineering hurdle would be designing suitable cradles for the motor and batteries to sit in at whichever end of the car you install them in.

are there any other motor/battery combinations that you would recommend which are powerful and efficient?

This is probably a question best posed to dedicated EV forums.

 

[R5]

Thanks, homeforsummer

 

[LeadFootLiam]

Cool! If you end up committing to this I wish you the best. I have seen an electric MX5 before.

 

[Eunos_Cosmo]

I seriously doubt a stock Miata gearbox could handle a powerful electric motor.

 

[homeforsummer]

I seriously doubt a stock Miata gearbox could handle a powerful electric motor.

Depends how powerful you mean by powerful. A stock Miata gearbox can handle turbo conversions with a healthy dollop of torque that isn't normally there, so as long as someone didn't go crazy with the electric motor (i.e. you wanted like-for-like performance, rather than an electric dragster) it would probably be fine.

Also, my knowledge of the mechanics of it is limited, but you're less likely to put shock through the drivetrain with an electric motor than you are with even a standard engine. No gearchanges to bang through, and linear power from the word go when you floor it (rather than building up loads of revs and then dumping the clutch).