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A few pictures of my electric Midget conversion project

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jbman Avatar
jbman Silver Member Jefferson Black
Colorado Springs, CO, USA   USA
Ah, yeah, I saw that site just a few weeks ago, actually. Gorgeous cars, though I'm dubious of their claims of affordability, and I wonder if the performance is there? I just can't imagine a really good electric conversion of a nicely restored classic being anywhere near affordable.

In reply to # 3710439 by Gavin207 Great idea, looks good. Don't know if you've seen it, but there's a chap in London who has built an electric Morris Minor, so same drive train - http://londonelectriccars.com/ . He kept the gearbox, and only uses 2nd and 4th.

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BMac Avatar
BMac Brendan MacRae
Grass Valley, CA, USA   USA
Fascinating build.

I normally lurk in the Sprite forums but come over here occasionally to check things out.

I want to ask about torque. We hear about the incredible amounts of torque from electric motors. Will the drive shaft & U-Joints, diff and rear axels on your Midget handle the torque from this motor?

Also, reversing - just a switch?

jbman Avatar
jbman Silver Member Jefferson Black
Colorado Springs, CO, USA   USA
My motor puts out on the order of 300 ft lbs of torque with an extremely flat curve. So, off the line, I have full power available to me. I am using direct drive and ditched the transmission since I don't need the torque multiplication, so it's just 300 ft lbs straight to the diff. Nothing has broken, yet, but I'm building some traction bars to offset some pretty extreme axle wrap.

Reversing is done with a reversing contactor, which is a couple of super heavy duty relays linked together. My motor is a series wound DC motor, so the current flows into the field coils, then into the armature coils, and then back to the battery. Reversing the connection of either the field or the armature will cause the motor to spin in the opposite direction. The reversing contactor facilitates the connections internally, while ensuring that it is impossible to short the connections. Both contactors on = open, both off = open, one on one off is forward, one off one on is reverse. I just have it wired up to a DPDT switch for 12v to the coils. Up is forward, down is reverse. No shifting or anything.

The car is incredibly easy to drive, other than dodging pot holes while I wait to replace the flat front shocks...

EDIT: For clarification, the amperage determines the torque. I can hit it with 300 ft lbs at “idle” with WOT at 1000 amps, but I rarely go over 50-100 amps from a stop.

In reply to # 3710999 by BMac Fascinating build.

I normally lurk in the Sprite forums but come over here occasionally to check things out.

I want to ask about torque. We hear about the incredible amounts of torque from electric motors. Will the drive shaft & U-Joints, diff and rear axels on your Midget handle the torque from this motor?

Also, reversing - just a switch?



Edited 2 time(s). Last edit at 2018-04-05 10:15 AM by jbman.

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refisk Avatar
refisk Rick Fisk
Frankenmuth, MI, USA   USA
So Jefferson, that means your car will go 100 mph in reverse - right? grinning smiley

Some microcars with 2 stroke engines were set up the same way. When you needed to back up you came to a stop, turned off the engine, flipped a switch, and restarted the engine which was now running in the opposite direction so you could back up.

In reply to # 3711012 by jbman My motor puts out on the order of 300 ft lbs of torque with an extremely flat curve. So, off the line, I have full power available to me. I am using direct drive and ditched the transmission since I don't need the torque multiplication, so it's just 300 ft lbs straight to the diff. Nothing has broken, yet, but I'm building some traction bars to offset some pretty extreme axle wrap.

Reversing is done with a reversing contactor, which is a couple of super heavy duty relays linked together. My motor is a series wound DC motor, so the current flows into the field coils, then into the armature coils, and then back to the battery. Reversing the connection of either the field or the armature will cause the motor to spin in the opposite direction. The reversing contactor facilitates the connections internally, while ensuring that it is impossible to short the connections. Both contactors on = open, both off = open, one on one off is forward, one off one on is reverse. I just have it wired up to a DPDT switch for 12v to the coils. Up is forward, down is reverse. No shifting or anything.

The car is incredibly easy to drive, other than dodging pot holes while I wait to replace the flat front shocks...

EDIT: For clarification, the amperage determines the torque. I can hit it with 300 ft lbs at “idle” with WOT at 1000 amps, but I rarely go over 50-100 amps from a stop.

In reply to # 3710999 by BMac Fascinating build.

I normally lurk in the Sprite forums but come over here occasionally to check things out.

I want to ask about torque. We hear about the incredible amounts of torque from electric motors. Will the drive shaft & U-Joints, diff and rear axels on your Midget handle the torque from this motor?

Also, reversing - just a switch?

Havenor Avatar
Havenor Richard Costa
Fairhaven, MA, USA   USA
That motor has to be a beast. The HP has to be double, triple, the MG engine?

jbman Avatar
jbman Silver Member Jefferson Black
Colorado Springs, CO, USA   USA
In short... yes smiling smiley it took a second to get used to, and I burned out a couple of times in reverse! Some people have the reverse switch add a resistor to the throttle wire to reduce the input. Most throttles are 0-5k or 0-5v, so adding a resistor dramatically reduces the throttle signal to make things feel more natural. I might do that some day.

In reply to # 3711025 by refisk So Jefferson, that means your car will go 100 mph in reverse - right? grinning smiley

Some microcars with 2 stroke engines were set up the same way. When you needed to back up you came to a stop, turned off the engine, flipped a switch, and restarted the engine which was now running in the opposite direction so you could back up.

BMac Avatar
BMac Brendan MacRae
Grass Valley, CA, USA   USA
Wow - well, 300 ft pounds is less than torque than I expected but still huge compared to the 75 foot pounds from the standard high compression version of the 65hp 1275cc engine from the factory (although this car I guess had the 1500 - similar specs I would assume - but slightly more torque).

No wonder the rear end is getting twisty! I think traction bars would is a good idea.

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jbman Avatar
jbman Silver Member Jefferson Black
Colorado Springs, CO, USA   USA
You can really go ham with these builds. Mine is very mild compared to what's possible. Add bigger motors, more amps, etc, and things get really ridiculous. This guy's car is old, now, but he was at nearly 800 ft lbs of torque: White Zombie. The new Tesla Roadster is capable of 7376 ft lbs of torque. That just boggles my mind.

In reply to # 3711036 by BMac Wow - well, 300 ft pounds is less than torque than I expected but still huge compared to the 75 foot pounds from the standard high compression version of the 65hp 1275cc engine from the factory (although this car I guess had the 1500 - similar specs I would assume - but slightly more torque).

No wonder the rear end is getting twisty! I think traction bars would is a good idea.

jbman Avatar
jbman Silver Member Jefferson Black
Colorado Springs, CO, USA   USA
I put the top up and finally took some pictures of the essentially complete car. Still needs a cleaning and vacuuming and such, but it turned out pretty nice, given what I started with! I'm not happy with the speedometer, but it will do for now.

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jbman Avatar
jbman Silver Member Jefferson Black
Colorado Springs, CO, USA   USA
Closer to quadruple, assuming about 65 horsepower for a 1500 smiling smiley I have everything set up for a peak of 196 volts and 1000 amps. That's 196Kw, which converts to 262.84HP. The motor is only about 89% efficient, though, so it ends up being about 233.92HP. It is very zippy, and lots of fun! The torque curve is what makes it more fun than you might think, though, since you've got nearly full torque from a complete stop.

In reply to # 3711030 by Havenor That motor has to be a beast. The HP has to be double, triple, the MG engine?

1974MGMidget Avatar
1974MGMidget Silver Member Jack Orkin
Grayson, GA, USA   USA
What is that - 200 MPH on the speedo?! cool smiley

jbman Avatar
jbman Silver Member Jefferson Black
Colorado Springs, CO, USA   USA
I see a Midget land speed record in my future!

In reply to # 3712102 by 1974MGMidget What is that - 200 MPH on the speedo?! cool smiley

Kerr Avatar
Kerr Platinum Member Norm Kerr
Ann Arbor, MI, USA   USA
I hope that you will keep the exterior just as it is, oxidized paint, '70s decals and flat, faded bumpers, but with fully restored suspension, nice interior and fantastic drivetrain. Should be quite a surprise to other motorists as you zoom on by!

nonracer Gold Member Steve Codianni
AZ, USA   USA
Great build Jefferson , sounds like a fun car to drive . I would be cautious about a traction device , while I’m sure its needed to control axle wrap it will most likely be the end of your axles and differential if you completely eliminate tire spin. This is the same situations we faced when building our drag cars , once we were able to get the car to “ hook up “ we found the weak links . You can experiment with spring bias by putting an extra leaf or 2 in just the front half of the spring pack , this can help the spring from flexing too much . A traction bar with a rubber snubber or “ slapped bar “ might be good also since you can adjust the gap where it makes contact with the spring eye . I would think with a little tire spin you won’t break anything. Just my .02

GeorgeOhr Nonya Business
Yes, confused, USA   USA
Don't know if it's been asked yet but how much do you have in the conversion?

Thanks.

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