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Old 09-28-2014, 12:42 AM   #25 (permalink)
Master EcoModder
Join Date: Sep 2010
Location: Saskatoon, canada
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ChargE (not yet running) - '92 Mazda MX6 LX
90 day: 33.89 mpg (US)

Ford Prefect - '18 Ford F150 XLT XTR
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Originally Posted by freebeard View Post
Has anyone posted a comparison of shifting and just leaving it in top gear? I was thinking that torque gets you off the line and horsepower limits the top speed.
I have not seen one. I would be interested as well.

Talking it through, I would expect the acceleration to be a bit less unless your motor and controller are over-sized .. and your transmission/axles/etc can handle the boosted torque.

The siemens motor on the single-speed borg-warner transmission for the Ford Etransit is rated over 100 kw. The motor used by the Coda is(I guess WAS) also over 100 kw, using a different gear ratio on the same borg-warner gearbox.

The original beetle was no speed demon, but it got by with under 60 hp (45 kw or so)

The reason I ask is I'm following and wonder about the downside of a single-speed, clutchless, electric reverse drivetrain.
I am no expert. My opinion is that the downside is a bigger controller and a bigger motor to get good performance. My standard transmission weighs under 75 lbs. I hope that the MGR gives decent acceleration. I hope to use it in a WIKISPEED car. I hope it gets GREAT performance on a 1400 lb car

Since Toyota designed the motor, gearbox and axles I would expect them to be well matched, with decent safety factors. My clutch is a mechanical fuse for my system. I can turn up the torque until I smell clutch. The MGR should not need anything so crude.

I need to educate myself about contactors. I noticed in Paul Holmes VW conversion he had a lanyard to pull on a shorted plug. But thread like have it in the trunk. Better to have it accessible from the driver's position?
The contactor opens when 12V is no longer applied. It can be wherever you like. If you have a pull switch or cable, you have fewer options on where it can go since the cable must be routed.

I have two contactors, one for the precharge and one for the main enable. That gives me minimal redundancy. I need to figure out a visual indication that both contactors open each time.

In the case that the contactors BOTH fail AND the controller fails ON to full throttle, there will also be a cable connected to a DC breaker under the hood. Similar in function to the shorted plug you discuss. Pull the cable (I hope it looks like an old style choke) and the breaker (like the breaker in your house panel, but BIGGER and it can open on 500A of DC) the controller loses power. That should be paranoid enough for most people.

And lastly, if all else fails, I press the clutch and let the motor overspeed until it tears itself apart .. but it stops and I don't die. Perhaps I am hurt by the motor shrapnel, likely not. The warp11 is big and sturdy.

Watch out .. reading posts by paranoid people may be hazardous to your health .. paranoia is catching!
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