Question about E-motors - Page 2 - Fuel Economy, Hypermiling, EcoModding News and Forum

Christ · 10-18-2009, 08:40 PM

That link above is the only two options I'm looking at. They're compact compressor motors, but without a controller, I just assumed they'd only draw enough amps to make 5 HP at whatever voltage. Less than 5kW, in other words, regardless of voltage. Of course, if it won't take DC voltage, I guess I'd have to use a DC/AC inverter, which would probably put the whole thing out of reach in terms of what I was thinking about.

Bicycle Bob · 10-18-2009, 09:31 PM

Even the link clearly says "Generic Error."

Christ · 10-18-2009, 09:45 PM

Did you actually look at the link, or are you making conjecture about the data gathered for the automatic parse feature?

Bicycle Bob · 10-18-2009, 09:54 PM

I'm reading what it says on page one where you give the link, at least as it appears in Canada. Clicking on the link gets the same.

Christ · 10-18-2009, 09:55 PM

Must be cuz I have it cached, then. I fixed it.

orange4boy · 10-18-2009, 11:38 PM

Sorry to be a party pooper but an induction motor would require an expensive controller and high power inverter.

A given motor will put out roughly double the hp and rpm with double the voltage. They like to run at a certain rpm and will put out many more hp to get there if loaded up. You can "safely" double the voltage/HP of a motor but have to watch out not to overheat it and probably not run it continuously at double It's rating . I use a $10 digital oven thermometer to keep tabs on my bikes.

For an easy contactor motor EV set up I would look for a used permanent magnet brushed motor. Can be found cheap if you know where to look. Old forkifts, etc. Look for H rated motors (can be run the hottest: low-A, B, F, H-high)

Brushed PMDC is 2 wires, no waiting. Fairly simple to set up a series parallel contactor arrangement. That's how the Auranthetic bikes are set up. They are rated 1 hp cont. but probably put out 3 or more up hills.

Christ · 10-18-2009, 11:55 PM

Quote:

Originally Posted by orange4boy

A given motor will put out roughly double the hp with double the voltage.

As was stated above, an induction motor would require an expensive controller and high power inverter.

For an easy contactor motor EV set up I would look for a used permanent magnet brushed motor.

2 wires, no waiting. Fairly simple to set up a series parallel contactor arrangement. That's how the Auranthetic bikes are set up. They are rated 1 hp cont. but probably put out 3 or more up hills.

Yeah, I've grasped that, but I really only want to run it at 120VDC, so it should only be able to make ~5HP at any time, right?

The only real variable there should be the amp draw, which (obviously) changes the resultant output.

*The basic idea in more depth - gear the motor so that at max RPM, it propels the vehicle at 30 MPH with only one multiplication of torque (no gear changes) (3450RPM for those two motors).
*Use a contactor setup controlled by a pedal to switch the motor on/off with no PWM. Either motor on accelerating/max speed, or motor off/no speed.
*Only needs a range of a few miles to get me around town and home... anything else would require 40+ mile range at the least, and isn't feasible for me at this time.

If the "snap" is too much, I could add a torque damper between the motor and drive to absorb some of it... clutch plates have springs in them for exactly this reason, I could make something similar without too much trouble.

So basically, let's take the motor out of the equation, and work with the fairly simple parameters laid out above.

Given those parameters, could Joe next door take a 5HP compressor motor, slap it into his car, stack/wire 120V worth of batteries in the back seat, and drive to the parts store to buy the parts to fix an engine (that probably came out of the same car...)? (Assume that whatever E-motor Joe is using happens to be OK with DC, even though it's an AC motor.)

orange4boy · 10-19-2009, 03:52 AM

Quote:

Given those parameters, could Joe next door take a 5HP compressor motor, slap it into his car, stack/wire 120V worth of batteries in the back seat, and drive to the parts store to buy the parts to fix an engine (that probably came out of the same car...)? (Assume that whatever E-motor Joe is using happens to be OK with DC, even though it's an AC motor.)

Yes, that could all work. You would not get much whip in a car from 5 hp but the motor would pull a lot of amps.

If the car only needs 5 hp to get up to speed. Might be a little under powered. Depends on the car, terrain, etc. Is it flat where you are?

ASV · 10-27-2009, 11:11 PM

use the 5H to buld up a little tork in a flywheel and use a clutch

Christ · 10-27-2009, 11:14 PM

Quote:

Originally Posted by orange4boy

Yes, that could all work. You would not get much whip in a car from 5 hp but the motor would pull a lot of amps.

If the car only needs 5 hp to get up to speed. Might be a little under powered. Depends on the car, terrain, etc. Is it flat where you are?

Well, here around town, yes. The vehicle would never see any steep hills, only gently rolling roads.

I'd like to reiterate that we're literally talking about a car that weighs in right around 1,000 lbs, as well. It only takes like 25 or so HP to do 60 in my 3500# Minivan, with Cd .3 and A of 33 ish M. I just can't imagine that it would take more than about 5 HP to go around town at 25-30 MPH in a sub-1/2 ton car with frontal area of about half of the Minivan.