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Discussion Starter · #1 ·
My project is a light reverse trike and I have owned one with a 2008 'busa engine that was around 172HP. For a 700 lb trike that is almost enough power :) A Warp 11 motor make 114 ft/lbs of torque at 1440 rpms (44 hp) drawing 1280 amps. I am mostly interested in extreme power , not so much with range. 30 to 50 miles would be great. I was thinking with a 2:1 direct drive that is 244 ft/ls available any time, and the HP numbers are not really that low if the motor is at 6000 rpms. Would the torque be the same at 6000 rpms? If yes tha is 329 HP but i think a dc motor loses torque as revs increase, to a point,

Is that too much motor, would a Warp 9 be better?

I am totally lost on how to choose the right battery voltage and discharge rate. I am assuming that the battery must be capable of delivering 1280 amps at least. Is that not the real determining factor on performance? How many amp hours would I need for 30 miles and four or five bursts of 10 seconds of full throttle?

I hope I have asked this question intelligently. I would like to know how to calculate the battery requirements for future conversion projects too. Would you buy an electric, tilting trike that looks something like a T-Rex Aero if the price could be kept around 35K? I wanted it at 25K but have no clear idea of the battery costs.
 

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Discussion Starter · #3 ·
I have a good bit of experience with RC brushless motors, can I assume a car DC motor also has a kv rating? I also know it's absolutely critical to choose the right kv motor for efficiency. What I don't know and had not considered was the best rpm range, and 60 mph seems a very good speed for max effciency. I may change that to 50 mph as I would tend to drive on surface streets rather than the highway. Plus highway speeds where I live tend to average 80mph. If max speed is important I have never gone above 150 mph, even in my twin turbo viper (just 800 rwhp). I doubt I would even attempt 150 in a roller skate with a motor like a T-Rex.
I listed the gas trikes specs so I could find out what is necessary to achieve similar performance, and I always expected the weight to increase. What is more important for EV performance, total voltage or cell discharge rating? I expect that delivering the necessary amperage for a given rpm is the limiting factor, and doing it with the lowest weight is the goal.
Am I ontrack here, or should I be more concerned with kwH ? Its easy to convert HP to kwH, but with an electric motor I think you would need to integrate over the torque curve for a real comparison of engine vs electric motor. Are there any links to the math needed for a true compare?
 

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Discussion Starter · #7 ·
Thank you so much for the in depth answers. I obviously need to study non permanent magnet brushed dc motors. Power is applied so differently than an ICE I'm finding it hard to choose batteries and a motor, and an AC motor just makes it worse. I'm looking through the builds posts trying to find something similar.
 

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Discussion Starter · #10 ·
Making a few assumptions I may be way off base here, but I'm guessing that salvaged batteries cells have a low discharge rating. I know RC pack costs go way up for higher discharge rates, and that you can use a higher C rated pack with a suitable motor for more performance but with reduced range (mh) for a given battery weigh. I also know using new high C cells would be very expensive, so it kinda seems the choice is a cheaper salvage pack or a custom expensive (maybe very) pack. To get the results I want option 2 seems like the way to go, and if necessary add more range later with additional packs as funds allow or we get some new tech with better energy density. I think what I'm looking for are some real world number (like 15kwh) so I can calculate what the costs are.

For a given weight there has to be a way to compare an electric and ICE powertrain performace. I thiunk most people would understand 0-60, 60-100, 0-100, etc much better than HP, torque, etc. comparisons. I would really like to see comparisons from 30-60 and 30 to 100 mph to help eliminate traction issues (wheelspin). Can these be calculated from torque curves and drive ratios, and are there tools to do that?

I am still really lost on what I need. Can someone just suggest a motor / battery / controller setup that would work. Maybe I nned to look at the EV T-rex and try to find one for a test drive so I have an idea of what I'm comparing. I have never run either the trike or my viper at the dragstrip, but seat of the pants feel the trike accelerated harder.
 
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