AC Conversion Suggestions

Hi guys, I’ve been toying with the idea of doing a conversion now that I’m no longer a student. Seems fun. I don’t know squat (or is that a double negative?) about how AC motors work or which ones I should be considering. All I know is a little math regarding figuring out voltage and power for a particular battery arrangement. Anyway, I was hoping for input on the following subjects.

  1. Would any of thesemotors work, and why not/yes? I was looking at any of the 125 hp models just because that’s about a honda civic, but it weighs 1400 lbs, which seems huge. What should one be looking for in an AC motor other than a given amount of hp and torque? Seems like one can always just adjust the battery setup to achieve desired voltage for a particular motor.

Also, does the following make sense? Suppose I went with a 100hp motor which according to their specifications draws 230 amps @ 230 V (coincidence it’s the same, not a typo). In my world, Power = Voltage * Current = 52,900 W ~ 53 kW. However, 53kW ~ 70hp, so how the heck are they listing a 100hp motor taking only 230 amps @ 230V. What gives?

  1. What else is necessary? It seems like for a DC setup you need a controller (do you manually program this based on your motor / battery / weight combo?), an adapter plate, and some batteries. That’s for a DC setup, so do you need anything to convert DC -> AC, or does the controller do this too? Am I missing parts?

  2. How can I figure out range for the car? I have no idea how to translate going 1 mile into taking up a certain amount of stored energy - I don’t know how much drag / friction attenuate momentum as a function of speed. My high-school physics isn’t helping me out here :slight_smile:

Thanks in advance.

I’m in the same boat. About the only thing I’ve been able to glean from it is the higher the voltage the faster it can go, and 1 electric HP = 3 ICE HP. So, you need an electric motor with roughly 1/3 the HP of the ICE you replace. But it doesn’t all make sense, for example there’s a fellow that used a 36V forklift motor in an S10 that goes 180MPH through the quarter mile in just over 9 seconds. No idea on its range, but he built it to be street legal. I’ve not been able to get much technical information here, either the folks here don’t know the details, or don’t want to commit information, or I’m not asking the right questions or I’m not understanding what responses I do get.

For my own truck, been exploring using a Warp 11 or maybe a Warp 13 motor. The Warp 13 is larger and more expensive, but draws less electricity for the power it puts to the ground, seems to be more efficient. Another option would be the same AC traction motor the BMW conversion below uses.

Perhaps these links will help:

S10 dragster
BMW conversion
List of converted cars with a rundown of what they used, and sometimes results

1 HP electric =1 HP ICE. The difference is in torque and HP curves. A 200HP ICE produces 200HP at very high rpm, this is generally peak HP for autos. A 200 HP electric motor produces much more torque over a broad range of RPM’s which translates into a much flatter HP curve over the RPM range. So your honda civic that honda claims makes I dunno maybe 150 HP from the factory, probably makes around 50-75 HP in the RPM range that most of us would drive it. Google torque curve and you will find lots of info to explain this idea better than I can.

As far as the current and voltage of a split phase or 3 phase AC motor not adding up to the proper KW or HP, you are not calculating correctly. First off the current rating on the nameplate may be max current. Secondly the formula for KW of 3 phase AC power is KW=volts x amps x 1.73 x PF. 1.73 is the square root of 3, which accounts for the 3 phases each carrying part of the load. PF or power factor is the relationship between real power, reactive power and apparent power.

I’m no teacher so I recommend using wikipedia or google to find some further reading if you do not have a firm grasp on these concepts.

I kept wondering why people were putting small 10-15hp electric motors in vehicles to replace gas engines. I read finally that gas (ICE) engines are rated in peak hp, as above stated where an electric motor is rated in continuous HP.

They went on to say that an electric motor is equivalent to a gas engine 8-10 times larger. So a 10HP electric may equate to 80-100hp gas.

So IF you can fit that 125HP under the hood w/o it dragging the ground and can find the batteries to handle it, you’d be looking at 1000-1250 HP equivalent in a gasser and
you’d have a Rocket Ride!!!

Post the photo’s of the first burnouts!:smiley: