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Old 09-02-2012, 05:52 PM   #40 (permalink)
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I've decided to use a smaller accessory motor to power my A/C unit in my 2001 Civic EV. I can't use the second shaft on my motor and I don't want to deal with an electric A/C compressor so this is going to be an experiment.

So the past two days my dad and I have been building the mounts for the stock Civic EX A/C compressor and the motor I am using, a treadmill motor I got years ago for $20. The specs are: 2.5 HP peak @130 volts, 1.5 HP cont @ 95 volts, 18.5 AMPs and 6750 RPM.

After doing some research on this motor I decided that 36 volts would be a good base start, which seems to be about 2500 RPMs at the treadmill motor unloaded (just on A/C pulley, clutch disengaged). I hooked up my current shunt to the (+) line and proceeded to test as there is no data on the actual power requirements on the Honda Civic A/C compressor.

Test 1:
Pulley on the treadmill motor: 3" diameter
Pulley on the A/C compressor: 4.5" diameter (stock)

Voltage: 36 volts
Current: 25 AMPs

The A/C was blowing cold in about 15 seconds and it gave me two very important pieces of data: It takes 1.2 HP to run the A/C and it's too much current for my little treadmill motor!

I decided to bump up the voltage to see if it would lower the current for my next test.

Test 2:

Pulley on the treadmill motor: 3" diameter
Pulley on the A/C compressor: 4.5" diameter (stock)

Voltage: 48 volts
Current: 29 AMPs

Well, the current went up! It went up because the compressor was at a higher RPM and more load was on it so it needed more power.

For my next test I am going to stick with 36 volts, but go to a smaller diameter pulley. I have a 2.625" pulley that I am trying to get onto the motor shaft and I have found a 1.93" pulley online that I may order up after this next test.
Civic EV
Solectria Force
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mechman600 (09-02-2012)