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How to make home made alternator bench test?

12-05-2020, 06:29 AM
I want to learn everything there is to know about alternators- testing, repair, how they work, etc.

I can mess around with the alternator in my truck, but it's hard to get to.

So my question is, can I buy an electric motor, bolt it to my bench and run an alternator off of it to test alternators?

And if so, what specs on the electric motor would you suggest?

I figure I would need the following part:
Electric motor- 110V, variable speed, ??? rpms, ??? horsepower?
Some type of controller to increase or lower the rpms of the motor?
Some way to display the rpms?
A battery so the alternator doesn't run with somewhere to take the charge?
Some electrical equipment to drain down the battery so the regulator has to actually do its job?
Electrical connections
Safety shield for spinning bits n things.

01-28-2021, 10:40 AM
If you want to test a full load, then take the HP of the alternator and match it with a somewhat larger motor.

For example, if the alternator is 200 A at 12 volts, then it is producing 2400 watts. At 746 watt/hp, that says the motor needs to be at least 3 hp.

That's a pretty big electric motor, so you might find that most testing is possible without operating the alternator at maximum output.

Desired RPMs can be matched with appropriate pulley sizes.

You don't need a battery as a load, you need a high power resistor.

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