Alternator Power Output

[farok]

Is there a good way to figure out how many amps my alternator is good for? Similarly how much power it's outputting already so I don't overload it? I'm looking at DC-DC chargers for the house battery and don't know if I should opt for a 20, 30, or 40 amp charger. Thanks!

Chris

[cadillackid]

the alternator output max is determined by its model number.. many are labelled with their amps (at 12 volts DC)...



only real way to see how much juice you are using is to measure it..

DC clamp on meter on the red output wire of the alternator while you drive?

[farok]

Thanks. I'll see if I can see any labels or tags on the alternator next time I pop the hood, and start there. The VIN wouldn't help here, I assume?

Chris

[ermracing]

Originally Posted by farok

Thanks. I'll see if I can see any labels or tags on the alternator next time I pop the hood, and start there. The VIN wouldn't help here, I assume?

Chris

If you could get the build sheet from the VIN that might tell you what alternator it was equipped with from the factory. However, if it was replaced down the road somewhere, it may or may not be the same.

[john61ct]

Mfg rating and paper docs will **not** tell you how many amps an alt will actually output for more than a few minutes or seconds, in **that** vehicle, in **those** ambient temperatures.

In real life, the VR fitted to the alt can be more critical than the alt itself.

Get an ammeter and a large high-CAR bank, depleted to 50% SoC and measure what the bank can pull.

If testing for an extended period, or if the bank just isn't pulling enough, might need a large load device as well, like an inverter feeding an adjustable electric heater, induction stove or similar.

Most stock setups, you might be able to pull half the rated max in even cool conditions.

If pulling big loads, rather than investing in a huge alt + sophisticated VR like Balmar MC-614. a DCDC charger will help keep V & A well regulated, protecting both the alt/VR and the load side.