Need Alternator Help

[MjAllTheWay]

I have 6 lights and a red top optima but still my lights dim at idle if thay are all on at one time what kind of alternator comes stock on a 88 Comanche.Or how do you tell how many amp my alternator is.

[jimoshel]

Usually the amp rating is marked on the alternator somewhere. To get a idea of what it's putting out take a amp meter,at idle 60amps should do it but 100 would be better.hook the negative side of the meter to the pos terminal of the alt.Hook the pos terminal of the amp meter to a carbon pile. Remove the pos battery terminal from the battery. The amp meter will be reading the alt output.

[MjAllTheWay]

sweet sounds like a fun thing to do.

[-600JeepMJ]

Most parts stores or places that sell battery's will test your charging system for free. :brows:

[knever3]

Most alternators are hot rated, which means they are rated at a certain rpm like 2000rpm. If your truck idles at under 1000rpm you are not getting say 100amps it's rated for. The only way to do this at idle is to get a alternator rated 100A at that rpm or getting a smaller pully for it so it spins faster at idle.

 

Some trucks came with 60 or 85 amp units so check to see what one you have first.

[1990 Pioneer 4x4]

I got my alt. respooled twice (gotta stay out of the water). It’s rated at 120 amps. With two red tops, I don’t have any problems with the winch, lights…

[dasbrick]

Could always get a pull throttle.

 

We have one on our old rescue truck to keep the RPMs up around 2500rpm to not drain the battery with the strobes and lightbars. It basicly is just a pull knob that has enough tension to hold a certain position on the idle cable. thought about one myself.

[dakineJ]

Be sure to check all of your grounds,so you know that your charging as efficiently as possible.Can make a big difference.Check cables,consider replacing.Google kelly's work's in progress, I'll try to find the link.