Voltage?
 

How much voltage should an alternator put out?

I measured the voltage on the line from the battery going to the master disconnect. With the engine off but the power on, I got 12.5 volts with a brand new battery. With the engine running, no accessories on, I got 12.8 volts. With the electric water pump and electric fan going, I got 12.8 volts. Both of those checks were with the engine at idle, about 800 RPM.

The alternator is supposed to put out 60 amps, and there's an 8 gauge line that runs from the alternator directly to the master disconnect.

Is this good or bad? I'm assuming that as long as it's at least 12 volts, it's good.

(edit)
I'm just thinking that the alternator (it's a Mopar, modified for 1-wire operation) has a regulator on it that doesn't turn on until 900 RPM. I probably should check it at about 12-1500 RPM.

Re: Voltage?
 

Yup. Should be around 13.7 but not at idle.

Re: Voltage?
 

I thought it was 14.7

Re: Voltage?
 

What should it be at idle?

At idle you should have 14-14.5 volts at the battery. Even though the alternator is rated at 60amps, it's probably putting out much less. Check the Amp output at the alternator. 8ga wire is fine, I only run 10ga without a problem and don't use a relay to the battery in the trunk.

If you need to upgrade the alternator, Summit offers the Powermaster 120amp which is great. Their catalog wrongly lists it as 75amps at $160, but I ordered one and it came with a tag certifing it as 120amps. It listed in the Mopar section.

Re: Voltage?
 

Don't bother checking at idle...

I don't have any way to check the amp output at the alternator - my meter won't handle that much amperage. I'll check the voltage output there, though. I didn't get a chance to do that. I'll also check it at a higher RPM.

I was looking at the Tuff Stuff 1-wire alternator. Does Powermaster have a 1-wire version?

You're using a 10 gauge wire with a 120 amp alternator?

Re: Voltage?
 

I have never seen over 14 with the Mopar Performance regulators or the older Chrysler alternators. 14.7 is pretty high for anything...

Yes, Powermaster does have a 1 wire version in Chrysler trim.
And I am using 10ga with a 120amp alternator. Haven't had any roblems so far. With the 1 wire there is no need for an external voltage regulator cause it's built into the alternator. I should note that I have an underdrive pully on the alternator.

Right, that's what I was looking for - no external regulator.

Oh... I just remembered that I have an underdrive pulley on the crank, I'll probably have to rev it up higher to get the alternator going.

Roger that. REV IT UP !!!!!

I'll give it a shot. Then I should have 14-ish volts?

So What was the voltage when you REVED It Up?

I didn't get a chance to do it yet. Wednesday...

I started up the motor, checked the output at the alternator. A little over 13 volts at idle. When I rev it up to around 2000 RPM, it's almost 14 volts. At the battery, it was almost 13 volts at idle, so I'm losing a little bit on that long wire from the alternator to the master switch. I wasn't able to rev it up and check the voltage back at the battery, I was working by myself.

The volt meter it getting it's power from the starter relay via a 10 or 12 gauge wire. That's getting it's power from the starter, via an 8 gauge wire. Could this be why the volt meter is showing a lower voltage than what's actual winding up at the battery? What should the volt meter be connected to?

http://www.iequus.com/assets/manuals/tge.pdf

Hope that helps.