Wiring an Amp gauge with Flathead?

Hi Guys,

I think I have this figured out correctly but sometimes it's nice to get some verification. I have a '38 Chevy gauge that has an amp gauge on it. I would like to wire it into my system that includes a generator and voltage regulator. I came up with this diagram. Am I correct that I want to wire it betwen my VR and starter solenoid/battery? Btw, I've already wired in an after market voltage gauge but would just like to get all of my stock gauges functioning as well.



Here's the actual gauge. I'm assuming that I would use the top and
bottom posts?

 

Yes, you would be correct. Wire it according to your diagram and you should be just fine. Check to make sure the fuse is big enough to handle the amps being put through.

 

Thanks John. Any guesses as to how many amps a stock generator is outputing?

 

It's probably 15 to 20 Amps. I'd consult a repair manual just to be sure.

 

Wiring it that way will never show a discharge, unless all of your lights, radio, & accessories are connected on the voltage regulator "bat" side of the ammeter. You want the ammeter to reflect the current that is not only going TO the battery, but what it is doing when the generator can't keep up with the load and the system has to draw current FROM the battery.

 

What Ebbsspeed said, but here's what it should look like.

That's assuming your "solenoid power" wire is what you're using to feed power to the rest of the system.

 

how would I wire my flathead with 1-wire alternator (which looks like a gen) to an ammeter gauge?

 

The Bat. wire going to the regulator would connect to your one wire alternator. BUT the rating of your ammeter needs to match or exceed the output rating of the alternator. Volt meter is a smarter choice.

 

question I'm using a '66 Mustang dash with amp meter but a 1 wire alternator is it doable and safe?

 

The factory Ford ammeter is either a shunt-type (with two wire connections) or a inductive type with no wire connections, but has a small metal 'loop' on it's back.

The shunt type won't work unless you can calculate the needed Ohm value of the shunt. Very difficult to do and if you miss it'll either smoke the gauge or read inaccurately or not at all. These were designed for a 45 amp alternator. These gauges were known for failing in OEM use. You can't hook direct alternator output to these like a aftermarket gauge.

The loop type will work but you do run the risk of killing the gauge if your alternator can put out more than 45 amps.