amp meter??

I have a cheap set of gauges for the lemons car. Ive lost the instructions after just hooking up the temp and oil. How does the amp meter wire up??

thanks.

I don't like ammeters for cars. I would recommend doing away with the ammeter and installing a voltmeter instead. An ammeter has to be in line with the current flow that it is measuring. This means you need some big wires running from the engine bay to your dashboard. I don't like the idea of routing the entire alternator output through the dashboard. If you use a voltmeter instead, very little current flows through those wires and it still gives you a good idea of the health of your charging system.

If you really want to use the ammeter it goes in series with the alternator output. Google is your friend - there are several easy to find schematics showing how to hook it up.

I second that. A voltmeter is more useful than an ammeter.

I had an ampmeter act as a very effective fuse. Instant dead car.

Agreed, all current (besides the starter) has to be routed through the ammeter, adding weight and complexity. You can deduce the same information using a voltmeter (i.e. battery getting low or not charging.) Honestly, if your Alternator light on the dash is working correctly, I wouldn't bother with the meter.

I've added one when I suspected that I had a failing alternator. They're great for that purpose, but not much help otherwise.

You can build an amp guage with a voltmeter across a known (very high) resistance placed in parallel with the total load but... really its pretty useless. Especially in a race car, you really don't need any gauges. Idiot lights with safe thresholds are better. (My opine... not a statement of fact)

Its the same idea as a shift light - you don't have time to look at the tach so you configure a series of lights to let you know its time... do the same for oil and water temps. The light comes on yellow... slow down, light comes on red, shut it down. Anything else you pull off the data logger - its irrelevant when you are in the car.

Everyone is right. Read this.

http://www.madelectrical.com/electricaltech/amp-gauges.shtml

Ideally, you'd have both voltmeter and ammeter to give a more complete picture. For a race car, a voltmeter is and easier and lighter installation. An idiot light would be good, as noted above.

Personally, I like my ammeter in my Valiant, and will keep it. Like anything else, you have to make sure it's installed correctly and maintained. You also have to understand what it tells you and what it doesn't.

Like dear old Dad used to say, an ammeter tells you what's going on right now. A voltmeter tells you what happened last night.

Many of the issues with ammeters concern the bulkhead connector and age, not the ammeter per se. That's easily corrected with new wiring and connectors.

Couldn't you run the power through a shunt,and then run small wires for the gauge which would be operating on Milivolts instead. This is how we do it in the telephone world,and I also know my 74 REPU does it this way as well.

In reply to Mazdax605: Sure, basically an ammeter using a remote shunt, but I'm guessing that the OP doesn't know how to hook that up.

Shouldn't be too hard. I am guessing Mazda in the 70's wasn't the only company to do it that way,so there may even be shunt connected Amp gauges you could score from any number of salvage yard cars of that era.

The gauge just came in the set of cheap gauges we bought for the lemons car. Really didnt need it, just thought since I had some time Id hook it up. Looks like its more trouble than its worth.

Thanks for all the GREAT info!! Im going to get a volt meter to put in its place.