ammeters are very nice to have when you have equipment that has a high electrical load demand.

When properly installed to measure charge/discharge rate of the battery, the ammeter will NEVER take the full load of the alternator. Any current that goes to immediate use (lights, motors, injectors, etc) does not have to run through the ammeter to the battery...

Lets say you have a 120A alternator, and the vehicle requires 50A to run... The most current you could ever have running to the battery is 70A, and that would only happen if your battery was registering 0v. After your battery charges fully, there will no longer be a voltage difference between the battery and the alternator, and the current through the line will be 0.

The best way to install an ammeter would be to use a digital measurement where the charge cable meets the battery and put the display inside the cab.

 

I know this is outdated by now, but I'd like to start off by apologizing for the temper tantrum earlier in the thread. Secondly, we ended up installing a volt meter, and a vacuum gauge, instead of a voltmeter and an ammeter. I'd upload pics, but since I'm not a paying member, I cant. Dad claims that with the vacuum gauge there in sight as a constant reminder of how far his foot is into the throttle, it's helped him to get about another 1.5 MPG out of it, on top of the 14-16 he was getting before. Lastly, between creating this thread and now, there has been much learned on my part; and I'll leave it at that. Thanks for the help...and life lessons.