ammeter

Personally, I wouldn't bother with an ammeter. Instead, install a voltmeter. Simpler to install and gives you better information.

I took my ammeter out and installed a voltmeter.

If you are a purist, then you would run the leads all the way to the battery posts (like I did, and be sure to put a 1-1/2 amp fuse in the line) to get the most accurate reading of the battery's charge state and eliminate any line losses. Don't feel bad if you don't do it that way.