Ammeter gauge wiring...

[shadetree]

So after all this bickering... how the fawk do I wire it up??

Re-read my first post.shady

 

[Will]

Ammeter's were common on old cars because the generator was on the order of 35amps and it's cool to have a gauge that says charge-discharge. An old car had no electronics that needed to be at full voltage--it was okay to drive around with your idiot light flickering as long as it went out when you rev'ed it. The need for a high-amp alternator is not for battery charging--it's to power all of that crap.

A good group 24 battery might have a 65 Ah rating. A 90% battery can only accept 10% of it's Ah rating--after a normal start your alternator will only be able to get 6 or 7amps into your battery. A 50% discharged battery--you left your headlights on for an hour or so, say--can only accept 25% of it's Ah capacity, or about 16amps. A fully depleted battery can accept 40% of it's Ah rate--26amps.

I think under most circumstances a 60amp ammeter would be okay. But amps grow pretty quickly in a piece of shit 12V system--your ECM, fuel pump, halogens, power window switch or some combination of these and leaving the lights on for a couple of hours by accident and you are screwed. I would not install such a device because it is too small for what almost any modern alternator can output. You would be adding a weakness into an otherwise robust system. It WILL fail because it can.

A voltmeter tells you all you need to know.