Thread: ammeter (actually I was wrong - should read Volt Meter)

It is unusual to see an ammeter on an alternator equipped vehicle, and it is certainly not standard (and usually not a good idea). Not being standard, we can only speculate how it is wired. The standard wiring for an ammeter is so that all current to and from the battery except for the starter current flows through the ammeter. If this ammeter is installed like that, yes, the current being on the discharge side would indicate that you are using more current than you are putting out of the alternator.

However, since it is an aftermarket installation, and there are good reasons for not having alternator current flowing through the ammeter, it is quite possible that it is only showing current drain and not charge. In which case, it tells you nothing about whether you are drawing more current than your alternator is putting out. You should be able to check the situation by seeing whether the discharge from, say, headlights, is the same with the engine stopped or running. If it is (may increase slightly when the engine is running) either it is showing discharge only, or the alternator is not working. In that case you would expect the alternator light to remain on, and also, if the alternator is charging, the battery voltage will increase with the engine running.

Hope this helps,

John

Thanks John,

Odd - it looks original. Its in the top right of the dash console.. what do other people have in that spot in an 86 110 Isuzu? Maybe I'm totally wrong and it isn't an ammeter at all..

The needle moves farther to the left when the engine isn't on or is at idle. The battery light comes on when the ignition is on but the engine isn't, or when the alternator isn't working (that's how I knew of a broken belt a little while ago).

The plot thickens..

Dec

Actually, I must just be a volt meter!

Can I re-ask the question with a volt meter in place of the ammeter?

When you have no electicals happening, but engine running does it show positive amps? it should

So yes, negative amps means your consuming current in the other direction, ucing more than your produceing

As John mentions, you need to know where it has been wired in,

Originally Posted by flagg

Actually, I must just be a volt meter!

Can I re-ask the question with a volt meter in place of the ammeter?

Does it sit in the middle or far left when ign off? how about you show us a pic

I think you have misidentified the standard voltmeter as an ammeter. The + - at the bottom is menat to be a picture of a battery. SHould remain between the two red blocks all the time. Normal with battery fully charged and engine running at high speed is close to the RH red. Normal with lights on and at high speed is about the middle, depending on battery condition and wattage of lights. If it gets much below there and stays below when running, either you are drawing too much power or the fan blet is slipping.

John

Land rover call it a battery condition gauge, or some thing like that.

I had a dud battery a few months back, when I was on that battery it showed negative.
also if the needle is vertical when the motor is not running and the solar panels are turned off i know that she will not start on that battery, turn the fridge on and it moves to negative a bit.
turn the solar on and it moves back to positive