is this a voltmeter or ammeter?
 

This is on the "bay"

http://www.ebay.com/itm/NOS-1939-FOR...dXDWWw&vxp=mtr

Sure looks like a voltmeter vs amp gauge. Which is it? If it is a voltmeter, is it limited to 6V? Who knows anything technical about this? Thanks in advance...

Re: is this a voltmeter or ammeter?
 

Its a voltmeter think it was refered to as battery indicator.
And is designed for the stock 6v pos gnd.

Re: is this a voltmeter or ammeter?
 

You have to look at the schematic for the 39 Ford to determine is this meter would be hooked up in series with the battery (ammeter) or in parallel(voltmeter). The gauge does look like a voltmeter as such is limited to 6V at the gauge. The poster of the sale list the part number as 99A but that would make it a Merc. voltmeter not Ford but also list the part number as an ammeter 10850. Contact the seller to make sure they have listed the P/N correctly. Then look it up in the Ford chassis parts book. the voltmeters are P/N -10844

Re: is this a voltmeter or ammeter?
 

An amp meter will work for 6v and 12v, a voltmeter would only work for 6v.

Re: is this a voltmeter or ammeter?
 

The general rule is that a voltmeter starts at zero and an ammeter starts in the middle.

Re: is this a voltmeter or ammeter?
 

Looks like the volt meter in my '39 p/u which had an amp meter in it when I got it. The amp meter has just a loop on the backside of the gauge that a wire runs through and the volt meter has 2 wire connections on the back if that helps.

Re: is this a voltmeter or ammeter?
 

Thought a bit more about it, since its a KS instrument and bimetal it doesnt care about polarity.
Converting it to 12v should be possible bypassing it with an external resistor...thats just my theory no real world test to back it up.

Re: is this a voltmeter or ammeter?
 

The eBay listing is a volt meter. You will need a resistor of the same value measured across the two posts on the back of the unit. Should be about 60 ohms. Wire the resistor in series with the gauge. That set up will work on 12 volts.

Re: is this a voltmeter or ammeter?
 

Voltmeter