Hey gang, So I converted the 52 truck to 12 volt this weekend, and used the Classic Parts alternator conversion wiring harness -- probably most of you would have avoided it. anyway, that system has me hooking the line to the ammeter to the negative terminal, instead of the positive terminal where the battery line used to go from the voltage regulator. now, the ammeter registers dead even all the time. Talked to the tech guy at the company that actually made the harness, and he said that's just the way it is, and you really can't run those old ammeters in any meaningful way with the 12 volt conversion and alternators. Does that sound right? is it something to just ignore? Thanks! Eric
In order for an ammeter to work the current has to go through the meter. At least one wire needs to be attached to each side. Assuming the ammeter is capable of handling the load in the system it should be connected as original. Exceptions to this would be: ... changing from positive to negative ground (old GMC) ; swap wires between posts on the ammeter ... much larger currents than the ammeter can handle I put a '54 GMC ammeter (from a 6 volt positive ground system) into my '57 GMC (12 volt negative ground system) because I liked it better than the idiot light that GMC used in the '57 small trucks. My truck has A/C and an aftermarket radio, but is otherwise stock. Works great.
That tech advisor needs to go into another line of work. Just as Bill said, current needs to flow through the ammeter for it to register. There is no "to negative" anywhere in the charging system. Perhaps he is confusing the amp gauge with a volt meter which does have one side hot and the other to a ground. Also amps are amps, there are no 12v or 6v amps so if your gauge can handle say 100 amps then that's it, six or twelve volt---no difference. The same end source on six volts will draw double the amps as on twelve. Here is the circuit for your charging system: from the battery terminal (big wire) on the back of the alternator to one side of the amp gauge and from the other side of the gauge to the positive post on the battery. If it reads backwards switch the wire positions on the back of the gauge. In real life one usually runs the wire from the alternator to the wire that went on the "BAT" terminal of the old regulator (unhook from reg.) which already is on one side of the amp gauge and the wire from the other side is already on the same post on the starter as the positive battery cable so it amounts to the same thing. The wires to the lights, radio, heater, etc., go on one post of the amp gauge, I'm almost certain it's the battery side not the alternator side, so the needle will show discharge when something is on. For peace of mind I like to run just one wire from the gauge to a fuse block on the inside of the firewall so there is some protection in case of a short.
These people may help. They dont list prices which means to me "If you have to ask the price we cant afford it". They sure have pretty pictures & would love the gauges but 120-mph for a 235 is a streach of the imagination. I have the amp meter and it works fine but as Evan said it only shows 1/2 as much with 12 volts. http://www.speedometershop.com/enc-pag.htm
Ammeter As I recall from my electric classes way be when going form a 6 volt to 12 volt will cut the Amperage draw in half which is one reason why the change was made to 12 volt lower amperage draw means smaller lighter wires ( aircraft use 24 volt systems to make tehm even lighter and gernerally run 20 to 24 gauge wires) THe Tech rep you spoke to must be living in India or someplace without Electricty. As the guys have said you need the wires on your meter wired as before with the battery to the positive lug and the "LOAD" to the negative side of the meter the Negative side does not go to ground. Bill
web addy Ken gave me this address a ways back maybe it will help http://chevy.oldcarmanualproject.com...ring/index.htm
our ammeters will handle 12v. no problem. They measure amps, not volts. Incoming power goes to the terminal on the left, as if you were reading the guage as normal.
