The Stovebolt Site Forums The Shop Area The Electrical Bay 54 12v alternator/coil/amm/battery hook up

I've replaced a lot of wiring but in looking at several wiring diagrams for 12v converted trucks I see some with wire from alternator to coil and other diagrams show wire from alternator to Ammeter with splits to lights and ignition, and coil to ignition. What's best? -- or both, wire from alt to coil to ignition? Right now it's alt - ignition - coil.

the alt would energize the coil when the starter was engaged even if the key was off, you don't want power directly to the coil, it should be switched - the power from the alt should go to the battery, power for other things comes from the battery terminal on the starter .... a 12V conversion doesn't really change anything, with the regulator out of the picture the rest of your 12V wiring should be the same as the factory schematic

Bill

Ok, so by "switched" you mean the ignition? Then the power wire goes from Alt to Amm and out to ignition. the blue wire from alt goes to ignition and out to coil.
While weeding out some old wires I found a ground wire connected to wheel well but not connected on the other end. It is long enough to reach dash so I'm thinking it must go to the lights???

the key switch on the dash is where power to the coil comes from .... the hot wire from the alternator goes to the ammeter and from there to the battery

after 60 years of previous owners, there's no telling what you find was for, if anything - study the factory wiring diagram to determine how things should have been and should be now

Bill

The factory schematic seems to raise several more questions: It looks like the alt to amm wire goes to the top amm post (+) and then leaves from the same post (+) to the lights and ignition while another wire goes from the amm (-) post to the battery. On some 12v conversion schems there is also a blue wire from Alt to ignition and ignition to coil. The slightly different terminology also is confusing, for example as I look at my ignition switch from behind there is a post at the top, a post at the bottom and a post on the left. I have the alt feed going to the left post and the blue wires (in from alt and out to coil) on the bottom post.??? And the wire from ignition to gas gauge is on the ignition top post. Also some conversions stress need for a ballast regulator between ignition and coil. Is this necessary since the truck ran ok without it - just needed a lot of cranking to turn over.
I hate being this stupid about this stuff and sure appreciate the expertise and patience of everybody on this forum.

If you have an internal resisted 12 volt coil, then no ballast resistor is needed. If you have a 6 volt coil or, a 12 volt external resisted coil then you need the ballast resistor. Hum.... looks like the factory had some 6 volt coils left over...for some years, and years. Then they went to an internal resistor....the spec for the coil itself did not change much it would seem. Actually that is good use of engineering resources, The original coil was well thought out and no big changes were needed. The real issue is the current at the points. That is what stayed the same.
The connections are to serve the following functions, 1, Ammeter is in the charge circuit. 2 Coil should go through the switch, 3 Headlights and dash lights are on the charge circuit. Gas gauge, radio if you have one are on the switch. Early trucks only needed two connectors. 1, Battery, and 2, every thing else. Starter was hooked to a floor switch and that went to the battery. Newer trucks have a spring loaded position to engage the starter solenoid. Newer still the Acc position was added. 54 would have been in the early group I think.

Ballaster resistor - resistor coil.

I thought a 6v coil produces 6v and a 12v coil produces 12v and a ballast resistor-ed coil produces 8-9 volts?

http://www.mossmotors.com/forum/forums/thread/5684.aspx

coils produce hundreds [thousands?] of volts, about the same regardless of battery input, some do it with 6V, some require ~9V, and the resistor is to lower the 12V to that ~9V, while the resistor bypass when cranking compensates for the lower voltage caused by the starter motor draw

Bill

the first part is correct, the alternator output goes thru the ammeter to the battery, and the wires from the ammeter to the lights and ign sw supply battery power to other things [ammeter passes current both directions, showing discharge when battery current is being used without that alt working] .... the wire from the alt direct to the ignition is an exciter wire that is necessary to prevent the engine from continuing to run when you shut off the key .... you do not want the wire to the coil from that same terminal or the engine can continue to run as long as the alternator is turning

as for position of terminals on gauges [I continually point out:], the factory diagram is laid out exactly as the wiring and components are seen in the truck, if you look at the schematic from the tail light end [bottom usually] then you are looking at the face of the gauges, if you look at it from the headlight end, then you are looking at the back of the gauges - the gauges and terminals are in the same left to right position as they are in the truck, just need to visualize a bit with the round AD gauge set

and you aren't being stupid, most folks find electricity is confusing, just don't blank out when faced with it, think things thru!!

Bill