Need some advice on old school charging systems

[super55]

I currently picked up an old '42 Ford GPW jeep that I was able to get running but having some issues with the charging system. My ammeter is reading zero and barely moves when key is put in run position. Ammeter goes to 60v and its only a 6v system so I don't know if there is more resistance in the ammeter than a standard 6v would be or no difference.

Anyways I put a voltmeter on the generator and both leads are kicking out about 12v to the voltage reg and the lead from the voltage reg to the ammeter is putting out about 8v DC to the ammeter yet it is still not charging the battery. I have a disarray of disconnected wires right now but the schematic shows it must charge by going back through the ignition switch to the solenoid back to the battery.

Is it possible to just run a jumper wire from the output lead of the voltage reg directly to the batt or solenoid to get it charging without burning wires? It's an old system so nothing on it is fused.

 

[reb]

The ammeter measures current (amps). It is probably 60 amps max, an acceptable value. The resistance of an ammeter is nearly zero. It doesn't matter what the voltage of the system is. The voltage drop from the output of the regulator to the ammeter should be millivolts, essentially zero. Sounds to me like there might be a wiring problem.

 

[Soundguy]

as said.. a -60 0 +60 ( center 0 ) ammeter is fine... most ammeters today like thaose gauges are shunt voltmeters anyway. .. shunts are near 0 resistance.

if it is instead an amperage gauge.. 0-60 i'd loose it unless it is original.

ordinarily a center 0 meter is more usefull. As said.. it reads in amps.. not volts.

here's a VERY good way to wire your gen, vreg and loads, and maintain a proper 'NET' charge / discharge system.

field from gen to field on vreg. armature on gen to arm/gen on generator. ground on gen to ground on vreg ( if they have them ). bat on vreg to one post on ammeter. other post on ammeter to hot side of start solenoid.

Now.. ALL power loads need to come off the same side of the ammeter as the VREG. NOTHING ELSE goes on the other side of the ammeter that is hooked to the battery. If there is a fuse panel, run a wire from that vreg side of the ammeter to feed the fuse box. IE.. the wire that feeds the ignition coil via the key will come from that side of the ammeter. if you wire headlamps.. run them thru a fuse.. from that side of the ammeter / fuse box. NOTHING at all on the other side of the ammeter except a line to the hot side of the start solenoid.

that's a real common, simple wireing scheme that works, and shows you if you are drawing too much load ( lamps, ignition, radio.. etc... ) by deflecting the ammeter into the negative. otherwise... the positive deflection you should see is what is charging the battery.

after startup it should be high and taper off to just a few amps positive.

 

[super55]

Thanks guys, I was originally looking for a way just to get the charge back to the batt but this rewiring advice sounds like something that will make the job a whole lot easier for me in the long run.

Its a -60/60 ammeter. When I turn the ignition switch to on I get just a touch of deflection in the +60 direction but never moves after that. After reviewing the schematic some more the way it is wired up now it is wired from the ammeter to the light switch to the ignitions switch. I peaked underneath the dash and it's a mess of splices and taps from only god knows why. I do like the alternative way you described Soundguy, Can't seem to figure out why they never had it that way initially.

I plan to put in a fuse block and plan to rewire pretty much everything anyways just because the wires are in such disarray and old that it will be much easier to just rewire and then all circuitry will have protection.

 

[Soundguy]

that basic wire diagram i detailed is pretty much how a ford tractor is wired.

should work fine for you if you have a vreg, and not a tickle switch lamp switch and cutout relay style setup.

 

[Soundguy]

ps.. if you get positive deflection.. someone may have changed polarity on you at some time.

when you rewire it. you should get negative deflection with key on.. or lamps on.. and then positive deflection after started and revved up

 

[super55]

Thanks for the tips Soundguy

Right now just by looking at the meter I can tell it's not the original because its the only one with a chrome bezel on it. When you refer to polarity are you referring as in the leads from volt reg/ammeter and ammeter/ignition are on the wrong terminals of the ammeter or that it could have initially been a 6v pos ground electrical system. Could crossing the F/A leads from the generator to the voltage reg cause this as well?


I haven't researched yet as to what it originally had but as the battery is hooked up as a 6V neg ground and am having no issues with it starting or running. Just getting a charge to the batt.

 

[Soundguy]

polarity is polarity.

a meter will read backwards if it was installed as one polarity and then the polarity was changed. ( like a change in ground.. or wireing a meter backwards )

you NEVER EVER switch F/A leads ont he generator and the regulator.. that is.. unless you like spending money...