Hi group. Ethyl the tool truck's(1955 C600 W/272 Y block) 6 volt NOW REVERSED POLARITY TO NEGATIVE ground charging system is not charging the battery. My mutimeter shows 6.5 volts for battery power charge on a non running engine once I recharged the battery. When running at a high idle there is only 6.20 Volts at the battery. Now that the polarity has been CHANGED to negative ground, what is the procedure to check the 6 volt generator to see its out put? What is the procedure to check the now NEGATIVE GROUND regulator. I see lots of stuff on line instructing the diagnosis of 6volt charging systems but none discuss how to do a diagnosis if the polarity has been reversed. Am I over thinking this?

 

If you have reversed the polarity, Pos. to Starter & Neg. to ground, I would reverse this just like it was originally when the truck was built. Polarize the generator (I'm going to have to check the book to know what to do or someone else can tell us), a generator shop may be able to check your regulator is OK but I doubt it if it has been running on reverse polarity.
TractormanBill

 

The procedures should be exactly the same as when it was (+) ground.

Why are you running 6v (-) ground? What advantage?

 

It would be a disadvantage as far as the coil spark is concerned.
TractormanBill

 

hey guys, I would have stayed with positive ground instead of having reversed the polarity months ago if there werent other issues.....The 18 foot dry box van outfitted as a tool store that sits on the frame of "Ethyl THE Tool Truck" is powered by its own battery pack, an 8kw Diesel generator and shore power when its available. It would have required a lot of engineering to isolate the grounds to accommodate the needs of the tool store electrical needs to remain positive ground. The electrical shop who did the reverse of the polarity months ago now, told me he could make positive ground work with the stuff that gives electrical abilities to the tool store in its box but it would have to have expensive technology utilized similar to what is on a submarine. Seemed crazy to me at the time and still not to just do the simple reverse of polarity.

Update on why the charging system isnt producing a charge...so far the generator that had the polarity reversed all those months ago HAS FAILED. I took it out of the truck and ran it back to the same electrical shop and they tested it. They also verified a used generator I had as a backup worked. They also reversed the polarity on that used unit for me. Ive installed it. Im waiting for the paint to dry on my battery tray before putting the battery back in to test it....I have a new regulator ready to go here sitting on the shelf. I will run this with the old regulator after the paint dries to see what voltage is produced...

 

It's not clear what you mean by "new" and "old" regulators, 6v/+, 6v/- ? Where did you even find a 6v (-) ground regulator? Is it a Ford regulator?

I'm tempted to say you should go to a 12v/(-) system with an alternator that has an integral regulator.

 

Sorry for the confusion. when I said "the old regulator" I meant the unit that was in the truck when I bought it last November. It is a 6 volt positive ground regulator. It was reversed polarized last April by Broadway Auto Electric here in San Diego. I just now replaced it with a new positive ground regulator that I on installation reverse polarized so that it is now negative ground.

Having just replace the generator and retesting it still with the same regulator mounted as what was installed when the battery was let to run everything and ran down to zero, only 5.10-5.50 volts were produced. I then also replaced the regulator with a new unit and polarized it negative. Now the volt reading at the battery is 6.33 volts with a pretty fast RPM. Is 6.33 a good reading????----seems low... That 6.33V is what I have with the generator that earlier today Broadway Auto Electric tested and made into a negative ground component. I saw the bench test and conversion myself, the generator produced 7.25 volts on his bench. He also tested the generator that was on the truck when my battery went dead and that generator was producing zero volts.

For absolute clarity, today just an hour ago, I reinstalled my now fully charged 6 volt battery back in the truck. I replaced the generator and the voltage regulator and with my multimeter checked voltage and found 6.33 volts being produced at the battery.

 

You should be seeing 7+ volts. How is the voltage at high idle with headlights on? It could be the regulator just needs adjusting. Check all your grounds, especially at the regulator.

 

I will check volt readings with the lights on etc in the morning. The truck being a very big girl lives across town in a secluded location...How does one "adjust" the regulator? I will run another ground from the regulator to the frame tomorrow also to remove that from the equation.