Have you tried a 12 v gen in 6 v system?

55 50 Ron · Jul 29, 2017

I suspect some of you have used a 12 v gen in a 6 v system and had it work successfully. I'm working on a 6 v pos ground system that was reported not charging. I found the gen to be labeled as a 12 volt unit. It has a "new" 6 v pos gnd voltage regulater. Ammeter shows small charging, but I measure only 6.5 volts at the battery posts which is too small to really charge so the ammeter showing charge puzzles me.
Battery is a new Delco and my next thought is to charge the battery for awhile from an external charger. Yes I did polarize - I know about that. Have also cleaned rust and paint from various places so the VR and gen have good chassis connection. I'm a "sparky" but feel like this system is outsmarting me! Oh yah, the question will probably come out "Do I know for sure that the gen is good"? No I don't and that will be another avenue of "research".

As you can probably tell, I'd rather write about it instead of work on it, LOL.

Bob · Jul 29, 2017

Momentarily "full field" it and note any Voltage or Amperage rise. To do this you need to know if it's an "A circuit" or a "B circuit" generator. As an example, Delcos are typically "A circuit" and you ground the "F" (Field) terminal to full-field them.

Speed is also relevant to the output voltage, a 12 Volt generator belted up so as to turn extra slow relative to engine speed would behave much like a faster-turning 6 Volt unit, within limits, IMHO.

gene bender · Jul 30, 2017

You need to go back to the 6v gen. If you ground the fild that should make it charge. If it doesent charge with field grounded the reg is bad. Volts do not make an AMMETER show charge it measures AMPS not volts. Are all componet grounded to the frame.

teddy52food · Jul 30, 2017

No charge with the field grounded means the generator is bad. Check the voltage on the A terminal & if it raises the regulator is bad if it doesn't show at the battery.

John T · Jul 30, 2017

Ron, I have used a 6 volt genny to charge at 12 volts by changing the VR, never tried 12 to charge a 6 but a 6 volt VR "might" work as long as the genny itself is good (NO warranty). NOPE 6.5 isn't gonna put much charge to a 6.3 volt battery, 6.5 and up to 7+ is more like it.

I'm sure you have seen my Charging Troubleshooting Procedure, it can help diagnose the cause of non charging to see if its a genny or a VR or other problem. It includes the full field grounding the FLD post teats as well as the motor test for gennys.

John T
John Ts Charging Troubleshooting

M-MAN · Jul 30, 2017

I was told years ago that a generator puts out amp's, not volts. Volts are a voltage regulators job.

sotxbill · Jul 30, 2017

It will work just fine as long as the correct vr is installed. The gen does not know or care how much, the vr does that.

Now.. the windings in ALL generators are SIZED for a certain current level. You can NOT exceed the current rating design on that generator. So the current limiter setting in the vr must protect the generator from over current or you will melt the solder out of the armature and burn brushes.

6 amps of charge should show a voltage rise on a good battery, unless the battery is bad,,, or the amp gauge is not reading correctly. Measure voltage on battery not running and then running to see if your really charging. check voltage on battery not running to see the condition at rest. A bad cell will simply suck current and not let the voltage come up to 7 volts.

dr sportster · Jul 30, 2017

To test generator read John Ts number 8 .

55 50 Ron · Jul 30, 2017

I was surprised again at HOW EASILY something written can be mis-read and thus mis-interpreted. Thanks to everyone for responding. Some of you said "an ammeter reads amps, not volts" which I know and which I didn't say, but in re-reading what I wrote, I can see where you could mis-read that into the message.

Sorry, next time I'll try to be more clear. Meanwhile, I'll get back to solve the problem.

Have you tried a 12 v gen in 6 v system?

55 50 Ron

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Bob

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