6 Volt Generator

I was talking with a co-worker the last few weeks and his dad ran a repair shop thru the 1950's & 60's. He said his dad would take a 6 Volt generator and add a 3rd brush inside of it and it would convert it from 6v to 12 Volts. Has anyone ever heard of this procedure before?

Dad used to convert farmall generators from 6 to 12 volts.

Third brush generators are regulated by the third brush and usually only have a cut out with no other regulator. The generator voltage output can be adjusted by moving the third brush. Some generators have enough adjustment to get them to put out 12 volts, but I would expect their life to be shortened.

My Case LA was converted to 12 volt by replacing the field coils. The original regulator was adjustable to 12 volt. Has worked well and all original exterior parts.

Gene

Sure it can work, but you don't need to add a third brush to make a 6 volt genny charge at 12 volts. In fact, depending on the location of the third brush relative to the fixed ungrounded brush next to it, you could have LESS charge then if it remained as a 2 brush where there's less resistance and voltage drop between the 2 brushes. The third brush are the older system gennys where charging could be limited and regulated by moving the third adjustable brush further away from the fixed brush. A genny dont necessarily know what its output is supposed to be, it increases if it turns faster or you pump more current through the field windings. Regulating field current is what a voltage regulator does.

I have converted 2 brush 6 volt gennys to work at 12 volts simply by using a 12 volt voltage regulator. Don't anyone have a calf, I'm NOT saying it set the world on fire or charged at any high rate, I'm ONLY saying it worked. One potential problem with what I did is the field windings may be passing more current then they are rated for, that's why if a genny shop converts 6 to 12 they would change out the field windings to those with higher current rating. However my conversions (left old 6 volt fields in place) worked and never failed even if tis NOT engineering perfect or correct.

Hope this helps

John T

though it's contrary the the correct police they can,will and are being used, most generators don't charge much if any at idle whereas an alternator will,two big arguments not enough voltage but most can produce 17 volts or better,next can't stand the increased voltage ,first of all most 6 volts are built as good per-se as a 12 because of the high resistance of a 6 volt,next the max voltage and amperage output is only required for a short period if everything is normal,it all boils down to how much constant demand is put on the system, ie even though rated at the same voltage and comparable amp output, use one of the snuff can size high output alternators compared to a 34si delco with a 70 amp constant load see with one holds up the longest

In approx, 1950, IH went to a voltage regulator but continued the three brush generator for several more years.