Can a 12V generator be rewired/converted to 6V?

[kilohertz]

Hi guys,

Just discovered why my 1952 MC is overcharging the battery...someone has put a LUCAS 12V generator on it. After a little sleuthing and rubbing off years of dirt, I found it stamped Lucas and it's a C39 12V genny, pretty common, but the wrong voltage. Is there a way to drop this bad boy down to 6V, remove a brush, rewire something internal etc?

Last resort would be to go find a 6V generator. As I just had the starter rebuilt, and bought a new 6V battery, I don't want to convert to 12V.

Thanks

[Lavoy]

I would assume it can, but would require new armature and windings. Before I would go to that expense, I would get the correct generator and have it rebuilt.
Lavoy

[Stan Disbrow]

Hi,

Well, probably not that Lucas generator. The original Delco generators came in 6, 8 and 12v using essentially the same cases. So, swapping out field coils and armatures could be done fairly easily. One would have to research that Lucas and see what they were up to.

Is the Lucas internal or external regulator? If external, just swap out the 12v reg for a 6v one. If internal, then some interesting rewiring would be needed. If it can't be repolarized to Pos Gnd, one could leave it Neg Gnd.

Same goes if that Lucas is actually an alternator. Keep in mind that the regulator passes current into the field coil to produce a magnetic field. Or not. So, the voltage limit is maintained by the regulator.

It is the maximum voltage which is determined by the coil windings of the field versus the armature. So, one can limit a 12v unit to 6v by the regulator. But, one can't make a 6v go up to 12v in the same manner.

There is also the concept of using a small 12v battery for the alternator, then passing that via a separate electronic voltage regulator circuit into the 6v system. By this I do not mean a vehicular voltage regulator but something from the world of electronic power supplies. JC Witless used to sell such things to go from any voltage and ground over to other ones. The most common being from 6v Pos Gnd to 12v Neg Gnd for VW Beetles and Buses.

But, before I did that, I would be grabbing up an original Delco 3-brush gen for the MC and Be Original.

And, before anyone asks, the M series did not use voltage regulators, but a third brush feedback into a two-position dash switch for Hi and Lo charge. The third brush was on a movable strap on the Gen to set current. Mainly to that needed to run the two lights (not enough current for a 3rd light). It worked very well.

Stan

[kilohertz]

Gentleman, thank you for the help.

Well the Lucas is a generator, with an external regulator, although the person who mounted this has just connected the wires on the rear connectors for full output. It is very similar to the unit in my MGB, external regulator.
Yes, that 3rd brush is what I went looking for but then realized it was the completely wrong genny. It's a neat method of controller charge. I looked around town for an old Delco but none were to be found. My neighbor has an MC as well and they fried something behind the dash panel when they connected a battery incorrectly. They may be going to 12V and if so, said he would trade my 12V for his 6V generator, otherwise, there is an auction at a local farm this weekend and there is an MC there, and who knows maybe some spare parts. It's been on the farm for a long time. May just have to bring the whole machine home.

Definitely want to keep it original, 6volt and with the generator. I was thinking of the solid state regulator idea, but that would mean something big enough, say 20A to charge battery and run lights etc. and probably more work than it's worth.

I'll just try to find a Delco and set it up as original.

thanks!

[Lavoy]

I probably have one if you need one.
Lavoy

[MikeH]

Yes it can be converted. Have a check on these i found. i also found them useful converting my generac generator.

http://www.how-to-build-hotrods.com/6v-to-12v.html
http://matchlessclueless.com/electrical ... onversion/