I'm getting my plans together to convert my '49 to 12V. (Making a Christmas list.) All seems straight forward enough. I plan to build a 6V power supply for the minor stuff I don't want to mess with, such as the instruments. My question is what do I need to consider when going from positive ground to negative ground. Can the starter wiring be reversed easily or is it grounded through it's case? Same for a typical heater fan or should I replace its' motor and controller with 12V units? Is there anything else that would be polarity sensitive?

Thanks in advance,

Johann

:-X12

 

if the search functionn comes back there were great articles in there that i used to clarify my questions. i cant remember the info off hand to answer though sorry.

 

[updated:LAST EDITED ON 07-Dec-02 AT 09:54 AM (EST)]Johanne,

Grant pretty well covered it. The only other thing I can think of is the horn. If you have a 6V relay (some do, some don't...I don't know if the 49 had one or not), it should be changed to a 12V relay but the six volt horn will take 12 volts fine...although it will be louder. Or, you can just change the horn to 12 volts. I've always used the six volt horns on 12 volts with no problem.

 

Grant, that's a great run down, but one hour!? I think I had seen it before but I couldn't remember where. My knoweledge of electricity (BSEE) tells me the starter and heater fan will turn backwards, and that isn't mentioned. Anyone know if this is a problem?

BTW the main accessory I want to add is modern blinkers so I can keep my arm inside and warm. A radio would be nice, though.
Johann

 

My
>knoweledge of electricity (BSEE) tells me the starter and
>heater fan will turn backwards, and that isn't mentioned.
>Anyone know if this is a problem?

These are not polarity sensitive. Otherwise I'd have 1 forward gear and 3 reverse.

>
>BTW the main accessory I want to add is modern blinkers so I
>can keep my arm inside and warm. A radio would be nice,
>though.
>Johann

Since your breaker box will be 12V, you can take power off it for turn signals. Radio the same as well as wipers and whatever else you want to add on.

The heater being 6V will require an inline Voltage Regulator available at most any top notch parts house or one of the many suppliers. Just make sure to get one big enough to handle the amps the heater draws. They do get hot, so mount it away from combustible material.

 

I put a 12v alt on my 48 it starts great new bulbs bought a set of mecanical gauges all is fine oh ya 12v neg ground

 

Well, my 12V conversion is complete and I was surprised how simple it really was. Lots more than one hour, though. The bulbs themselves took longer than that.

I opted to replace the field coils in my generator rather than getting an alternator. Getting the old ones out proved to be the hardest task. Runs at about 14V charging with the new regulator.

I replaced the ignition coil, although I probably didn’t have to, and added a ballast resistor. The new starter solenoid has an extra contact to cut the ballast resistor out during starting. It now starts much quicker due to faster cranking and, I think, stronger spark.

One part I had to add was a new starter button. The old single pole button wouldn’t work as the new solenoid needed 12V to energize it, not a ground. I wired the new button from my ignition switch so now it now longer will crank without the key.

Starter and heater fan have series wound field coils, so if you reverse the polarity on the armature you also reverse the polarity on the field and it spins the same direction. This wouldn’t be true for a permanent magnet motor. I also opted to put a “ballast resistor” in series with the heater fan to drop the voltage. It generates some heat, but after all, that’s why I’m running the fan. The heater really screamed at 12V.

For the instruments I put 30 ohm, 1 watt ballast resistors in series with each. Works great. My fuel sender is the wrong type and will need to be replaced. Oil and temperature work as they did at 6V. Ammeter needed the feed wire looped through the opposite direction.

The previous owner had an aftermarket turn signal system installed, but the 6V flasher was junk. I bought a new flasher and a trailer hitch converter module in order to use one filament in my single bulb tail lights for both the brakes and turn signals. The other filament is the running lights. One thing I discovered was that with this set-up, if my front blinker bulb burnt out, the tail light wouldn’t operate. Not wanting a single bulb out to be a problem, I added a 10 ohm resistor as a second “bulb” in each blinker circuit.

Next up, fix the horn. I’m pretty sure I can adjust it as I had to do to get it to work at 8V. If I have to replace it, there are lots more options at 12V

Johann

 

>
>One part I had to add was a new starter button. The old
>single pole button wouldn’t work as the new solenoid needed
>12V to energize it, not a ground. I wired the new button
>from my ignition switch so now it now longer will crank
>without the key.
>

I placed an old horn relay between my new solenoid and the old starter switch. Grounding the starter switch energizes the relay and provides 12V to the solenoid. I just really liked the look of the old chrome starter button and didn't want to give it up.

Scott

 

We had an old forklift one time, and what they did was mount the solenoid on a phenolic pad which insulated it from ground. Then they ran a wire from the solenoid housing mount bolt to the starter switch. I guess plastic or rubber would work too.