Thread: 12 volt conversion.....

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I'm thinking about helping out the cranking on my 50 Pontiac..I've never done this before..I have a few ideas...1...add a 12 volt battery(charged regularly) and hook it to the starter only and retain the 6 volt battery and charging for the rest of the car...2...add a 12 volt alternator and figure out what kind of resistor I can use to power up the rest of the car... Are the old Mopar ballast resistors good enough to pull the deal off or is there something better out there????....Opinions please....

Several things that you may want to consider before performing this conversion.

This would seem to be a pretty straight forward and quick job, however, in addition to the starter; you’ll want to at least consider the ignition, lights, starter, instruments, windshield wipers and charging system.

If this is an occasional driver, the original ignition system may run fine with just the addition of a ballast resistor for the coil. If you’re going to drive this one more “than just around the block once a month,” a new 12 volt coil probably makes good sense.

If your current 6 volt is a standard coil found on most domestic vehicles you will need a ballast resistor. I believe most 6 volt coils are rated for 8 volts. Some aftermarket performance coils may work without a ballast resistor, and you could try your current coil – bearing in mind that 12 volts may ruin it. Using a true 12 volt coil will eliminate the need for a ballast resistor. Your original points will work fine in a 12 volt operation. The AC Delco U515 is a “universal 12 volt coil that does not require the use of a ballast resistor

Your condenser can be replaced by any condenser, i.e., AC Delco A202Z is a pretty universal condenser with an open lug and a side mounting bracket

If you don’t replace lights, the bulbs will begin popping like the 4th of July. You’ll need to change all of them – tail/brake, headlights, instruments, dome, license plate and trunk/under hood if you have them. The easiest way to do this is make a chart of each place a bulb goes, remove the 6 volt bulbs and head off to the local parts store to make sure the ones you select will fit. Most will be standard bayonet bases. Bear in mind, some may be a bit different in actual light produced. The headlights are the easiest as you’ll replace with a new sealed beam (go halogen) unit.-

The starter is easy - it will work well on 12 volts. The 6 volt starter is designed to handle a significantly more current a 12 volt starter. The solenoid needs to be replaced with a 12 volt unit as it will overheat with any lengthy cranking and could possibly stick in the ”on” position causing your starter to overheat and that’s bad. I hope is goes without saying that all cables need to be in good shape and very clean. If in doubt, replace them with nice new heavy ones.

The instruments are tricky. If you have the stockers and want to retain them, you can use a voltage reducer from AC Delco. The AC Delco U1745 has a 4 amp load limit. You will need one per gauge to do this right.

Good ol’ JC Whitney has a “12-Volt TO 6-Volt Wiper Motor Voltage Reducer – Part Number ZX737160X $38.95. It’s specifically designed for a 6 volt windshield wiper in a 12 volt system

The easiest and most common alternator unit is the GM 10SI or 12SI units. They have the internal regulator, and require only 3 external connections. They also gives you the option of using a 1 wire regulator (self-exciting regulator) which requires only 1 external wire. You may have to coble up some brackets or use some from a donor vehicle. Really all you need is a pivot bracket and a top brace to keep the belt tight and in line.

Hope this helps (and doesn't discourage). Oh yeah, one more thing - you can not have enough good ground. Clean and heavy gauge straps are your friend here!

Regards and Have Fun,
Glenn

I'm not recommending this method, but it does work...........to a degree. Back in the day when we would just do stuff to get it done and you couldn't buy all the fancy stuff we have today, we would make up our own 6 volt/12 volt system by installing a 12 volt battery, then running a stainless steel self tapping screw through the top of the battery exactly mid way between the positive and negative posts. Each cell is 2 volts, so the typical 12 volt battery has 6 of them, and if you tap down into the cells half way across you will get a 6 volt tap from which you can power stuff that can't be changed to 12 volt ones, like the wiper motor, etc.

The problem is, this is pretty much considered shade tree by todays standards and it also shortens the life of the battery somewhat as you are overworking 1/2 of the battery. We used to do this trick when we were swapping a newer 12 volt engine into an older 6 volt car.

Thank God we came out of those dark ages of car building, and I am only mentioning this as a point of interest, not recommending it be done. I had a Studebaker done this way with a sbc, and it got the job done, I'll say that for it.

Don

Vacuum wipers don't care about the voltage.The oil and heat guages are mechanical, radio doesn't work I'm thinking about a 12 volt battery hooked to the starter only and leave the 6 volt system(with charging) intact..I would have to charge that 12 volt battery periodically..I picked up a 10SI alternator that looks like it might bolt right into the generator bracket but the car uses a 3/4" wide V belt.I would 3 wire it cause this old thing might make enoough RPMS to excite the alternator..lol Just trying to evaluate the options.Thanks for the opinions

Originally Posted by Itoldyouso

I'm not recommending this method, but it does work...........to a degree. Back in the day when we would just do stuff to get it done and you couldn't buy all the fancy stuff we have today, we would make up our own 6 volt/12 volt system by installing a 12 volt battery, then running a stainless steel self tapping screw through the top of the battery exactly mid way between the positive and negative posts. Each cell is 2 volts, so the typical 12 volt battery has 6 of them, and if you tap down into the cells half way across you will get a 6 volt tap from which you can power stuff that can't be changed to 12 volt ones, like the wiper motor, etc.

The problem is, this is pretty much considered shade tree by todays standards and it also shortens the life of the battery somewhat as you are overworking 1/2 of the battery. We used to do this trick when we were swapping a newer 12 volt engine into an older 6 volt car.

Thank God we came out of those dark ages of car building, and I am only mentioning this as a point of interest, not recommending it be done. I had a Studebaker done this way with a sbc, and it got the job done, I'll say that for it.

Don

Don....You're brilliant...You just gave me a hell of an idea....I'll get another 6 Volt battery, series wire the starter and alternator, then run the rest of the car on 6 volts and the alternator can keep both charged...Why wouldn't that work??

Originally Posted by Daffy427

....I'll get another 6 Volt battery, series wire the starter and alternator, then run the rest of the car on 6 volts and the alternator can keep both charged...Why wouldn't that work??

There are some minor issues involved with doing that. The two batteries will discharge unevenly and then charge unevenly. It's not a huge deal, you will just need to charge the two 6v batteries individually occasionally to keep them even.

For whatever reason, running two 6v batteries in series and charging with a 12v alternator just doesn't keep them evenly charged, unless they are also discharged evenly. I know this from experience on a friends car where we did a 12v conversion, but ran two 6v's so we could tap off the middle to power vintage spotlights and fog lights that we couldn't get 12v bulbs for. The 6v battery that was running the fogs and spots would get low on voltage and would not come back unless you put a battery charger on it.

No big deal, just a little more routine maintenance.

Personally, I would go ahead and convert the whole car to 12v, including converting the starter to 12v. But that's just me, I like to keep things simple.

The starter works great on 12 volts

I am looking into upgrading my 40 Graham from 6 to 12 volts and have been doing some planning as to what parts I will need for the conversion. I have two questions.
First, the Graham's electrical system is positive ground and I would prefer to switch it over to a 12 volt negative ground. What needs to be done to make this switch.
Second, the headlight system uses a bulb and cannot be easily changed to sealed beam. The bulbs used are marked as GE 2320 which appears to be the model number (they also have printed on them "32 & 320 6 - 8v.) Does anyone know if there is a modern 12volt bulb replacement or is there a conversion to halogen bulbs and where would such replacements be available.

I seem to recall a similar discussion here in the past, where we were told about a 6v/12v battery that is made that way for what you are talking about. I believe they are still for sale . I can't seem to find one, but I know I've seen them!

Check your electrical supply shop for a "series/parallel switch". This allows two 6v batteries to be momentarily be switched to 12v for starting. If you just hook the starter to the 12v outlet post, the gauges won't work when the starter is operating, but they won't fry, either.

Hmm. Just googling and the only S/P switches I can find are 12/24 volt, for like old Mack trucks. Maybe the 6/12 volt ones are museum pieces!
Anyway, the two 6v battery trick still works. Use a 12v generator or alternator and run the starter on 12v, everything else on 6v. To even out the wear and tear on the one battery, swap them around every now and then. Or get a Mor-Drop resistor, if you can find one of them outside a museum!!! I used to have a few if them, hope one turns up for my "54 Bel Aire.

I found a dealer on ebay who carries all kinds of resistors for 12 volt conversions..I think I'm gonna ebay this Pontiac like it is as I'm buying another project house that's gonna keep me pretty busy and I need the garage space..Ya just can't fix them all..I need to thin the heard as much as I hate to..