Electrical: Converted 6V generator to 12V

[garyash]

For my Indy car replica project, I want to have the car running with 12 volt electricals - if only to be able to charge a cell phone. I'm using a 1937 President 8 engine that had 6 volt positive ground. The generator that came with the engine had been in the mud for a while, so I couldn't even turn the shaft when I got it. I cleaned out as much crud as I could, got it to turn, and oiled the bearings. These generators have a rear extension for the shaft that drives the water pump, which is mounted on the side of the engine, so I couldn't just grab any old 12V generator and use it.

Luna Industries in Tuscson, AZ (www.lunaindustriesinc.com) took the old unit, rewound the armature and replaced the coils, converting it to 12 volts negative ground. I'm still a long way from getting an engine to run, but I am happy with the conversion job.

Here's the generator after I cleaned it up a bit:


Here's the generator after the conversion:

[JohnM15]

Gary, that pretty cool. I didn't convert to 12V but added a 6V to 12V to dive the cigar lighter for accessories such as my Droid. If I want to add a radio/stereo then I'll have the 12 volts...

[jclary]

Gary, that pretty cool. I didn't convert to 12V but added a 6V to 12V to dive the cigar lighter for accessories such as my Droid. If I want to add a radio/stereo then I'll have the 12 volts...

How 'bout 'splaining to a poor schlub like me how you handle two separate generators on one engine. Additionally, how you wire up a 6 volt system with a positive chassis ground and insulate the 12 volt negative ground from wanting to do battle with the 6 volt system. I might want to try something like that, but there are some hazards I don't have figured out.

[PlainBrownR2]

I have one of those Archer 6 to 12V converter boxes on the 2r5. It wasn't hard to do, the terminals were labelled on the box if I recall. The 6V was wired positive to positive and negative to negative. However, on the 12V side, it was a negative ground, so to pull that off, which was only being wired to the cigar lighter at the time, I wired it as it would work on a 12V negative ground vehicle. The thing I had to do though was insulate the external casing of the cigar lighter, which I did with electrical tape, and then the tip I believe was grounded to the body. Plugged my phone in, and the while the truck was running, it started charging the battery from a 6V system.

[jclary]

I have one of those Archer 6 to 12V converter boxes on the 2r5. It wasn't hard to do, the terminals were labelled on the box if I recall. The 6V was wired positive to positive and negative to negative. However, on the 12V side, it was a negative ground, so to pull that off, which was only being wired to the cigar lighter at the time, I wired it as it would work on a 12V negative ground vehicle. The thing I had to do though was insulate the external casing of the cigar lighter, which I did with electrical tape, and then the tip I believe was grounded to the body. Plugged my phone in, and the while the truck was running, it started charging the battery from a 6V system.

Ok, so what you have (if I understand this correctly) is a "step up transformer" that will provide a twelve volt circuit with a dedicated ground (not chassis ground). That makes sense as long as you have a device that don't exceed the current draw. I guess the trick is to keep the devices well insulated from each other.

[PlainBrownR2]

That's the logic of it. Negative goes to negative, and positive goes to positive, and neither polarity should cross or the box will probably short out. The old Radio Shack style Archer boxes were not much more than I think either a step up transformer or a transistor circuit. I got it at a hamfest for about 5 bucks, and I thought it was more than convenient for what I needed it for. It's maximum is about 3-5 amps, and my cellphone's output is down in the milliamp range, but if I want something in the range of a radio, speakers, or aircraft lamps in the truck, the whole vehicle will need to be converted to 12V.

[JohnM15]

I used a different converter box. The one I used is capable to output 6AMPS @ 12V. The unit is basically a inverter since you cannot use a transformer to transform DC. In an inverter, the incoming DC is converter to AC by way of an oscillator. The oscillator then drive a transformer that steps up the voltage. The AC coming from the transformer is then converted to DC using rectifiers and filters. Usually there is also some form of regulation to keep the output voltage at 12V regardless of load. As I said, mine just drives a cigar lighter for powering accessories such as my Droid. The 8AMPS cannot drive an actual cigar lighter though. If I choose to add a radio then the 12V will come in handy. The unit I used also has a control input that turns on the unit when the ignition is in accessory or ignition. This is so it does not drain the battery when not in use. This one also has a "always hot" output to maintain memory in radio and such. This output draws very little current, in the order of a few milliamps.

Here is a link to a post on my blog that shows the block diagram I made when I rewired the truck:

http://studem15a-20.blogspot.com/b/p...4191&type=POST

[DEEPNHOCK]

I'm a little surprised you didn't just have it built with an alternator inside, and really up the efficiency...
Here's one company that does that...

http://www.gener-nator.com/

[JohnM15]

I used a different converter box. The one I used is capable to output 6AMPS @ 12V. The unit is basically a inverter since you cannot use a transformer to transform DC. In an inverter, the incoming DC is converter to AC by way of an oscillator. The oscillator then drive a transformer that steps up the voltage. The AC coming from the transformer is then converted to DC using rectifiers and filters. Usually there is also some form of regulation to keep the output voltage at 12V regardless of load. As I said, mine just drives a cigar lighter for powering accessories such as my Droid. The 8AMPS cannot drive an actual cigar lighter though. If I choose to add a radio then the 12V will come in handy. The unit I used also has a control input that turns on the unit when the ignition is in accessory or ignition. This is so it does not drain the battery when not in use. This one also has a "always hot" output to maintain memory in radio and such. This output draws very little current, in the order of a few milliamps.

Here is a link to a post on my blog that shows the block diagram I made when I rewired the truck:

http://studem15a-20.blogspot.com/b/p...4191&type=POST

Here is a link to the one I purchased:

http://www.6to12volt.com/

[JohnM15]

Deepnhock, that's awesome! That makes 6 volts systems even better, no need to switch to 12 volt (almost...) Geez, when my generator blows I'll go with that.

[JohnM15]

Since the converter I used has a common ground between input and output there is no need to isolate grounds, just don't connect the 12V to the 6V.

[jclary]

I'm a little surprised you didn't just have it built with an alternator inside, and really up the efficiency...
Here's one company that does that...
http://www.gener-nator.com/

Thanks Jeff for posting this. This happens to be another in a long list of things I thought that I was first to conjure up in my mind. It is just another humbling reminder that by the time I think of a good idea...someone else has already done it!

I clicked on his testimonial page and saw where someone in Texas, named Bill, has bought one for a Studebaker Truck. If anyone here on the forum has bought one, how about giving us a ball park price so we can attempt to not gulp so loudly when calling to place an order.

[JohnM15]

Happens to all of us... when the hula-hoop came out I dreamed up the weed eater. I attached a blower motor to a broom handle and attached a wire to the shaft. It worked great but I was just a kid, maybe 10 or so...

[garyash]

Jeff: The Gener-nator is a great idea, but he can't convert generators with a shaft coming out the back end of the housing, like my 1937 unit with a water pump drive or early Corvettes with the tach drive out the back. Too bad!

On the other hand, in the Indy car, there won't be a radio or much else taking current so a 30-35 amp 12 volt generator will be more than enough. Ignition and gas gauge will be about it. The temperature and oil pressure will be mechanical. While I plan to mount enough headlights and tail lights to be legal, on removable brackets, I don't think I'll be doing much night driving. But, then, like tonight is a warm summer night, it might be fun to blow by some people on the road in the Indy car late some night with the 4-inch open exhaust pipe making crackling noises...

[JohnM15]

"4-inch open exhaust pipe making crackling noises... " Nice! There are times where some sound pollution is a good thing!!! Sorry that your post meandered...