12 Volt Conversion Questions

[John Burke]

My 49 Dodge project got a SBC for a motor..My question concerns polarity. Since I will now be running negative ground, nwhat do i do about the positive ground stuff in the car, namely the electric wipers?...John

[Lou Earle]

To my knowledge motors will work either way . I run a 6 volt heater in my 48 ford it was pos ground but it - the car is now 12 v and I run the pos thru a reducer.

The radio will not work. Also the 6 volt pos ground generator does not adapt thru the regulator.

I imagine no problems except radio

Lou

[randroid]

So far as WW motors are concerned, if you reverse the polarity the motor should run in reverse. Thing is, with WW how would you know? Lights not only don't give a fetid pair of Dingo's kidneys what the polarity might be, it matters not a whit to them if it's AC or DC. There were discussions lately on this topic concerning fuel and amp gauges and what my meager memory brings to this point is that you have few cares along those lines. Since the temp gauge is mechanical and regularly snubs electrical circuits as soft and easily broken you should pretty much have the rest of it covered.

Should you ever have another question please don't hesitate to ask. I am always eager to share my opinions and advice regardless of how erroneous, misleading, or purely hypocriphal they might be.

Merry Christmas to all. I had fun writing this.

-Randy

[greg g]

Randy. Bit too much holiday nog????? I might think the motor WW motor would confuse its parking place withthe wires reversed but that is only a guess.

[Plymouthy Adams]

these are not permanent magnet DC motors...therefore they care not which is pos and which is neg...

[PatS....]

"don't give a fetid pair of Dingo's kidneys what the polarity might be"

Now THAT is one unique saying...lol!!!

[Guest Howiesnevets]

Two six volt batteries can be wired in series to get 12 volt. Has anyone tried taping into the cable between the two batteries to run 6 volt accessories? Any thoughts if that would work to run both 6 and 12 volt accessories on the same system??

[Merle Coggins]

Two six volt batteries can be wired in series to get 12 volt. Has anyone tried taping into the cable between the two batteries to run 6 volt accessories? Any thoughts if that would work to run both 6 and 12 volt accessories on the same system??

It would work, but you'll have charging problems with the batteries. The battery that's not connected to your accessories will get overcharged, reducing it's life. I've seen it happen many times on 24v systems (2-12v batteries) where they run a radio off of one battery.

Just my opinion from experience,

Merle

[Guest Nile Limbaugh]

Back in the days of kerosene powered television (the 50's) we used to run 6 volt accessories from 12 volt batteries by running a wood or sheet metal screw into the battery at the midpoint thus (after a few tries to make the connection) tapping off juice from the first half of the battery. The reason was that you could still get a 6v radio (for instance) cheaper at the junkyard. Using this parallel it's possible to install two six volt batteries in series to run either 6 or 12 volt stuff. But you would need a 12v charging system for this to work.

[Guest mikeys toy]

My wipers won't work with the 12v neg ground, the parking "points" kick in and it shorts

[48mirage]

Merle,

I understand what you are saying about the overcharging of the lesser used battery. I am thinking that in this application it may be the other way around. Let me explain. In your industrial setting the inner battery supplied the accessory and the combined batteries served the needs of the equipment.

In the scenario put forth the inner battery has the more constant draw servicing the needs of the car and the outer battery is servicing the accesories. It is used less and if the 12 volt charging system is trying to maintain 12 volts total, it appears to me the outside battery is the one that is going to get cooked. Same problem different result.

Now here is one that I can't figure out. The link takes you to a guy who says he put a dual electrical system in his car. 6 volt positive ground with generator to serve the needs of the car and a 12 volt negative ground to supply ignition, fuel pump, accessories. I can't get my head around it and he has not responded to my email. I would like some opinions on this.

http://classichemi.com/index53.shtml

[Don Coatney]

I can't get my head around it and he has not responded to my email. I would like some opinions on this.

Appears the guy did a pretty good job of splaining how he did the dual voltage setup. The six volt positive ground used the frame and body for ground. The twelve volt negative ground uses the frame and body for ground. The circuit is not complete until a connection is made back to the source (battery in this case). George Asche also is running a dual voltage system in his car. I believe Hotlanta Richies brother Bobby is also running a dual voltage setup for his air conditioned P-15.

[48mirage]

Here is where I get confused. When the thing is running, why isn't the 6 volt positive ground interfering with the 12 volt negative ground. I feel a little slow in this, but I keep coming up with 6volts potential when you use both systems at the same time.

[Don Coatney]

The frame and body are common to both voltage systems. But the circuit is not complete until a connection is made to either battery.

[Merle Coggins]

Merle,

I understand what you are saying about the overcharging of the lesser used battery. I am thinking that in this application it may be the other way around. Let me explain. In your industrial setting the inner battery supplied the accessory and the combined batteries served the needs of the equipment.

In the scenario put forth the inner battery has the more constant draw servicing the needs of the car and the outer battery is servicing the accesories. It is used less and if the 12 volt charging system is trying to maintain 12 volts total, it appears to me the outside battery is the one that is going to get cooked. Same problem different result.

Now here is one that I can't figure out. The link takes you to a guy who says he put a dual electrical system in his car. 6 volt positive ground with generator to serve the needs of the car and a 12 volt negative ground to supply ignition, fuel pump, accessories. I can't get my head around it and he has not responded to my email. I would like some opinions on this.

http://classichemi.com/index53.shtml

You're close. But actually it is exactly the same as what I refered to. Whether it's a series 12v or 24v system, you are doing the same thing. Using your analogy, "inner battery has the more constant draw servicing the needs of the car and the outer battery is servicing the accesories", actually both batteries have to work together to make 12 volts but one of the batteries is also called on for the 6 volt system. So this battery is doing double duty and the charging system charges accordingly which overcharges the other battery.

If you are dead set on using this type of system, I would recommend a Bettery Equalizer. These are designed for this use and will keep the batteries charged equally. I'm not sure where to get one for 6/12v systems, but I have seen them for 12/24v systems.

[48mirage]

Not dead set on anything, but looking at all the options. I'm currently trying to figure out what drawbacks there may be if any running the dual battery charging system I pointed to in my earlier post.

[BobT-47P15]

George has so much stuff under the hood of that old DeSoto roadster, it almost looks like a late model vehicle......you can hardly see the actual engine. IT would be interesting to know just what some of those knobs, gauges and gee-gaws on his dash do. He's a pretty darn inventive fellow.

[Tim Frank]

If the "positive ground" item has two wires, you should simply be able to switch the wires as long as the extra voltage is not a factor.

[james curl]

I have an older copy of J C Whitney catalog no. 602C from August 31, 1997, in the getting started & charged up sectgion page 174 they list a Dual-Voltage Starting Switch which hooks two six volt batteries in series. The switch is called a series-parallel switch. When starting switches to twelve volts then back to six after starting. The switch sold for $59.95 in 1997, I do not have a current copy of their catalog to see if they still list it. I looked into this twenty years ago when I was having starting troubles. But with switch, new battery, underfender drop out battery box, and wiring would cost over $100.00 and new 00 cables from same catalog same page were from $7.00 to $20.00 for 12" to 72" length. With 00 cables have never had trouble starting and I run my timing just below the ping threshold and when heat soaked hits pretty hard never fails to start on about the second or third revolution.