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Old 05-07-2007, 01:02 PM
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6 To 12 Volt Conversion


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Old 05-07-2007, 02:31 PM
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Here are some good sites for reference.


Some 6 volt cars had a positive ground. The 12 volt system must be negative ground.
The 10SI alt has an internal regulator. You may be able to use one of the old wires for an idiot light. Otherwise the only wire you need is the heavy one running to the battery.

The BATTERY gauge is probably an ammeter. You will not be able to (easily)use it. It won't have the capacity to safely handle the charging current output of the new alternator.
Use a voltmeter.

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Old 05-07-2007, 05:37 PM
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Doc here,

First, We need to know What car your dealing with. Next would be is it Positive or Negative ground.

You Just can't toss a 12 volt battery and 12 SI charging system in and call it good..you will damage a lot of stuff..maybe start a fire.

To upgrade the system you need to change:
  • ALL lamps..(Head, tail, turn, brake, dome, glove, Trunk, hood, Dash dimmers, ANY bulbs you now have)
  • Flasher unit
  • Hazard Flasher (if used)
  • Heater Motor and speed control.
  • Wiper Motor and speed control (If Electric), If vacuum, now is a good time to install a reserve canister to stop "On Throttle" drop outs.
  • Coil.
  • Horn Relay.
  • Horns.
  • ANY Existing Relays.
  • Starter Solenoid.
  • Starter, While it will run at 125% of rated Value, it will shorten it's useful life..AND you have to replace the solenoid anyway.
  • Gauges, Any Electrical gauges you may have (most likely Fuel only) should be upgraded, OR run on an Instrument regulator, (12 to 6 volts)
  • RADIO, May be problematic , especially in a Positive ground Vehicle, the best course is a DC to DC Converter. Provides enough current to run a Tube Radio, AND is Isolated From the car buss system..

Your Harness WILL support the 12 volt system, as far as Wire Size..BUT if it is Fray, Molested with tons of Butt Splices, Cotton clad and gas or oil soaked, You may want to consider s New Kit..Cotton Clad Gas Soaked Wire CAN act more like a Firecracker Fuse..IT will support a Flame. So Inspect your Harness Well before going on.

You will need to install Fuse links For the Main Fuse Buss, and Alternator output wire. Without them you could have a fire.

Equally as important, Is a Good Ground Buss System:

For your Ground Buss, Set it up as follows:

BE sure First, You have A 4 gauge Cable (for stock battery location, OR , 0/0 or 0/1 Cable for a trunk location) from the battery, to any handy bolt at or NEAR the starter on the block .

Using a short run to something like a seat belt bolt, or body bolt just adds resistance, the body is insulated..(has road paint and sits on rubber mounts) this , makes for a "Poor or no" Bonding situation..
  • that makes resistance..
  • Resistance makes Heat..
  • heat melts things and further insulates the bond,
  • which makes more heat..and so on..until you no longer have a good bond..

To install a proper ground buss system, This MUST be done:
  • 1 ) Run a properly gauged (0/0 or 0/1) Ground cable from the battery in the trunk, Or A 4 Gauge cable for a stock located battery, to any handy bolt at or near the starter on the block. From that same bolt get a 4 gauge Battery cable at the parts store, that has two 3/8 ring terminals on each end and attach it there and to the Frame. Make this run as short as possible.

  • 2 ) Next get some 10 gauge wire and ring terminals, run two wires from your bolt on the block, to the Firewall, Burnish off all the paint, grease or oil or dirt from the area, Install a sheetmetal or Self Drilling Tech screw using a star washer as well as a lock washer.. and the other 10 gauge wire to the Alternator ground lug, bracket or mount bolt and attach with star and lock washers.
  • 3 ) Next get some Wire Braid, (expensive! about $10 for 5 - 6 inch pieces! ) Check Radio Shack for this, OR cheaper yet, get some RG 8 Coax cable, about 10 feet. Should run you about 15 cents a foot.

  • 1 ) carefully Slit the insulation from the cable with a Talaban Boarding pass (box knife) .

  • 2 ) Peel away the insulation until you just have the center dielectric and braid left, then carefully press the ends of the coax cable BRAID together like a Chinese "Finger puzzle"

  • 3 ) Slide the dielectric and center conductor out. remove it and toss it..

  • 4 ) On a work bench, Flatten the Braided shield out, use a round weight like a full paint can to roll over it.

This will be your braid cable, just Cut to smaller length's as needed, and tuck the cut ends into a crimp terminal and crimp the ends on..

IF you can Solder, Tin the ends before you tuck the ends of the cable into the terminals, then Tin the barrel of the terminals, then insert the cable and crimp..

Then heat the terminal and braid, feed some solder into the opposite end as the heat is being applied, let it melt and FLOW or WICK toward the heat..until the terminal barrel is filled and is smooth and shiny..

that is a good joint..gray and rough is a "Cold Joint" and you'll have to start over..
  • 4 ) NEXT, install braid from the radiator support to the frame, Fenderwells to frame , hood to firewall, Doors to door posts, gas flap to body, tailgate / Trunk to body. Install a cable or Braid From the Fuel tank Ground lug where the sender, Fuel line is to the frame..burnish the frame, use star washers and sheetmetal or Tech (self Drilling screws) on the frame.

  • 5 ) At each point the wire is grounded, Burnish ALL the paint and grease off to bare metal. Use a proper star-washer and lock. Use sheetmetal or Tech screws where no screws are available.

It sounds like a lot of work, but after you assemble all the parts, it's only a few hours to do..and you'll end up with a system that will work reliably for many years to come..and can eliminate that from your troubleshooting list.

Remember: GROUND is the other Half of your 12 volt circuit AND is equally as important as having POWER to the device!

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Old 05-07-2007, 11:13 PM
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Thanks for the info... I'm working on a 40 Ford, keeping the flathead. I have changed the starter relay, added extra ground wires one from the bell housing to battery, second from the bell housing to the frame. and the battery is grounded to the cab. I have changed the motor on teh heater to 12 volts, and the heater switch also. I have changed all the bulbs in the tail light head lights dash lights, and the turn signal indicator. I have not changed the high beam light as of yet but will. I have put a voltage reducer in line with the gauges... I'm still not sure what to do with the battery gauge, as of now its unhooked. I'm trying to use the 6 volt harness as its in good shape. so the wires going to the regulator still also has me a little confused. Sorry for the lack of infromation the forst time. As of yet a 12 volt battery has not touch the car..
So what do I do to make the battery gauge work on 12 volt, and the wires coming from the regulator?
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Old 05-07-2007, 11:43 PM
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Doc here,

The Gauge is probably -30 ~ 0 ~ +30 , Your Delco is a 60 amp Alternator, the gauge is probably not going to work..You Need a -60 ~ 0 ~ +60 Gauge (or shunt) at FULL load.

At any rate, If the car was Pos. Ground, Reverse the leads at the gauge and it will indicate in the right direction.

IF you should see a full load at the gauge you'll probably peg it, damage it or burn out the shunt..(which might leave you without power).

I'd Disconnect the gauge, and install a Volt meter, much simpler to install, Safer to use, and reports the same information. You don't have high current wires to short under the dash.

Short of that you may consider a Shunt out of a 12 volt gauge, and multiply the numbers by 2....but that's not a stellar way to go.

All the wires from the regulator will go away EXCEPT for the REDS at the Batt Terminal. Just connect these together (they power other parts of the car) and remove them from the regulator, then remove the regulator.

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