6 volt gauges

[brent stella]

I am putting a different motor in my boat and it has a 12v generator. The problem is that my boat has really nice original 6v gauges in it. Will there be a problem if I hook this motor up to these gauges? If so, what can I do to fix it. Is there some kind of step down voltage converter I could hook up the guages?

[Gresham CA]

I believe Stewart Warner has a Retro line of gauges.

[hikingchrs]

Yes there will be a problem... the needle will move 2x farther than what it should... probly burn out as well. Radio Shack sells a device that converts 12v to 6v. 12v side to engine battery 6v side to some sort of distribution block with fuses. wire 6v devices to this... make sure you lable wires well so that you or someone who works on your boat does not terminate wires in the wrong spot...
Chris

[Dan McCosh]

It should be possible to use a resistor to reduce the voltage to 6V. The guage manufacturer should be able to help.

[ahp]

If you have a multimeter, put it on the ohms scale and measure the resistance of the 6V meter. Buy a resistor equal to the value that you measured and put in series with the 6V meter and now you have a 12V meter.

[hikingchrs]

If you use a resistor make sure it is rated for the total load I would use one for each gauge. I have done this for a heater fan for my Jeep the resistors will get hot. maybe hot enouph to burn skin, or scorch wood depending on how much the gauges draw.
Chris

[Canoeyawl]

Gauges/sending units are essentially switches and are very forgiving about voltage changes. (12V has only half the current) Some are not forgiving about polarity changes and you may find that the 6V system was positive ground and the 12V is negative and they may function backwards. This only matters with the ammeter usually. I suspect you will be able to connect everything up the way it was designed and reverse the ammeter connections if required. I have switched numerous old Fords etc. (hot rods!) to modern engines; no problems, all gauges worked fine, even the fuel gauge...A cautious trial of each one will prove this.
edited to add; lightbulbs and motors must be either changed or the correct resistor added or these will be ruined!

[ 04-18-2005, 11:41 AM: Message edited by: Canoeyawl ]

[pcford]

This is very common. Resistors are often added. A good auto electric shop can sell you appropriate resistors.

Perhaps the most easy thing to do is contact an instrument restorer. I can recommend a couple if you contact me.

[Carl Simmons]

What gauges are involved? Tach, Temp, volts, amps, etc?

[brent stella]

They are Temp, Tach, Amp, Fuel, Oil, Clock, and Speedo. All are Stewert Warner. Does anyone know the number of the resistor that I need from Radio Shack?

[brent stella]

I found some Info...

Instrumentation
Time for decisions again! Do you want to retain your original quages? Or do you want to upgrade your monitoring devices? Do you even have guages? Do you want guages?
If upgrading, do you want to retrofit later model "factory" guages from some donor vehicle? Or do you want to look to the aftermarket?

Original Instrumentation
If your vehicle is only equipped with idiot lights, you can simply change the bulbs and be done with it.
If you have guages, you can utilize a dropping resistor in the feed line to the instrument cluster (same warning as with the ignition ballast, mount it away from anything meltable).
Here are a couple possible pre-made devices that may make things easier;

AC Delco U1745
"Voltage Reducer. Reduces 12 volts to 6 volts. 1.5 ohm resistance for 4 amp maximum load. Permits use of regular 6 volt accessories on 12 volt systems. Mounts through 7/16" dia. hole. Includes clamp on bracket."
AC Delco F610 and F611
Ford:C9AZ-10804A and D1AZ-10804A
From what *I* can figure this is the instrument cluster reducer for the below mentioned Mustang II instrument cluster.
I can neither confirm or deny this products proper use. If you know this products function please e-mail me the information and I will update this info.
"Regulated Voltage Reducer".
One used per guage. Spotted in the JC Witney catalog.
A point of interest for those who wish to retain a 6 volt system (or, utilize their original 6v guages in a 12v environment), AND upgrade their guages somewhat, look to the Ford Mustang II (197?-1978). The Mustang II utilized 6 volt guages! Mounted to the back of a Mustang II instrument cluster is a voltage limiter (from what I gather, it operates like mehcanical voltage regulators using points.) and in the Mustang II, each guage has an 8.5 ohm resistor for each circuit. Check out a wiring diagram for the Mustang II for reference and ideas to incorporate into your system.

Alternately you can look to later model 12 volt instrument clusters for donor guages/sending units. Again, you'll need to scare up wiring diagrams for the donor vehicle to properly wire in your new guages.