Running 6 volt gas gauge on 12 volts?

[55 Fargo]

I have used 12 volts with out any voltage reducer to test my new sender and fuel gauge a number of times. I have this new sender in the tank now, but am waiting for zener diodes to arrive. 

Can I run this gauge safely on 12 volts until then? This gauge is a 1 wire from sender to gauge, so  not like the 2 wire sender that has a built in voltage regulator in the gauge to regulate voltage.

I do not see why the gauge would care is it has 6 or 12 volts? Unless the current draw heats it up too much, I did run the truck for at least 5 minutes earlier, it didn't do anything to the gauge...I have read that some run there 6 volt gas gauges for years on 12 volts and no voltage reducers, and some try it once and burn up the gauge....

 

[TodFitch]

. . . Unless the current draw heats it up too much, I did run the truck for at least 5 minutes earlier, it didn't do anything to the gauge...I have read that some run there 6 volt gas gauges for years on 12 volts and no voltage reducers, and some try it once and burn up the gauge....

 

That would be my worry. Seems like you could just measure the resistance from the power input to the gauge to ground and then get a resistor from radio shack that is the same and wire that in series. Probably doesn't need to be real high wattage but once you measure the resistance and know that you are dropping about 6v you can calculate the wattage. A few minutes worth of measuring and a quick trip to the local equivalent of Radio Shack and you are safe.

[Don Coatney]

Best hurry to find a Radio Shack epically in the Bay Area. 

 

http://www.bizjournals.com/sanfrancisco/blog/real-estate/2015/03/radioshack-rshcq-closures-real-estate.html

[TodFitch]

Best hurry to find a Radio Shack epically in the Bay Area. 

 

http://www.bizjournals.com/sanfrancisco/blog/real-estate/2015/03/radioshack-rshcq-closures-real-estate.html

Turns out the one local to me is staying open. Also turns out that I'd probably go to Fry's Electronics anyway but I think that is a regional chain/phenomena so I didn't mention it.

[1941Rick]

Just wire a small dash light bulb in series into the power wire coming to the gauge...this will slow down the sweep of the needle......been like that on my car for years with no problems.....

Edited March 14, 2015 by 1941Rick

[55 Fargo]

Just wire a small dash light bulb in series into the power wire coming to the gauge...this will slow down the sweep of the needle......been like that on my car for years with no problems.....

Hi Rick, so you are running a 1 wire gas gauge with full 12 volts? I know what you are saying with the bulb thing.

The gas gauge is working with the new sender, and 12 volts, it reads a little high on empty, and a little low on full, could be the result of using 12 volts on the 6 volt gauge causing an amp draw change, which creates a change with resistance from the sender unit, not sure if that is correct or not....

.

[55 Fargo]

Pulled Fargo out of the garage, gauge on 12 volts is reading a bit high, and needle bouncy when gas is sloshing around, very sensitive. I am thinking is this a result of 12 volts, creating faster more pronounced fluctuation.....LOL lots of fun, 

[MBF]

I don't think that gauge is going to like 12 volts w/o the correct resistor for very long.   Don't ask me how I know!

[55 Fargo]

I don't think that gauge is going to like 12 volts w/o the correct resistor for very long.   Don't ask me how I know!

Yup, not running it until my zener diodes arrive, it will then have 6 volts to the gauge, and hopefully work well....

[timkingsbury]

I have used 12 volts with out any voltage reducer to test my new sender and fuel gauge a number of times. I have this new sender in the tank now, but am waiting for zener diodes to arrive. 

Can I run this gauge safely on 12 volts until then? This gauge is a 1 wire from sender to gauge, so  not like the 2 wire sender that has a built in voltage regulator in the gauge to regulate voltage.

I do not see why the gauge would care is it has 6 or 12 volts? Unless the current draw heats it up too much, I did run the truck for at least 5 minutes earlier, it didn't do anything to the gauge...I have read that some run there 6 volt gas gauges for years on 12 volts and no voltage reducers, and some try it once and burn up the gauge....

If it is a 6 volt gauge, disconnect it asap. It will burn it out without the resistor in line. The 1955 fargo should have been 12 volts though. That is the start of 12 volts for the Canadian based pickup Dodge/Fargo.  My 1954 is 6 volt, and my 1955 is 12 volt.

 

But if it was a 6 volt system you definitely don't want to run it on 12 volts..  It may give you the illusion it is working, just not quite reading correctly, and then it

will cease to function. It doesn't care about the polarity, but it does the voltage increase.

[55 Fargo]

If it is a 6 volt gauge, disconnect it asap. It will burn it out without the resistor in line. The 1955 fargo should have been 12 volts though. That is the start of 12 volts for the Canadian based pickup Dodge/Fargo.  My 1954 is 6 volt, and my 1955 is 12 volt.

 

But if it was a 6 volt system you definitely don't want to run it on 12 volts..  It may give you the illusion it is working, just not quite reading correctly, and then it

will cease to function. It doesn't care about the polarity, but it does the voltage increase.

Thanx Tim, not sure if it was from a Fargo, or Dodge had a few cabs and parts, and do not want to burn it up. I have had the gauge power wire on it for years but had the sender wire off, so no circuit. It is disconnected again now.thanx

[timkingsbury]

Thanx Tim, not sure if it was from a Fargo, or Dodge had a few cabs and parts, and do not want to burn it up. I have had the gauge power wire on it for years but had the sender wire off, so no circuit. It is disconnected again now.thanx

I hear you.. it is like my place..   As you know it doesn't matter Dodge or Fargo in terms of truck stuff..  Chrysler flipped to 12 volt in 1953 up here.. but the trucks not till 1955. But if it maybe came out of an earlier one then it could easy be 6 volts..  Its happened to me I can tell you.. I thought I was using stuff out of a 1957 powerwagon  at one point and it turned out to be pre-1955..  There is a way of telling which is which, but it would require some investigation as I don't know. My "is this 12 volt or 6 volt" source for my stuff is no longer with us..   You have a resistor coming I think you said right ?

[55 Fargo]

I hear you.. it is like my place..   As you know it doesn't matter Dodge or Fargo in terms of truck stuff..  Chrysler flipped to 12 volt in 1953 up here.. but the trucks not till 1955. But if it maybe came out of an earlier one then it could easy be 6 volts..  Its happened to me I can tell you.. I thought I was using stuff out of a 1957 powerwagon  at one point and it turned out to be pre-1955..  There is a way of telling which is which, but it would require some investigation as I don't know. My "is this 12 volt or 6 volt" source for my stuff is no longer with us..   You have a resistor coming I think you said right ?

Hey Tim, yes the resistor is on the way. now the 2 parts trucks I had, had 6 volt starters and gennys, and were both 1955s, so they did not get switched over to 12 volts by the look of things.

I figure my gauge is 6 volt, as it was in a cluster where the amp gauge is 50, so 6 volts, I have never had any of the 30 amp gauges that came later for 12 volt systems....

[55 Fargo]

Mission accomplished, installed zener diode runtz, gas tank sender with about 2 gallons or so of gas displayed 65 ohms from the sender unit.

The gas gauge with power is displaying about 1/8th of as tank, close enough for me, will fill the tank up more and see how it goes. This was a $3.00 fix....