6v to 12v conversion

Forward Look Forum

  1. paul tracy

    paul tracy New Member

    Messages:
    5
    Likes Received:
    1
    Joined:
    Apr 4, 2021
    Location:
    sun city Arizona
    our 55 has had a 12v generator and starter installed by former owner, with negitive ground 12v battery. runs fine. Is there a way to put drop downs in so we dont burn up the gauges and radio? Has anyone done this?
     
  2. Big_John

    Big_John Illegitimi non carborundum FCBO Gold Member

    Messages:
    14,091
    Likes Received:
    8798
    Joined:
    May 21, 2013
    Location:
    Marcellus, NY
    • Agree Agree x 2
    • Thanks! Thanks! x 1
  3. Davea Lux

    Davea Lux Old Man with a Hat FCBO Gold Member

    Messages:
    8,335
    Likes Received:
    1999
    Joined:
    Mar 27, 2017
    Location:
    Cornelius Or
    The red neck solution was to use a ballast resistor in the circuit that fed the gauge setup. Cheap way to avoid and expensive power convertor. It works well enough to get the car down the road. A ballast resistor can not handle the load for a heater motor, lights, wiper motor or radio, you would need a power convertor for that or you would need to convert those items to 12v units.

    Dave
     
  4. Big_John

    Big_John Illegitimi non carborundum FCBO Gold Member

    Messages:
    14,091
    Likes Received:
    8798
    Joined:
    May 21, 2013
    Location:
    Marcellus, NY
    Here's the problem with using a resistor...

    Ohms law R=V/I

    Resistance = Voltage/Current

    In this case, you want to drop down 6 volts.

    R=6/I

    Now if you knew what how much current your radio drew, you can figure this out, but lets say it draws 3 amps.

    R=6/3

    R=2 Ohms

    You would need a 2 ohm resistor to drop a radio that draws 3 amps down to 6 volts.

    Now, let's say we use a ballast resistor with the 3 amp radio. Typical ballast resistor resistance is 1.2 ohms.

    1.2=V/3

    V=3.6

    You have a 12 volts and now you subtract 3.6.

    12-3.6= 8.4 volts.

    So your 6 volt, 3 amp radio would have 8.4 volts running into it.

    I have no idea how much current a '55 radio draws. I remember reading 1/2 amp per tube, but I think that was for a later 12 volt tube radio. Might be a half dozen tubes, so I may not be far off with 3 amps, but don't bet the farm (or the radio) on it. That sounds low to me though.

    I also don't know how much voltage it will tolerate and if you are willing to let the smoke out of it by guessing wrong. I'll bet low voltage might be bad for it too at its age.

    Of course, you could also just have the radio converted and be done with it. Tayman Electrical stereo solutions for collector cars

    Then a cheap reducer like this will handle the gauges. 12V to DC 6V Waterproof Converter Step Down Volt Module Power Supply 18W US | eBay
     
    • Agree Agree x 1
  5. Mike McGuire

    Mike McGuire Member

    Messages:
    177
    Likes Received:
    33
    Joined:
    Aug 1, 2016
    Location:
    new hampshire

    Happen to have a photo of the generator handy? I'm trying to convert my 55 to 12V and have the 6V version with power steering pump combo. It would be nice to see the physical differences. Thanks,
    Mike
     
  6. paul tracy

    paul tracy New Member

    Messages:
    5
    Likes Received:
    1
    Joined:
    Apr 4, 2021
    Location:
    sun city Arizona
    There is no physical difference. they are Identical

    6415.jpeg
     
  7. paul tracy

    paul tracy New Member

    Messages:
    5
    Likes Received:
    1
    Joined:
    Apr 4, 2021
    Location:
    sun city Arizona
    I bought one of those on ebay. Where do I connect it? can I hook it up in the engine bay? The gauges all seem to jump off one gauge so I dont know where to put it.
     
  8. Mike McGuire

    Mike McGuire Member

    Messages:
    177
    Likes Received:
    33
    Joined:
    Aug 1, 2016
    Location:
    new hampshire
    Thanks! Looks fairly similar.