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12 volt conversion question about head light relay
  • ivanz62
    Posts: 172Expert Adviser
    I want to use a Hudson Autolite headlight relay from 40-41 Hudson because it looks correct. Can anyone suggest how much resistance should be added to the power to the relay coil to drop the voltage to avoid trouble. Or perhaps someone's experience is that the relay will hold up to 12 volts? Any experience out there?
    Thanks,
    Ivan
  • Ken U-Tx
    Posts: 1,165Platinum Member
    Hi Ivan, maybe you can put a couple of modern 12 v Bosch solid state headlight relays inside the old Autolite headlight relay, under the metal cover, where no one would notice?
  • Ken U-Tx
    Posts: 1,165Platinum Member
    One for high beam and other for lowbeam.....
  • bob wardbob ward
    Posts: 533Platinum Member
    You can buy an all in one high/low beam relay, not sure about a solid state version though. Hide the relay near the headlights.
  • Tallent RTallent R
    Posts: 1,602Platinum Member
    The above suggestion of 12volt relay inside the old cover is good option .Also you can find dropping ressistors on Ebay in all amperage capacities for anything from running dash guages up to running wipers or blower motors
    Roger
    Retired Tech.
  • Park_WPark_W
    Posts: 2,055Platinum Member
    Ivan, use an ohm meter to measure the resistance of the relay coil. That's the resistance you need to insert to run it on 12v. The resistor should have a wattage rating of 36/R, where R is the measured resistance of the relay coil. You can probably break into the relay coil circuit and fit the needed resistor inside the relay cover.
  • ivanz62
    Posts: 172Expert Adviser
    Gentlemen: Thanks for all your comments. I am confident the dimmer switch can handle the higher amperage of modern lights and just want to protect the light switch so one relay should do. And Park's suggestion of modifying the coil inside the Autolite unit has great simplicity to recommend it! Ivan
  • MikeWAMikeWA
    Posts: 1,435Platinum Member
    Here's a nice piece on putting a modern relay inside the old case- its for an OD relay for a Studebaker, but the same principles. Looks like a fun project.

    stude.com/FAQ/Questions/OdRelay/Default.htm
  • barrysweet52barrysweet52
    Posts: 276Gold Member
    Interesting Stude article, well written, good photos, couldn't see terminal B, but well done and thanks. Barry
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