12V power outlet on 24V M38a1

1952 - 1968, M38A1, M170, questions, discussions, regarding anything related to the M38a1 series.
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Old Marine
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12V power outlet on 24V M38a1

Post by Old Marine » Thu Dec 30, 2021 9:23 am

I have a 1962 M38A1 (24V) and want to install a 12V power (Cigarette lighter) outlet. I have a 24V-12V adapter. I don't want to drill holes. I don't see any outlets from my battery box (apart from main batt power). Is my best bet to splice into 24V ignition somewhere and mount my adapter with double sided tape under the dash? Advice?


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Bill H.
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Re: 12V power outlet on 24V M38a1

Post by Bill H. » Thu Dec 30, 2021 10:25 am

You don't need an adapter. Just run it off one battery and isolated from the rest of the system. I've seen 12 volt power sources mounted clamp style off the lower lip of the dash, no holes needed.

You can feed a back14g wire on the underside of your main cable through the grommet and into the dash. On the underside of the cable it should be pretty well hidden from view.
Bill H.

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BJBoehm
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Re: 12V power outlet on 24V M38a1

Post by BJBoehm » Fri Dec 31, 2021 6:40 am

I wanted to do the same thing on my M422 but also wanted a USB outlet for a phone or whatever. With too much time on my hands I probably over engineered it. First got a combo USB/cigarette outlet from eBay, then a 24V>12 volt buck transformer also from eBay. Then got the overall size and depth that was required to house these and ordered a custom aluminum box that would hold devices comfortably. Then cut the cover to fit the to fit the USB/cigarette outlet. Painted the cover and box USMC green. Routed the 2 conductor 16 gauge jacketed wire through the back of the box and found an unused hole through the firewall and used alligator clips to connect to the battery positive and negative battery posts. Mounted the 4 3/4"X 3"x2 1/4" deep box to the underside of the dash with two sided industrial Velcro. The whole thing can be removed with no damage and wiring is. Tucked out of sight, looks pretty good I think. Bills suggestion would work equally well but again, too much time on my hands. Would post a photo if I. Could figure out how to. If you want I can. Email one to you. Total cost was probably less than $40.


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