Shore Power suggestions, DIY. Multi-circuit 120v 20-30 amps.

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Cypress302

Junior Member
Joined
Jan 3, 2026
Posts
1
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Location
Laurel Delaware
Ram Year
2012
Engine
5.7
I have a 2012 Cab and Chassis (5.7L) with a early 2000's 9' utility body. The time is near to upgrade the toolbox, and I'd like to make my own Shore power setup for the following applications:

- Block heater on a programable thermostat/timer (suggestions encouraged). Perhaps Shore Power > Timer > Thermostat > Block Heater.
- 1.5 amp battery sustainer (existing)
- 15 amp circuit for battery chargers
- 750watt or similar heater mat to keep tool batteries warm (also thermostat controlled).
- Existing setup (no supplemental heat) is in a lunchmate cooler. I'd seek a rectangular cooler and likely stack the matt, a scrap of aluminum plate, and then pile the batteries in.
- Heater for adhesives, perhaps combine the battery and caulk/adhesives insulated cabinet; ie, take a portion of a toolbox and line it with rigid rockwool.

As for the assembly, I'm thinking two 15 amp circuits fed off a 30 amp, auto ejecting shore power plug, or two 15 amp circuits with a selector (heaters and sustainer on one, 15 amp outlets on the other) which has one 15 amp auto ejector so that I have I have a wider range of locations to use the shore power from. I figure someone in here has done upfitting work and might have some suggestions as I reckon UL equipment for homes (what I'm familiar with) isn't the best option for automotive use. I'm familiar with 12v circuits and supply from personal fishing boats, and I have limited experience with power on commercial fishing boats (I crewed the boats, but never had to maintenance the AC electrical systems).

This is probably more thought experiment than practical right now, because I reckon this setup could easily hit $1,500 and if I had that laying around, I'm probably going to blow that fishing instead, but it's something I've always thought about to keep batteries and adhesives warm.

Thanks for ya'lls input.
 
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