Van power to outside of vehicle

[jls]

I'm looking for a (hopefully easy) way to use the coach batteries on my Roadtrek Agile to power a heater at night outside the vehicle when it is all closed up and locked.

There aren't any power outlets that i'm aware of on the exterior and i think power cords are too thick to fit through the moldings around the doors. There is the shore power connector but i think that only goes one direction into the inverter?

Any ideas?

[GeorgeRa]

Are you planning to use electric 120VAC heater? You must have a very large battery bank. Here is an outlet for AC, make sure to use GFCI protected line.

https://www.amazon.com/Weatherproof-...a-817590954176

[Nic7320]

Heat requires a lot of energy, so battery powered heat will be impractical. But if you're outside, you have the advantage of not caring if you create a lot humidity, as it is outside your rig.

This is the ideal place to use a Mister Buddy type portable catalytic heater run off a small propane bottle. We spent a chilly evening huddled around one at a picnic table, and while all the other beachgoers left, we were chatting away and enjoying ourselves.

Now if you're a tent camper, then your idea can work. Install a weatherproof GFCI outlet on the side of the vehicle, and use an electric blanket inside your tent. Heating air takes lots of power, but heating just the area you are sitting or sleeping can be much more efficient. Make sure your inverter has a DC low voltage disconnect and be prepared for the heat to shut off.

[GeorgeRa]

Good point about electric blanket, but 12V one could be a better option if wire gauge <> distance is reasonable.

[Nic7320]

I ran some numbers for common wire sizes from 16 AWG to 6 AWG for a 120 watt load on 12 Volts and 120 Volts. Using !2V is going to require some pretty hefty wire!

I'm going to check the numbers and post them.

[Nic7320]

"The NEC recommends that the maximum combined voltage drop for both the feeder and branch circuit shouldn't exceed 5%, and the maximum on the feeder or branch circuit shouldn't exceed 3%."


So to power a 120 watt load (typical of a 'twin size' electric blanket) a distance of 50 feet away and follow this 3% recommendation, you would need rather large and expensive 4-AWG wire. 6-AWG was very close at 3.2% drop. 8-AWG had a 5% drop, and 10-AWG had almost 8% drop. 12-AWG had about 12% drop, and 14-AWG had a 17.4% voltage drop, and lost almost 18% of the power in the wiring. So using an 85% efficient 120 VAC inverter (or better) can be more efficient than running DC with 14 AWG wire size.

And this is just a single 120 watt load. Plug in another blanket or move further away and again, you need larger wire.

But at 120 VAC using inverter power, the wire is no longer an issue if you're only drawing 120 watts, even with cords as small 16-AWG. And that's why we use higher voltages for appliances in our homes.

The spreadsheet was done in OpenOffice and available if anyone needs it.

It's unlikely RVs follow this 3% guidance on DC circuits. Does anyone know how RVIA deals with DC circuits?

And this is not exactly a "rule" as much as it is a recommendation.

"Contrary to common belief, the NEC generally doesn't require you to size conductors to accommodate voltage drop. It merely suggests in the Fine Print Notes to 210.19(A), 215.2(A)(4), 230.31(C), and 310.15(A)(1) that you adjust for voltage drop when sizing conductors. It's important for you to remember that Fine Print Notes are recommendations, not requirements [90.5(C)]"

(quoted source: https://www.ecmweb.com/national-elec...ur-system-down )

[hbn7hj]

I use two 120 volt mattress pad heaters on battery through an inverter. Works very well. I wouldn’t even think of using 12 volts going any distance. You could install a 120 volt RV exterior outlet with cover. Many RVs have them.

https://www.etrailer.com/RV-Power-In.../37247505.html

Mattress pad is Electrowarmth.

[hbn7hj]

Forgot to tell you the refrigerator is usually plugged into a dual outlet and it is usually accessible from the outside. You would need to tie an inverter to your AC system through another transfer switch. Problem solved.

[Nic7320]

Originally Posted by hbn7hj

You could install a 120 volt RV exterior outlet with cover. Many RVs have them.

It should be on a GFCI protected outlet, since exterior environments are often wet. The covered outlet you posted won't fit over a GFCI, but it can still work if it's connected to a GFCI device somewhere inside the RV.

I just checked mine. It has a GFCI sticker, so it's sharing the bathroom GFCI outlet.

[David Pouliot]

Why not run a propane heater.

Originally Posted by jls

I'm looking for a (hopefully easy) way to use the coach batteries on my Roadtrek Agile to power a heater at night outside the vehicle when it is all closed up and locked.

There aren't any power outlets that i'm aware of on the exterior and i think power cords are too thick to fit through the moldings around the doors. There is the shore power connector but i think that only goes one direction into the inverter?

Any ideas?

[Jon in AZ]

What are you trying to heat, presumably when the van is parked and unoccupied?