Our DIY 120v system starts with a 30amp twist receptacle with a 15amp plug on the end.

This required us to drill a hole in the camper wall. We didn't hit the frame this time, but we did hit some wires just under the aluminum outer sheet. We think these go to the red light in the upper left corner of the camper back wall.  It was pretty easy to splice them back together so no major problem, but just beware that there are some wires in this area.  You can drill tiny pilot holes from the inside to find the frame, but that doesn't help find the wires!

We used a 10 gage 3-conductor cable to go from the 30amp receptacle to the circuit breaker panel. It is about 6 feet long.  We don't have any huge amp draws and probably rarely get above 7 to 10 amps total so this seems just fine.

When we expanded the drivers side bench in our FWC Hawk shell to make a more comfortable seat and room for a water tank, the 5-inch wide compartment holding  the factory 12v gear was  expanded to 10 inches and this made room for the 120v equipment.  It was a little bit of a tight fit, but it works.  Across the top of the expanded electrical compartment is a conduit for the fresh water inlet, to make absolutely sure no water gets into the electrical space.

This 120volt, 30 amp breaker box from Paneltronics had 3 circuits--just enough for the Iota Battery Charger, the 2-way refrigerator (12v and 120 v), and a pair of outlets.  The Outlets switch had to be trimmed down to fit under the grey conduit but we rarely use it.  Tight fit!

The Iota DLS-30 battery charger is the same charger that FWC was putting into their built out campers in 2019 when we did our build, so we used it.  The little green box with the green light is the IQ AGM controller that controls the bulk, absorption, floating and equalization stages to assure optimum battery life.  The bulk charge stage applies a 14.7v, followed by 14.2v in the absorption stage and within about 6 hours the voltage drops to 13.6v to maintain the fully charged battery.  This protocol rapidly brings the battery to full charge but avoids overcharging at the higher voltages. About once a week, an equalization stage cycles through all the stages to minimize sulfation that may occur during long term storage.  

The Iota charger generates some heat and has a fan that runs as needed. The fan should have about 4 inches of unobstructed space around it.  We had a very tight fit and  could only allow about 3 inches, but it seems to work fine.

Important note:  The DLS-30 installation guidelines should be carefully reviewed and followed, including not installing it in a  zero clearance compartment, wire gauge recommendations and requirements for a Type III circuit breaker to be installed within 18 inches of the battery.

IOTA DLS charger installation guidelines should be carefully followed, including the following:

Recreational vehicle applications require a type III circuit breaker be installed within 18" of the battery, connecting the battery positive to the line side of the breaker, and the IOTA unit to the load side.  

The circuit breaker we used is shown to the left.

The schematic really helped to understand how to wire up the panel, but the two electricians in the family were a big help too.  

Wiring for the panel box seemed like a rat's nest, but eventually it all fit in the box and worked fine the first time.

Two air vents on the side and an opening under edge of the seat provide ventilation.  On a hot day when we are bulk or absorption charging, I prop the lid (seat) up even wider just to make sure as the charge shuts itself off at around 105F.

Here is the video from our Sagebrushers YouTube Channel