12v Mods &

Amp Load by Device

We made only three minor modifications to the 12 volt system in our 2019 Hawk Shell. They include a battery monitor, extra USB ports and 12v sockets in the front of the camper. A 12v socket was needed for our 2-way refrigerator. We describe these minor additions here, along with measurements we made of all the 12v loads in the camper. This data can support an amp-hour budget and that can help you better understand your battery and solar panel needs.

Before the Mods, let's look at the 12 fuses/wires in the Hawk Shell as we received it in 2019.

12v Fuse block as received

There was one open fuse slot when we got the camper from the factory, the upper left slot with the green wire. The system ground or negative is the white wire at the bottom by the yellow tag.

12v Wire/Fuse list as received

The green wire was for the Exterior rear flood light option which we did not choose. So, we just unplugged the green wire and used the slot for a circuit to power the USB ports and 12v socket in the front of the camper.

Now let's look at the fuse block and new schematic with the added circuit.

Fuse Block with new circuit.

Now the upper left fuse slot is has a 15 amp fuse and a new wire (it is red with black tape, not fully visible). The wires for the new circuit can be seen at the top, on their way to the front of the camper.

Revised fuse block/wiring schematic.

I re-did the fuse box schematic and pasted it to the inside cabinet door to make sure there is no confusion about the circuits, wire colors and proper fuses. Only the upper left box changed.

Here are the three minor modifications we made to our 12v system

(not including solar which we'll cover soon!)

12v: Battery Monitor

The most important thing you can add to your Four Wheel Camper shell, if they do not yet come standard, is a device to monitor your battery voltage and current, or amps. There are a number of great battery monitors, but our philosophy is don't buy more than you really need. This is a very inexpensive meter that has worked for us for over 3 years. A deep cycle RV type battery such as the 79AH AGM battery that we got standard in our shell has a useable range of about 12.25 v to 12.75v for a total range of about 0.5v. If your battery goes below about 12.25v its life can be shortened. So, you can't properly manage your battery for a reasonable lifetime without some kind of voltage indicator. I think FWC may provide one in shells by now. If not, get one!

Here is a link for this one: https://amzn.to/3vdsMCJ

As an Amazon Associate I earn from qualifying purchases when you purchase from my links. It is a small percentage and does not affect the cost to you.

USB ports in front of camper

We were running wires to the front of the camper for the refrigerator already, so we decided to add a dual USB plug so that we could charge a device on the table or above, on the bed. These are also inexpensive and now they come with on/off switches and even voltage displays so you can be more alert to your battery state of charge.

Here is a link for the dual USB port we got, updated with a switch: https://amzn.to/3aZ2KMz

As an Amazon Associate I earn from qualifying purchases when you purchase from my links. It is a small percentage and does not affect the cost to you.

12v "Cigarette Style" Sockets

Our 2-way refrigerator is in the front passenger side corner, so we needed a 120v and 12v plugs in that area. The top strip shown here is 120v, but the bottom two sockets are 12v. They are mounted in a small plastic junction box which fits nicely in the narrow compartment right under the refrigerator. See the "120v Mods" page for info on the 120v receptacle.

Here is a link to the 12v sockets: https://amzn.to/3zq13RR

Here is a link to the white junction box we used: https://amzn.to/3ztoVnx

As an Amazon Associate I earn from qualifying purchases when you purchase from my links. It is a small percentage and does not affect the cost to you.

Amp Measurements for 12v devices in our Hawk Shell.

Do you need a bigger battery? A solar panel? We used our volt/ammeter shown above to measure the amps pulled by each device in our camper. Note, the furnace and the refrigerator cycle on and off so their average amp draw on the battery is actually much less. For example, the fridge cycles on ~ 20% of the time so its average draw is only 0.63 amps (3.15 amps x 0.2=0.63 amps). However, it runs 24/7 so it uses around 15 amp-hours each day (0.63 amps x 24 hrs). We will put these measurements into an amp-hour budget in the Data page (coming soon!), because we can learn a lot about our usage and charging needs by going through that process .

12v mods video

The video covers our 12v mods and shows how the wires for the new circuit were routed to the front passenger side area. It also shows us making the amp measurements shown above.

In the next installment, we will look at a "Battery 101" or basic battery management info that this newbie learned AFTER getting our first camper. We will also look at our amp-hour budget to see what it can tell us about the battery and solar capacity we need. Both of these topics will be in the next, very nerdy YouTube video, and are also covered in the data section of this site under Battery Stuff.

Inexpensive volt/ammeter battery monitor: https://amzn.to/3vdsMCJ

Plastic Junction Box: https://amzn.to/3ztoVnx

12v cigarette lighter socket: https://amzn.to/3zq13RR

Dual USB Port: https://amzn.to/3aZ2KMz

Dual USB w/voltage display: https://amzn.to/3BbdFNW

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