DIY Camper Battery Box

Spent the last few weeks of my maker time making a battery box with and for my son’s camper.
It was a painstaking project but also a lot of fun. I was new to making high current batteries and solar connections.

We used a trailer box from HF and modified it to hold 2x batteries and some “stuff”.
The project included fabricating and installing; a battery mount, USB & 12v outlets, fuse panel(s) solar charging connections, charging/capacity meter, key lock, light with the lid switch, and main battery switch.
It was made water-resistant through the use of plastic, silicone, and stainless materials. All connections were crimped and soldered. Most of the parts were bought on amazon and I was pleased with the quality.

The control panel is 1/4" acrylic, painted black on the backside so the front side is durable.

One challenge was the key lock. We could not use the one that was on the front verticle surface because the propane tank was in the way. Therefore we mounted another on the top surface. But how to keep water from seeping into the keyway of the upward-facing lock?

:bulb: :bulb: We made a mold from a medicine bottle and cast a cover with the silicon/corn starch method. After filling the mold the actual lock is pushed into the silicone. After drying the lock is pulled out. The finished cover fits over the lock with a slot cut into the top for the key to enter. Not waterproof but certainly water-resistant. I plan to re-make a black one! The green just violates the theme!


Having been involved with an offroad racing group for a few years, if you soldered any of those wire lugs it will help to put cable hold-downs to keep the wires from moving at the soldered ends.

That box fits quite nicely in that spot and love all the outlets. I might get one for my toyhauler for supplies, not for batteries. I went LiFePo4 for the toyhauler and LiON for our NEV. I was soooo done with Pb acid batteries corrosion, maintenance and need to be always fully charged.


You may be better off using crimp lugs.

A soldered connection makes a ‘hard’ transition between the soldered part and the free part. This becomes a fulcrum for bending and produces huge strain fo small movements. The wires will fatigue break at the transition.

What you want is a strain relief over the crimp. I use either heat shrink tube or hot melt glue. This forms a strain reliever and your wires will last longer.

Also use multi stranded wire wherever you have movement or vibration.

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You may well be right!

I think it’s a trade-off between corrosion at a crimp causing a voltage drop vs work-hardening at a solder joint causing a mechanical failure.

I have never had a solder joint fail but have experienced many high resistance crimps. I feel that it is difficult to get a good gas-tight joint with a crimper.

In addition, I did not have the budget for the right crimp tool and I do not believe that the hammer-anvil approach creates a good crimp.

The wires I replaced were crimped and demonstrated a lot of corrosion.

Since the box and the new hold downs now isolate the batteries from most of the vibration I decided to go with solder and heat shrink.

All the new wire is stranded copper.


BTW I hated the green key cover so I finally got one that was black.

Most additives I had around the shop changed the chemistry of the silicon and it either did not dry or turned out crumbly.

I ended up using black “milk paint”.
Just a pinch of it added to the cornstarch/silicone mix did the trick.


My security camera 12v DC power wires corroded 500mm back from the ends over 10 to 15 years.

The highèr quality cameras also accept AC supply. Guess that tells us something.

I was very surprised to see this, and there was little difference between the crimped and soldered leads. Ii think it was the positive that had the most corrosion at the camera end. The supply ends are all fine.

I think that DC is the main culprit and remember my dad (an old time Elec eng) mentioning that corroosion was one of the reasons to distribute AC rather than DC. My dad worked for the phone company in the 1930s and would have experience of corrosion from DC on rural lines.

Probably something we just have to live with.