DIY Waterproof Battery Box for RC Car – 6‑Step Build

Tired of your RC car dying the moment a splash hits the battery? In this guide you’ll learn exactly how to build a waterproof battery box for RC car that keeps moisture out, stays under $20, and fits in minutes. Follow the step‑by‑step process below, download the free 3‑D‑print files, and race rain or shine with confidence.

Why a Waterproof Battery Box Is a Must

A single puddle can short‑circuit a cheap plastic case, killing the battery and your race. Protect RC car battery from water damage by sealing it the same way a waterproof phone case does. The right enclosure gives you the peace of mind to push the limits on any wet track.

Parts List (Under $20)

3‑D‑printed shell – designed for a 2S LiPo, free STL on my blog
EPDM rubber gasket strip (1/8" wide) – $5
Silicone O‑ring for the lid – $2
Two 1/4‑inch waterproof cable glands – $4
Marine‑grade silicone sealant – $3
M3 screws and nuts – $2

Total cost: ≈ $18. All items are easy to find at a local hardware store.

Step‑by‑Step Build Guide

1. Print the Shell

Use PLA with 20 % infill. Print both the body and lid in the same orientation to keep layer lines aligned. The STL includes a raised lip where the gasket will sit.

2. Install the Gasket

Cut the EPDM strip to match the lip’s perimeter and press it firmly into the groove. EPDM stays flexible even when the box warms up, creating the first line of defense.

3. Add Waterproof Cable Glands

Mark where the power leads exit, drill 1/4‑inch holes, and screw the glands in place. Slip the wires through, tighten the nuts, and you now have a watertight passage for your connectors.

4. Seal the Lid

Apply a thin bead of marine silicone to the inner edge of the lid, then place the silicone O‑ring on the outer edge of the shell. Snap the lid on; the O‑ring and silicone form a double barrier against moisture. Let the silicone cure for a few hours.

5. Fasten the Enclosure

Secure the lid with four evenly spaced M3 screws. Tighten just enough to compress the gasket without cracking the plastic. This keeps the box light and sturdy.

6. Test for Leaks

Submerge the sealed box in a bucket of water for one minute. No water should enter. Follow with a gentle pressure test using a rubber mallet. Re‑install the battery, connect the wires, and take a short test run—everything stays dry and powered.

Final Tips & Maintenance

Run a quick dunk or spray test before every race to catch any missed spots.
If you need a larger capacity, simply scale the STL in your slicer and adjust the gasket length accordingly.
Store the enclosure in a dry place when not in use to prolong the silicone seal’s life.

With this DIY waterproof battery enclosure for R/C car, you’ll never worry about puddles stealing your podium finish again. Download the files, print, assemble, and hit the track—rain or shine.