Adafruit Waterproof 3xAA Battery Holder with On/Off Switch
Keep your power source safe and toasty in these waterproof 3xAA battery holders. They're just like classic switched battery holders, but designed for survival! The case has a rubber gasket around the edge of the case (its black and hard to see in the photos but it is there) and attaches together with 4 machine screws. What we like about this design is that the hexnuts are captive in one side and you can assemble/disassemble as many times as you need. There's a potted power switch and a rubber-boot on-off switch (press to turn on/off). Use with any alkaline or rechargeable batteries for about 4.5V output.
Would work great with our waterproof DC power plugs (just use heatshrink to waterproof the solder connections)
The power cable wires are not polarity marked, use any multimeter to verify the polarity during use.
We also have a 2xAA version when you need a smaller & lighter box