Solar Ammo Can Disconnect Switch

by admin on July 26, 2018

On the original Solar Ammo Can project, I got a few questions about a battery Disconnect Switch. “Don’t we need one?” Well, the answer is NO, but let’s discuss this deeper.

Many battery chargers can become a slow drain on a battery if they are left permanently connected, but are NOT powered up. That’s not a problem on a device which is regularly charged, but can be an issue on a device put into storage or otherwise not used in a while. In the case of the Solar Ammo Can, even the solar charge controller CAN become a drain on the battery.

So, how do we prevent the charge controller itself from becoming an unnecessary drain on the battery?

The easiest way is simply to unplug the main 12+ positive wire from the battery. I designed the project using Velcro, so that I could easily pull up the faceplate and unplug from the battery.

Alternatively, you could also remove the main automative-style 20A fuse. Either way completely disconnects everything from the battery, and prevents any accidental draining.

But what if you want it to be super-convenient and NOT have to pull up the faceplate?
Originally, I designed my project NOT to have a dedicated disconnect switch, as I liked the way everything laid out, and for me, it wasn’t inconvenient to pull up the faceplate and disconnect the main red wire or pull the fuse. I also liked having the switch on the quad-output turn on and off just those components.

But since people have asked, I’d like to show an alternative way of wiring things up where we repurpose that same switch to act as a main disconnect.

To start with, wire up the project as we’ve already shown in the original step-by-step project video, with the following changes:

  • Run the 12V Battery Terminal to the center terminal (+) of the switch
  • Run the Switched output of the switch to the BATTERY+ terminal of the solar charge controller
  • Run the LOAD+ output of the solar charge controller to the 12V cigarette lighter plug, USB ports, Secondary Voltmeter, and 12+ output banana jacks. (The change is that the +LOAD is NOT going to the switch anymore.)

When using the Solar Ammo Can, make sure to turn the switch to ON. The display on the solar charge controller will come on, as well as the lights on the quad-outputs. Turning the switch off will power down everything INCLUDING the charge controller. This prevents any battery discharge when storing the unit.

As a reminder, make sure to turn the switch ON while trying to CHARGE the Solar Ammo Can, otherwise no amount of sunlight will charge the battery!

If you are interested in purchasing a laser-cut faceplate, they are now available for sale.

I hope you’ve enjoyed this project, and that it helps you learn a little more about batteries, solar, 12V DC, and DIY projects.

If you have any questions or comments, please let us know!

Until next time, stay charged up!
-Ben Nelson

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