Turn a Solar Charge Controller Into Wall Powered 12v Battery Charger

Introduction: Turn a Solar Charge Controller Into Wall Powered 12v Battery Charger

About: Check out ThriftStore Hacker on YouTube! Where junk makes neat stuff! Follow me on Twitter @ThriftStoreHack https://twitter.com/ThriftstoreHack

This Instructable started to solve a problem i had. I needed to charge a 9 amp hour SLA battery but i only had a standard car battery charger. The car battery charger was way too high of amperage to properly charge my SLA battery.

I started to dig around in my parts boxes to see if there was something i could piece together to make a low amperage battery charger.

Check out my other videos and subscribe to my channel

ThriftStore Hacker on YouTube

Teacher Notes

Teachers! Did you use this instructable in your classroom?
Add a Teacher Note to share how you incorporated it into your lesson.

Step 1: Charge Controller and Wall Wart for Power.

Digging through my extra parts i found a 3 amp solar charge controller.

3 Amp 36 Watt @ 12v maximum input.

Has overcharge protection. This feature allows the controller to shut off the power going to the battery when it hits a specific voltage. This controller cuts off at 14.4 volts which is the maximum charging voltage for the SLA battery.

The undercharge protection feature is not really needed if you plan to use it as a battery charger. This allows you to draw up to 3 amps of power from the controller (the Load port on the controller). If you discharge the battery to a specific level (this controller 11.1v) the controller shuts the power off to that port.

I will use a 14.4 volt 1 amp (14 watt) wall wart power supply for power. The wall wart is low enough amperage that it will not fry the controller or hurt the battery.

Step 2: Connecting Battery and Power

The controller has 6 ports for wires. 2 wires for solar panel input, 2 for the battery, and 2 for devices.

The battery is connected to the controller and a small light is installed into the devices port. The wall wart power supply is connected to the Solar panel port on the controller.

The wall wart is providing voltage to the solar panel port just as a solar panel would. When the battery gets to maximum charge the controller will stop charging it.

Step 3: Ideas and Future Use

Since this charged my SLA battery quick and safely on wall power i want to make a dual charging rig.

Putting a power plug on my 15 watt solar panel that matches the plug on the wall wart will allow my charger to run on wall power where available and on solar power while out in the field just by switching the source at the power input socket.

In an extreme emergency it would also work on a much larger car battery. If i am camping and the headlights get left on in the car running down the battery. I could hook this setup up to the battery with a solar panel and possibly get enough charge in a day to start the car.

Please vote for me and subscribe to my channel to see all kinds of other hacks on YouTube :)

Thriftstore Hacker on YouTube

Sensors Contest 2016

Participated in the
Sensors Contest 2016

Be the First to Share


    • Backyard Contest

      Backyard Contest
    • Silly Hats Speed Challenge

      Silly Hats Speed Challenge
    • Finish It Already Speed Challenge

      Finish It Already Speed Challenge

    3 Discussions


    2 years ago

    Have you left this setup plugged in for months at a time? I want to enable it with a Solar Deep cycle battery, but it is much bigger, 120 amp hour.... i wonder if that changes the requirements for the adapter.

    ThriftStore Hacker
    ThriftStore Hacker

    Reply 3 years ago

    I have used this rig many many times with the solar panel and the wall wart. It has no problems with heating up or drawing more than rated current. I think if the charge controller may be in play here. Some kind of circuit protection.
    If you get to the bottom of this please post back here and let me know.