Solar Update-Part 1


Thunderbolt Charge Controller

In a post a few weeks ago called Faulted I wrote about us struggling with our solar array.  We couldn’t get our batteries to hold a decent enough charge to run the system.  I attributed the issue to cloudy/hazy days.  I now believe that may have been a small part of the problem.  The larger issue turned out to be in the connection between the batteries and the charge controller and the charge controller itself.

Remember that the charge controller’s job is to maintain battery life by keeping the batteries in that sweet spot between 11.7-14.5 volts.  Doing some checking around the Internet I found an article on by Practical Technology about our brand of charge controller.  Read it here.

If we applied what the article said to our system-our contoller was allowing the batteries to discharge at night.  This made sense.  During the day with the sun shining, voltage was flowing from the panels to the batteries (correct). At night once the flow from the panels stopped the batteries were sending charge back to the panels.(Incorrect!) The controller was not doing its full job.

According to the Instructables article adding a diode to the system would stop that problem.  A diode in simple terms is a one way valve for electricity.  It only allows electricity to flow a certain direction.  This addition to the system should stop the problem of nightly discharge. 

Charge Controller with Diode courtesy of

Last weekend we set out to find a diode.  We checked Walmart, Harbor Freight, Battery Joes & Radio Shack.

No dice. Very frustrating. This issue had been going on long enough! 

Our original solar array was great and worked like a charm.  At some point we had gotten fouled. Our troubleshooting processes had not provided a solution and we were still in the dark-pardon the bad pun.

There was one thing left to do. It was time to disassemble the system and start over-taking it back to zero-with a different charge controller, new wires, different lights, and charged batteries.  

That’s just what we did.  I’ll post the products, process, hidden mistakes and outcomes next time in Solar Update Part 2.  See you then!


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