I bought this along with a 25w panel to keep my RV batteries charged. On Sunday I placed the solar panel in the sun and left it out until Monday morning when I heard the carbon detector beep indicating low voltage. Instead of charging the batteries, the controller somehow created a drain and pulled the batteries down to 3 volts. The yellow charge light was still on and I couldn't get any measurable voltage through the controller, even though the solar panel was putting out a constant 13 volts. I only gave two stars because it was easy to install and the price was good.
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