Review on SUNAPEX 5W 12V Portable Solar Battery Charger: Effortless Charging & Maintenance For Your Vehicle by Roberta Berg

As the built-in charge controller comes with indicator lights, if find the LED on the 12 volt plug to be redundant and an energy drain. The unit comes with a blocking diode, which is good, but the plug LED is not blocked and uses juice 24/7 making a net daily charge very slow. I took the plug apart and cut out the LED. That way I can leave the charger plugged in continuously with little overnight loss. A magnetic strip would be nice to help anchor it to the vehicle. Seems well built and bullet proof. Slow to charge, discharged batteries, I don't there will be any problem in overcharging them.Revised: On further research it appears having the SAE plug reversed is often used, to the extent that SAE polarity reversal adapters are commonly available.I just figured out that the panel and the supplied accessories are wire backwards to SAE normal. This means for example, that when you attach the battery clips to your car battery, you risk having the exposed SAE pin, now positive, to ground out on any part of the car. This will cause sparks and possible burns and even explosion due to battery hydrogen. Plus the accessories won't work, possibly dangerously, with other SAE products like battery chargers.