Bests & Worsts Reviews from Amazon

I was a bit skeptical of these after reading so other reviews, so I did a bit of testing. Hopefully my results will be helpful. My situation is that I am retired, have 2 vehicles and don't have a need to drive much. But it seemed like every time the weather turned bad, the 4WDs battery was dead, and every time it turned nice the rag-top was dead. Not only a pain to drag out a charger, but it's really bad for batteries to sit there dead. So I decided to get one of these and, if it worked out well, get a second so I didn't have to swap it between cars. After a couple months use and a bit of testing, here's what I can tell you: 1) Don't expect this to charge a dead battery. Not designed to, and won't. What it will do is offset the natural loss in the battery and the minimal drain that the vehicle may have when off due to such things as the computer, security system, etc. There is an isolation diode contained within the solar panel to prevent back-feed drain regardless of whether the lighter or clip-on cable is used. 2) The Red LED on the lighter plug is your friend, if you know how to use it. a) Connect lighter plug to solar panel, but do not plug into lighter socket. Aim panel towards sun and observe that LED lights, then aim away from sun and it goes out. This proves that the panel is generating electricity. b) Disconnect lighter plug from solar panel and plug into lighter socket, with ignition off. Verify that LED lights. This proves that socket is live with key off. c) Connect lighter cord to panel, and install panel either on the dash, windshield or (my preference) on the passenger's visor which can be rotated to catch the best sun based on how you park. Protect the panel from the elements; this is not an outdoor panel. 3) Do NOT disconnect when driving, just rotate so it does not impede your visibility. The isolation diode will protect the panel and vehicle from each other regardless of whether the car is running or not. Frequently plugging and unplugging the lighter socket increases the chances of a bad connection inside the socket. If you must disconnect, do so at the panel end instead, and make sure the LED is on before reconnecting. If it ever seems as though it has failed, repeat the tests in step 2 above. If you do the above, I think you'll find this does what you need it to, and does it well. Hopefully this fills in the gaps in the manual, as well.