The AA Car Battery Solar Charger is a perfectly good solar panel for ensuring that your car battery does not run down if the vehicle is not used often enough. Its one weakness, however, is the cable coming out of the solar panel, which is prone to breaking, in part because the gauge of the internal copper wire is so thin. Worse still, it is all too easy for a wire break to go unnoticed, since the cable's insulation can remain intact, and the blue flashing LED on the solar panel will continue to flash irrespective of whether the car battery is being charged or not. Consequently, if a wire break does occur inside the cable, there is a good chance you will be unaware of the problem and one day when you try to start your car - it won't! I encountered this very problem...and this is how I fixed it.