Question...is it safe to use one of these while sitting on the lake to keep battery charged..with running the stereo for a awhile im always worried about the batteries dieing.
It is safe as long as the panel has a good voltage regulator module. Solar panels themselves can put out anywhere from 2 volts to 20 volts depending on how much sun they get, a VRM makes it a nice clean 13 or 14 that is safe for the electronics