See lots of dead batteries (car and marine/deep-cycle/lawn) at local trash transfer station today, I am wondering: Can I recycle dead 'deep-cycle' battery back to full charge via small solar panel (5w) as trickle charging? If I bring my multimeter to check out each dead battery, what is the voltage that acceptable for re-charging? less than 10.5 or ? Just thought to save some $$$... Thanks!