solar charger effectiveness

Roy, with small solar chargers it gets even worse. There are people here that can explain battery chemistry better than me, but there will be undesirable side-effects if you try charging from 50% to 100% at 13.6V or lower. It's like trying to make a tea with a lukewarm water - you can infuse it all day long and it still won't be any good :)

But when it's already fully charged, this gizmo will keep it from self-discharging.