Light weight batteries?

^^Juz' sayin^^ but terminal voltage means little so far as LI batteries. We fought this when I worked at the wheel chair joint. An automated system such as any electronics/ cameras/ etc, or wheelchairs generally the battery condition indicators are questionable. All LI batteries at least the high power ones, have a rather substantial "battery management" package that is also subject to problems

All LI based batteries should be charged on specialized chargers