Lee Hart's Battery Care Basics
Let's anthromorphize a bit, and think of lead batteries as living creatures. A little detective work to fix the problems, and then some tender loving care, will go a long way toward getting the longest life possible for your EV's batteries.

The usual reason you see used EV ads that say "needs batteries" is that the previous owner treated the batteries cruelly or carelessly. Whether by ignorance or laziness, he or she violated some or all of the above guidelines. But unlike your dog or your horse or your brother, batteries are easily replaceable. "Needs batteries" usually means you can get the EV cheaply.