Not all battery types can be fixed, below are some of the types that can sometimes be fixed.
- Lead-accid: Flooded & Absorbent Glass Mat (AGM)
- Lithium Ion: Li-On, sort of it's complicated
Lead-acid batteries are the kind typically found in cars, trucks, RVs and more.
They're common and stable with a long history of improvements.
They are more affordable than Li-On batteries but they are not as long lasting or energy dense.
They are, however, easier to maintain and fix if needed.
Li-On batteries are newwer technology and are appearing in more and more places includeing automobiles and RV's.
They are less common and less stable with known possiblity of fire and explosion if they are not kept in a secure way.
They cost more but they are also more durable and last much longer than lead-acid batteries when they are properly maintaned.
They don't require as much "maintenance" as lead-acid batteries in that they are sealed and do not require adding fluid or anything to them.
They require a proper charge voltage and storage location and with those two things will last you years and hundreds if not thousands of charges.