Batteries slowly deteriorate from internal corrosion, active materials getting used up, And from Sulphation, electrolyte loss and other things. No matter how well you look after them

When is the correct time to replace your powerchairs battery?

When YOU notice they no longer support your daily usage pattern.

Almost all quality mobility batteries have the same "lifespan" and number of cycles if used in the same way. Although with batteries you do tend to get what you pay for.

Cheap batteries are usually pretty crap! By quality I mean MK, Odyssey, Optima, Sonnenschein, and one or two other true deep cycle batteries. All the rest are a waste of your money unless you barely use your powerchair or scooter.

The reason some people get 6 or 7 years from a set of batteries and others (myself included) replace them yearly is because of the usage patterns.

Because I really do work my batteries hard and deplete them deeply every day I both wear them out faster, and also NOTICE that the range has decreased, even when the battery has only really lost a little range. Most people don't go far enough to notice.

The batteries I throw away, would probably be "good" for another five years if I gave them to someone that never really goes very far. Because they would never get to the point where I found them lacking since they do not travel far enough. This is the main reason some batteries seem to last for huge lengths of time.