The process of restoring or reconditioning batteries that you considered to be dead is something anyone can do at home. Once you learn how to do it, you realize how simple the processes are. There are a couple ways to do this and it depends on the type of battery you are working on. About 95% of the rechargeable batteries can be restored.
Since not every battery can be restored, a simple test will tell you if it worth trying. The tools or instruments needed are not expensive and should be found locally if you want to purchase them, some people have made their own. Considering the expense of replacing some types of batteries, reconditioning them is cheap.
Batteries used for automotive and marine use are used around the world, and the cost in some countries can be prohibitive if they need to be replaced. Having a way to restore or recondition their batteries would be a savings and would even be a great business opportunity. You could be a source for people to bring their battery to and you could charge them a fee to recondition their battery.
Those that have solar power systems in their homes and need batteries to store the power could benefit from restoring batteries. You can find batteries from golf carts and other sources that use rechargeable batteries for free or very cheap and put them to work for you after reconditioning them. Being the battery is an expensive part of solar power system this would save some money.