As you probably already know there are dozens of types of batteries on the market at the moment, each with different specifications and purposes. Therefore you can imagine that there are also several types of battery chargers and if you don't know anything about them, read the following lines because we are going to have a look over these types.
The most common type you will encounter is a simple battery charger that does nothing more than supply a constant voltage or current to the battery. With no protections and no way of controlling them, this type definitely isn't the most recommended one, but it sure is the least expensive.
If you want to take things a bit further you can go for a timer based battery charger that stops after a certain period. Unfortunately you have to match your batteries to that period if you want to obtain the best results and not overcharge them or have them partially charged.
The type of battery charger you will want to spend your money on is an intelligent charger that has the capability of charging your batteries up to 80 percent in about an hour and then charge them slowly until they are full. Indeed, this type is the most expensive one, but of you care about your batteries, it is the obvious choice because it protects them, insuring a longer life period so that they will never let you down when you need them the most.