If you only do occasional homeowner or hobby work, you can do well with a single battery charger and two batteries, one to run and one to charge. When you purchase power tools, make sure to buy them all from the same manufacturer line so you can use one charger system for every tool that you own. Some heavy-duty battery chargers can charge batteries of multiple voltage types, which lets you get regular tools for your easy jobs and professional-level tools for your more involved projects.
If you want top-of-the-line performance, select a lithium-ion battery charger system. Lithium-ion batteries run for longer periods of time, have overall longer working life and don't develop memories like the older Ni-Cad or Ni-Mh models. If you run a construction or remodel operation with multiple workers, get a professional charger than can power several batteries at once so each worker can swap out as they need.
For convenience, you can purchase an automotive battery charger. They plug into your cigarette lighter and charge your batteries as you drive or just run the engine. They save you time if you have to head to a jobsite and your battery is already dead. These chargers can also be lifesavers, since they power batteries during blackout or other emergency conditions. Many of these vehicle models plug into some generators so you can keep your tools running at sites without electrical power.
Battery chargers let you take your tools to otherwise inaccessible places to complete virtually any job. They are eco-friendly and prevent the waste of disposable batteries. Check which tools you plan to buy, and grab the battery charger and matching batteries to run them.