- Battery Powered
- A/C Powered
Most smaller machines will use battery power and will be exhausted after roughly two hours of play and then need to be taken and charged overnight. The batteries are sealed, which means they are much more durable, but they cannot be replaced during play. The only way is to recharge them. There is however one kind of battery powered tennis ball machine that can be replaced, which will give you a bit more playing time.
A rechargable cable should be supplied, which you need to plug into your outlet to recharge for the required amount of time. Anything less can result in shorter charged time for your battery.
An A/C powered tennis ball machine can only be used when plugged into a household outlet. These do not run on batteries at all. Many private courts prefer to use these as they can be used without the worry of battery life. Not everyone has this option though.
There are some AC-DC machines out there that use both. They can have batteries and an option to use an outlet.