Yes, but it can be any battery with mediocre ampere hour capacity. A small lawn tractor battery would provide enough power to entertain a midsize crowd for several hours. Keep in mind that a lot of those battery powered amps only have sufficient battery capacity for an hour at best, and at very, very low wattage. Many operate on AA or D cell batteries, thus producing less than 5-watts of power for an hour before heading downhill.

One of the things on the spec sheets of most of those amps that is left out is the power consumption in amperes. Sometimes, I manage to find it buried in the repair manuals, only to discover that an amp that is rated at 30 amps is only producing 30 amps of peak power. One that I looked at only produced .4 amps of actual power when you did the math using OHM's Law. And, from my experience trying it out in the local music store, it was totally unsuitable for use with an arranger keyboard.

Hope this helps,

Gary