Hey guys

I've been doing some busking with my 3 piece band guitar, vocals, cello, cajon) using a battery powered amp (Korg MMA130), and it's not putting out enough sound.

I saw another busking band that had a huge sound, that was running off a battery and inverter, so that seems like the way to go. So I started reading up, and it looks like deep cycle battery + inverter is the solution.

But I can't seem to figure out what size battery I'll need. The inverter calculation seems more straightforward. Can anyone help me out?

We want to power the following equipment:

Korg MMA130 - 25W consumption
Marshall 15dfx amp - 15W
Boss RC300 - 320ma/DC 9v

and about 3 small pedals, and a small phantom power box.

Any advice on what size battery will do for a 3 hour busking session?

Just get the one with the most amp hours that you can find. That's the one that will last the longest. Should be about $150. More expensive if you get a dry cell Optima Battery, probably closer to $225. The advantage of the Optima dry cell is that it won't leak battery acid all over everything if it tips over, and it will tip over. The downfall of the Optima is that it has less amp hours and will die quicker but should still be around 75 usable amp hours or so.

If you don't get the Optima get a plastic battery carry case.

You will also need a deep cycle battery charger.

I would go with a little bigger power inverter than you need. Get one without an alarm. The one in my truck has a piercing alarm that sounds if you leave it on without the car running.