Or, you might consider buying something like this: Sears: Online department store featuring appliances, tools, fitness equipment and more plus this: Sears: Online department store featuring appliances, tools, fitness equipment and more and stick with the AC-powered gear you may already have.

I searched that product you mentioned, and I'd save my money for something decent.

First of all, it's only 20W (and how they arrived at that wattage rating is always suspect for Korean-designed/Chinese-made cheap stuff). It's got an 8" speaker, of what quality...I don't know.

Guitar, vocals AND electric bass going into a small battery-powered 20W cheapo? I'd wager it's not gonna sound good, clear or loud enough to impress anyone down on the noisy platform of the Tube! Look up the specs. Even with what they call a 'tweeter', the high-end range limit is stated as 12kHz. I guess that makes sense, because the "Treble" control is claimed to be at at 2kHz...more like midrange. SURE..let's turn up the "treble" to increase the 'shshsibilanshshshsh' that lives somewhere between 2kHz and 12kHz! I can guess pretty lifeless, dull sound with that thing, with plenty of farting distortion with a bass added. May be OK for your bedroom at low volume, but I doubt it'll be pretty on the average street corner. It seems to be some cheezoid off-brand, and that's rarely a good investment.

Even if you decided to buy a better battery-operated one from a reputable company, I'd tell the bass player to get his own so his low-end histrionics aren't burying your guitar and vocals. Most decent units of that type will usually do a decent job of running a guitar/vocal mix, though. I'd get more power, if I were you. 20 watts of questionable quality is not something I'd rush out and buy, and I certainly wouldn't expect it to sound anywhere near decent. You might, however, use it to get people to pay you NOT to play through that thing! "EEEKK! I'll give you a pound if you'll just turn that thing OFF!"

Just sayin',

Kapt.Krunch

Why not get this:
[[url=http://[/URL]="http://www.sweetwat…"]Roland KC-110 | Sweetwater.com[/]="http://www.sweetwat…"]Roland KC-110 | Sweetwater.com[/]
3 channels, Mic input on channel 1, instruments on channels 2 & 3.
Uses 8 AA batteries, has effects in stereo!
Perfect little street amp....it will sound nice too!
Roland makes good stuff...
Is this going to be like two people...guitar/vocalist and a bass player?

Battery powered amp

Hi, yeah will be me on guitar/vox and bass player. Although the bass player can sing too which did really want to get going at same time as all other instruments. Thought about using a "two into one adapter for the guitar and bass, thereby freeing up another channel to plug the mic in via normal jack input. Was also thinking of using a foot stomper to put a bit of percussive drum sound in the music, again via a jack input. Doing a lot of chin stroking trying to work out best option for the smallest price!!!! Ideas?

The electric bass guitar is going to be very taxing to any battery operated system. For example, sometimes you see a marching band with a bass guitar or electronic keyboard. They tend to use a sizable cart with and sizable amplifier run by a big power-inverter using deep-cycle truck batteries. This gives the bass enough volume to compete with the brass and drum line - but only has to run 30 minutes at a time for a typical half-time at a (an American) football game. For long parades they will often have a support vehicle, which provides 12v to the inverter / sizable amp.

Is an acoustic bass guitar out of the question?

If I was working with 2 good voices, guitar, & bass - I'd be inclined to amplify the voices and try an acoustic bass. It doesn't have to be an enormous upright bass. Although those are really cool, they might be cumbersome.

But maybe your electric guitar approach might set you apart from the rest of the street-entertainers - I'm sure you've given this much more thought than the rest of us.

Best of luck!