I dunno, Paul... to get four hours out of a motorcycle battery....

Let's say it was rated at 8 amp-hours. That means if you drew only 24 watts to run the whole thing, you would completely exhaust the battery in four hours, except of course by the time you'd run it for three hours the voltage would have dropped to the point where either the empeg or the amplifier would have already quit.

An empirical way of looking at it might be to think that an empeg and a decent amplifier would pull about as much current as one of the headlights in your car. How big a battery do you need to keep that light burning bright for four hours?

tanstaafl.

"There Ain't No Such Thing As A Free Lunch"