UPS (Uninterrupted Power Supply) to the rescue.
I use them on my PC's. They maintain a clean voltage, and in brownouts and blackouts, they provide full power to continue playing, but the time is limited, and that limit depends on the model you buy and how much you want to spend.

I wish they had them years back.
We use to play some dinner/cruise jobs.
I was using a transistor/electronic accordion and the power regulator (of the ship) created a brownout and my system would shut down, off and on. It happened over and over thru the night.

I should have stuck with my old tube-type accordion. It would have played but it would have been out of tune, and the others would just have to retune their instruments and vocals to follow me.

On the UPS, if you shop around for 1, see if you can get 1 that does not sound a warning beep when it kicks in. Mine do.
but the beeps are when the power has actually been interrupted, in which case, in your situation, a little beep won't be heard over the screaming dancers and the sounds of faces being slapped in the dark, and hearing things like "get your hands off me"



[This message has been edited by MrEd (edited 08-19-2006).]