Rechargeable NiMH batteries have a longer life, are kinder to the environment and cheaper in the long run. A 9v squarepack or 4xAAs cost about GBP8, say USD11, and should recharge a thousand times, or so they claim! Of course, you need a charger, but with the increasing use of digital cameras, even these are getting cheaper.

I have two Washburn semi-acoustics, one needs to have its battery replaced through the soundhole, so I replace it each time I change strings with a newly charged battery. The other has a later Fishman installation, and has a little trapdoor by the tailpiece for the battery (and a little LED to tell whether the battery has reasonable charge), so I carry a spare.

So much for being unplugged!!

Alan