Well, as a UK resident I thought I'd got my Taylor battery supply sorted about a year ago. I got a dozen 'Made in USA' Duracell Coppertops from Battery Junction (US company - got a friend who over-winter's in Florida to bring them back for me).
A month or so ago, I needed to re-order but Battery Junction no longer stock the 'Made in USA' version. Found some on Amazon.com and ordered them. They took a month to arrive and the packaging had been opened and re-sealed and 3 batteries were missing (bizarre??!!). (Got a partial refund from Amazon without any problem, but I'm concerned about future supplies).
I Googled 'Taylor guitar batteries', just as an idle gesture and the result was 'Guitar Mania', a Taylor dealer fairly close to me. They are saying that you can't get the Duracell 9v 'Made in USA' batteries any more, as they've stopped making them (not sure if that's just Europe or US as well). They now recommend and sell Energiser Max batteries. They quote dimensions which are slightly smaller than the standard, which is fine on the face of it, but when I search the batteries on other sites, the dimensions are standard (ie, slightly larger than quoted by Guitar Mania). I know the shop and I can't believe they'd get it wrong, so I wondered if anyone on this Forum has experience with Energiser Max in Taylor guitars?