I have one. First, they don't use 9-volt batteries - they use 4 AAs. And they will eat normal alkaline batteries for lunch - but it wasn't designed for them
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Fender recommends 2600-2700 mAh rechargeable batteries and say they will get 9-10 hours. I use Kodak 2400-2500 mAh ones, and they get 7-8 hours. I have 2 sets, one in the guitar, and 1 getting charged, which takes about 3 hours or so. I've never been without working batteries. It would have been nice to have an external
ON/OFF switch, but it's hidden - just disconnect the guitar cable at the guitar end.
And if you do run out of juice, just turn the Mode switch to N, and it's just another American Strat - but with only 1 tone knob. Of course, it's just a Strat then - nothing fancy.
I like mine - but I won it from Fender, and my only cost was the charger and and a second set of batteries. It's not a bad guitar, it's just that it doesn't have many features in actual fact - yes, it has multiple different tunings, and multiple guitar types - but since you can't change them to anything else, many folks are disappointed. As far as I can tell, Fender wanted to make something different - but not too different, so the actual synth is not documented, and it's various ports don't have any way out of the guitar to some other box. They wanted it to be robust enough for stage work - and lots of small (or big) cables running out of the guitar would be the exact reverse of that.
Just my 2-cents,
Gil