That sounds really weird, Ian. I had Fishman Fluence Moderns installed in an Epiphone 6 months ago, and the battery is still not dead! I obviously don't play them for many hours a day, but my point is that your battery should not drain that fast while your guitar is unplugged.

With active pickups, if you leave the cable connected to the guitar, and it’s plugged in, the preamp is turned on, and it’s using the battery, even if you’re not playing it.

If you are the DIY type, you can rig up a switch that sits as the last element in the circuit, or — a much easier option, get a 9V lithium battery from Amazon that has a USB-C port on it that can be re-charged easily.  These are super cheap ($10 or so) and require no modifications to the guitar.  If ESP weren’t so cheap they would ship the guitars with re-chargeable 9V batteries like these.

It did it to like 4 batteries. So I tried some  higher end Duracell batteries, and haven't had an issue since. Been about two months with the same Duracell, so I guess it just needed a better battery.

Its awesome and the evertune is super easy to use. The dang guitar came out of the box in tune and intonated

Thanks, Carl!