I was lurking in the EMG Q&A page just for a little research and I found this:

What happens if the battery runs out?
We were afraid you were going to ask... Because EMG pickups are designed from the
ground up to operate as active pickups, they’re not very functional when deprived of
power. As the battery weakens over time, the output level will reduce and become more
distorted. When you hear that happening, it’s time to change the battery.
Below a certain voltage, the onboard active circuitry will stop working. At that point, you
will hear little or no output from the guitar. Don’t let this happen to you!

does that mean if the battery runs completely out they aren't usable anymore? if that's case that means a -30 points in reliability for them, imagine if you travel and forgot to unplug the guitar cable

EMG's experts point me in the right direction if I'm not understanding.
seriously that gives me more reasons to prefer duncans
...You can replace the battery. It's a standard 9v.
Did you miss the line where it says "time to change the battery" ?
lol, that was stupid sorry but I lack experience with actives; question answered you can lock this