The AE-1 battery pack can be replaced. To do so requires sliding the PCB
out of the chassis, inserting the battery and plugging the battery pack
into a connector on the board.
Like any rechargable battery, whether it be individual NiMHs or Ni-Cads, or
laptop batteries, Mp3 player batteries, phone batteries, they all have a
limited life, typically rated at 500 cycles - however, the battery doesnt
just stop working at 500 cycles, typically this is a point where maybe
they'll only hold 70% of their original charge, and the battery life would
lessen.
Assuming the battery works perfectly through 500 cycles, and the amp is
left on 100% of the time, the battery pack would last 62,500 hours or 2604
days or more than 7 years.
HeadAmp will be offering additional battery packs for anyone who wants one for only about $15-20 each. The battery pack will be covered under the 2 year parts & labor warranty included with the amp.
FYI I am in no way affiliated with HeadAmp. I am just a former GilmoreLite+customPSU owner who was very satisfied with the product (and interested in this one).