I have switched to my own 3D Printed case with 2 removable 18650 Lithium batteries and discharge protection. The disadvantage, the case is about 1/4" fatter. The advantages are that I can have charged batteries in place in seconds. This set up last a LOOONG time compared to the nickel batteries before recharging is needed. You can recharge with an inexpensive Lithium USB charger that works for a bunch of other types of batteries also.? The batteries are larger but MUCH lighter. The BIGGEST advantage was that I got to have a fun project. If you are interested, I have posted my work on Thingiverse.? If you have access to a 3D printer and a soldering gun, you can make this.?