I also have the iExos 100, and was looking for a battery pack alternative. Here is what I have and I am very happy.
GOOLOO SuperSafe Lithium Jump Starter GP200 from Amazon, @ $90
GOOLOO 12V Cigarette Lighter Socket Adaptor for GOOLOO Air Compressor and Jump Starter Series, Amazon @$8
DC Car Charger Auto Power Supply Cable,12-24V 4FT Car Cigarette Lighter Male Plug to DC 5.5mm, Amazon @8.50
This jump starter works great. I use my iExos visually, for 2-3 hours at a time, and I estimate I could get 10 or more sessions before recharging. It’s small, lightweight, and I have used to recharge a dead car battery, and it worked perfectly. I place it on the eyepiece tray. I carefully removed the existing battery back from the black pouch, and use the pouch to hold the extra cable and cigarette connector. If there is a limitation, it has only one 12v output (unless you use a Y adapter.)
I am anticipating in the future I may need additional 12v outputs and usb outputs, so I am looking at:
SUAOKI Portable Power Station, 150Wh Camping Generator Lithium Power Supply with Dual 110V AC Outlet, Amazon @$126
Atteched is a pic of my setup.
Vero Beach, FL
Scopes: ES AR102, Meade ETX 90 EC
Mounts: ES iExos 100-PMC Eight, (Using ExploreStars iPAD), Oberwerk 5000 Tripod
Binos: Oberwerk 15x70, 8x40