I know there are options with more power/features etc- but for my celestron cpc800 I went with a cheap small lithium pack. I got it off eBay for about $70.
Does me about 3-4 nights visual, or 4hrs running an eaa setup (scope, asi294mc uncooled, ASIAIR pro, dew heater. I’ve never had a problem with it in about 12mths but for eaa if I had my time again I’d go a bit more capacity.
It’s small and light enough I Velcro it to the side of the mount.
https://www.ebay.com.au/itm/Portable...154756-20017-0
Just my 2c…