Paul the best batteries if you want light weight are the LiFePo4 batteries and when you look into the purchase price of them the Bluetti become good value. Throw in the other hardware and they really are cheap.
I have a good battery box but find lead acid batteries both heavy and not the best if accidentally tipped on their side (even sealed top things can leak) and they need to be charged in reasonably vented space.
Then throw in a proper charger for a LiFePo4 and the readily available units are actually cheap. I did the maths because I have a background in electronics and was going to save a fortune until I realised I wasn't.
Though I haven't yet bought a Bluetti but I intend to when I have the finances.
Anyway, just my $0.02:
https://www.cloudynights.com/topic/7...able-powerbox/
https://stargazerslounge.com/topic/2...12v-power-box/
https://kelly.flanagan.io/astronomy/...rophotography/
Google search will bring up plenty of results.
I dare say there would likely already be some here too but I haven't searched this forum, just Google.