I have a 3 year old 35US$ Ub12180, a chinese AGM
When i first got it it by itself had enough CCA( barely) to start a overnight cold 5.2 liter v8 engine in warm ambient temperatures
recently I used it to power, through an 12vdc 800 watt MSW 115vac inverter
A 4.5 amp 'buckethead' shopvac, for several minutes
A 9 amp leaf blower, on the low setting.
The buckethead is drawing about 32 amps from the batteryt
The leafblower was drawing ~38 amps.
I was able to use both, for as long as needed, several minutes, and the inverter
starts alarming at 10.49v but does not cut out until lower.
I use 45 amp Anderson powerpoles on battery and inverter and 8awg.
I've exceeded their 45 amp rating, many times, and some of those times were about 60 amps for 15+ minutes, but I stuff 8awg into them, they say 10 awg max.
The Ub12220 is a 22Ah AGM
and the same exact size as the Ub12180 @ 18AH. The Ub12220 weighs about 3 lbs more.
If I had deeper pockets I'd get one of Odyssey Agms powersports batteries, but honestly these cheap
chinese AGMS have met my requirements as a portable 12v power source.
The 3 year old 18 ah one has been a bit weird in that when charging
, watching amps taper at 14.5v, they will often stop tapering and start rising in the 0.3 range. I have to let it sit, rest and start applying 14.5v again, and then amps they might taper to 0.09 before starting to rise.
The 2 year old Ub12220 just tapers to near zero at 14.5v and amps never start rising again.
With the automotive lithium jump packs, often their capacity is marketed in mAH, at 5 volts DC, or perhaps the lithium cell capacity at 3.4 or 3.7 volts.
The Lithium jumperpacks have impressive engine starting abilities, but their capacity, in terms of powering 12v items for extended periods, will likely prove disappointing.