Hi,
I know I'm a bit late to this thread, but thought my 2¢ worth might be helpful...
I experimented with a couple of PowerMate supplies - they held their voltage very well, but just didn't have the capacity I needed to run my setup all night.
After a lot of research, I got a Bluetti EB70 - 720WH - it is fantastic and runs my setup all night with 50% to spare.
It was so good I got a second one to use with my smaller rig, and as a backup for my larger one. They are not inexpensive - but hold up at 13v until they are almost completely flat.
Now I use my Powermate as a torch - a purpose it serves very well
