Battery for MR3020

I've bought the MR3020 and the thumb drive. Set it all up and it works great. I want to make a mobile setup with it and I'm just wondering what battery packs have people used and how long of a run time did they experience?

I have a few ideas rolling around, but I wanna see what others have done first. This unit will mostly be setup remotely as I live in a rural area. It will probably live in my car plugged in for most of its life. I've powered a WRT54G off a car battery in repeater mode for a week before before it died. But I'd like something smaller and lighter.

I have a MR3040 and it gives 4-5 hours with 2000 mAh. So one hour is about 500 mAh.

So any decent USB battery bank should do, you just have to choose the capacity you need. There are plenty to choose from. I have a 4x18650 Panasonic 3400 battery bank on order. Should give at least 24 hours runtime with some margin.

I just bought a Onn Power Bank from Wally World for $25. It says it's ratted at 4400mah. I'll see how much millage I'll get per charge soon.