The battery is a talentcell.com YB1206000 6Ah 12v rechargeable pack. I've got a splitter that comes off of it to run the USB charger and the router. This thing will run the router and charger for days, before it needs to be recharged.
The USB charger is a Yeeco DC Buck Converter Step Down DC-DC 9-36V 12V 24V 32V to 5V Voltage Regulator Converter Volt Transformer Board Power Supply Module with Protective Shell. This will work on voltages from 9-36 volts. I chose this one for the 2.1 x 5.5mm power plug. This is the same plug that the MikroTik router and the battery pack use. Makes it easy to plug everything in using the same cables.
The router is a MikroTik hAPac2. This provides 5 gig Ethernet ports, a 2.4GHz radio and a 5GHz radio. The two radios are split between the inside network and the outside network. I use the 2.4GHz for the outside network, which connects to the coffee shop network. The 5GHz radio and Ethernet ports 2-5 are on the inside. Ethernet port 1 is reserved for connecting to a wired Internet connection. Currently I switch the outside interface on the NAT configuration. A better way is to create a bridge that has both wlan1 and eth1 as part of the bridge. That way it will use whichever interface will get the traffic to the Internet.
Once connected, the router will establish a PPTP VLAN tunnel back to the office. I know that IPSEC would be better, but PPTP works really well when one end of the connection has a dynamic IP address and is behind a NAT router. Biggest problem is that some locations block the VPN tunnel.
With the ability to save the router config to a file, flatten the router, and use it for another purpose, this has proven to be a very versatile to have on the road.