This is what I built learning from Youtube (Thank You JDS OUTDOORS) It's 3 batteries 12VDC 15Ah each gives me 45 Ah total. It has 5Vdc USB plugs for phone charging and a 12VDC socket for my small ac inverter if ever needed? Then I added 4 power posts and here's where it gets cool! In that circuit I added the DC to DC power supply that allows me to step up to 13.8 VDC and hold that evenly until I think the batteries drop below 9VDC? Will have to test that? The plan is running 3 scanners BCD536HP/BCT15XT and Pro 2035. At the same time have a Rasberry Pi for Stratux ADSB running for aircraft tracking. If the Ipad goes down I can charge that up as well. Added the LED's for a pathway light or camp light. Cool project!!