Pb Powerbank

In preparation for being off-grid for a few days, I quickly built this ‘power bank’ around a 12 V 7 Ah lead gel battery. The circuit is simply pushed onto the battery’s 6.3 mm contacts and provides 3 USB ports. Charging circuitry is not included but the battery terminals are still accessible anyway.

The switching regulator around a MCP16322 is as basic as it gets. A dual comparator adds a deep discharge protection and a overcurrent shutdown.
The overcurrent shutdown was, however, a bit over-sensitive. After trying to fix it with additional ground connections (the layout is only single-sided and thus suboptimal, after all), I finally disabled it by shorting R10. The buck converter is still protected by its current mode operation.

KiCad schematic and PCB layout can be found here.