It was annoying for me to swap batteries in the dark on a ride back from work (original battery pack 4×18650 is slowly dying…), so I came up with idea of making double battery from storage container. Actually to be honest Steffano’s problem inspired me. I used 6 pin toggle switch grommet for 3mm cable, 2.1mm connectors (I wanted to be able to use battery pack same way as originally designed), pro 500ml container. Short story below in pictures. Thankfully my soldering isn’t visible ;-). Basically I’m able with one flip of a switch swap between second battery pack.
Keep’em rolling. (in the dark)