I have been wanting to create a lighter waist belt assist with a smaller size box. I found some of the newer 21700 cells have made this possible while still getting a decent runtime.
Using Linkdata 65p cells I made a 12s1p battery and then designed a 3d printed housing to accommodate the battery with the receiver inside. I fully potted the battery and receiver inside the box for waterproofing with epoxy resin. A Sequre WP14200 esc is mounted on the top side of the box and is removable if needed. I used a Cnlinko waterproof 14 pin connector to allow access for cell balancing. The box is mounted to a waist belt from amazon.
I usually ride my integrated foil assist prone board setup and have a dedicated diy mast with an integrated motor. To make this mast work with the waist belt system I made an adapter plate that plugs into the mast baseplate using a MR60 connector.
First use was in flat water efoiling and I was able to ride 30 minutes continuously on the battery down to 3.2 volts per cell. I used it for the first time in some windy surf conditions yesterday and was able to ride for 36 minutes.
Total weight without the mast is 5.1lbs
I was able to get the sequre 14200 programmed correctly after having some issues with the stock am32 settings. The issue was the motor KV was set to 2000kv and I am using a 105kv motor. This was limiting my RPM severely on my initial testing. Appreciate everyone on the forum helping out with getting this issue sorted. 
