This view provides perspective on the location of the battery box in the hatch. Hatch still provide plenty of room for storing cart wheels, waders, and other cargo.
Notice the terminal strip on the front, the power switch on the side (prevents charger power from reaching the fishfinder), the 1 A fuse, and charger plug (on right top). Inside are 6 V, 7 Ahr alarm batteries connected in series to provide 12 V.
The battery box is an inexpensive container strapped to the kayak using a 1/4" nylon cord tied around the scupper "pillars." Transducer is mounted to the hull using marine goop in a 3" PVC protective shielding.