Inexpensive, Light, Long lasting (High amp hours).
Battery tech really hasn't evolved much. If you're planning on deep cycling a battery, you're going to want a marine grade lead acid, which means HEAVY (duh, Pb).
You could do a NiCad, but for a good one that will recharge and give you good lifespan, you're going to fork out the $$$. Really, don't even consider Li-ion, if you deep cycle them, you kill them. They also run hot if you discharge them too quicky, and CAN burst into fire.
Honestly, you're already on a small boat (the PA), might as well get a good long charge holding deep cycle marine battery.
Edited by APynckel (04/08/16 10:35 AM)