After the input from jp52 I started researching lithium batteries. There are 6 different kinds. I came to the same conclusion - the LiFePOP4 technology is probably the all-around best choice for kayaks. But even with that there is differences between LiFePOP4 batteries. Big differences in pricing for the same battery.

After looking into it, didn’t like what I found, wrote off the Dakota Lithium Batteries. I’ll leave it at that.

I found 9, 12 and 20Ah LiFePO4 batteries that I like a lot. Who knew there were small “smart” batteries out there. Those things will Bluetooth connect to an app (free) on the phone with batt status, volts, output current, temp, cycle life, event log, battery health. They also have a safety feature I like, monitoring circuitry will shut down the battery if there is a short, then automatically re-energize when corrected. All built into a
 little battery. On the downside, if the Bluetooth is always on it could run the battery down if not on a battery tender.