I just worked through this myself. Get on YouTube and watch this Tiny Boat Nation video (/https://youtu.be/kfRrqUSceV8?is=WNUTH3eZbfVBWNQ9/) for a breakdown of the characteristics of lithium batteries. It has a clickbait title but has good information. After you know some basics, go to the Will Prowse Off-Grid Solar channel and see if he has a teardown of the battery you are interested in. His interest is solar systems, but he nerds out on lithium batteries. Honestly, if he doesn't have a teardown video, I wouldn't buy that battery.
Now for the rough breakdown as I understand it.
Only consider LiFePO4 batteries. I didn't see others, but I guess older technologies were more prone to thermal runaway (nothing exciting, just all-consuming fire, etc.).
The premium batteries like Dakota are great products with excellent support. You can buy peace of mind if you can afford it at $700+.
The cheap $150-160 no-name batteries are almost definitely grade C cells (the equivalent of the old "grade E but edible" beef they used to use at Taco Bell). You will find a Bubba that swears by them online somewhere, but it is more of a dice roll and support will probably be sketchy if/when you need it.
The current "just right" option by popular consensus seems to be LiTime batteries. They perform well, their construction is solid using good components, and they have good customer support if you have issues. They run $325-375.
You want the amp hours of the battery to be higher than the max amp draw of the trolling motor (this is good to look up for familiarity, but a “small” trolling motor should be well under 50 amps). Your described use (under 4 hr total run time) should only require a 12V 50ah and should be cheaper than the price points I listed above because I was pricing 12V 100ah batteries. However, LiTime makes an Xtra Mini 12V 100ah that weighs 19 lb. that kayak dudes love because it is so small. I'm not sure of the specs of their 50ah batteries, but they were around 12 lb. and $225 IIRC. I ended up getting their 12V 100ah trolling motor battery because it is supposedly optimized for trolling use. I grew up draining batteries wind and tide and will always err on the side of more battery than necessary.
Every source advised me to get the smart battery with the BCM that links to an app on your phone that monitors charge. This is important because lithium batteries don't drop voltage until they are 80+% drained, so if you use a conventional voltage meter to track usage, you will already be decreasing service life of the battery before you even notice any power drop.
Also note that you need a lithium compatible battery charger. Your conventional charger may damage a lithium. I had to buy a new one.
Nate
PS Taco Bell doesn't serve better beef these days. The nomenclature of the grading system changed since the 90's.
