Check out ZPro Lithium out of Austin. They just rebranded. They were Ampowsure Lithium. I've been testing for almost a year with no issues. I like that they are local and readily available. Owner is literally a battery scientist
I can 2nd these. I have been using them for 8 months or so as well. Using 3 100ah 12v on my ultrex. Not an issue, run forever, no dip, and have forgotten to plug them in without suffering the dreaded no trolling motor due to dead batteries.