FF Battery question (ryobi Lithium Ion?)

[ProfessorLongArms]

Hey All,

Had a great day on the water today, (The calico bite was so good, I could barely make bait... had them load up my sabiki twice, which was a fun and new challenge) but my battery went out prematurely on my FF.

This will be the 4th SLA battery I've bought since getting my Kayak 3 years ago. I'd noticed last night that my backup and my main weren't holding above 11.9v and had a feeling it was becoming problematic.

One place I *have* had a great battery experience is with my tools. I've spent half my life on jobsites, and seldom have to replace a Ryobi battery. It hit me today that they're the same Amp hour rating as a Nocqua (5ah on some of the aftermarket ebay batteries)

Am I missing anything? Anybody tried this before and have tips/warnings, etc?

EDIT: I'm an idiot and should refrain from thinking after a day on the water... I realize my Ryobis are 18v. . . . But I do see stuff like this online that looks pretty tempting for the price if nothing else worth the experiment
https://www.amazon.com/DSANKE-Lithiu...673836&sr=8-16