Here's a budget version lithium battery for many kayak fish finders. I have 2 of the 6 AH batteries and they are solid. https://www.amazon.com/Miady-Phosphate-Lightweight-Replacement-Applications/dp/B07X5G2FFW?th=1

That is a pretty good price . Thanks

I use Dakota Lithium 20 AH battery, Humminbird Helix 7 DI + SI, Power Pole anchor, navigation lights, anchor light, dual usb ports keeps my phone and spot light charged and small led overhead light for night fishing. Fished for 3 days and 2 nights near Rockport on 1 charge with plenty of battery left.
Oh yeah I forgot the Hobie livewell that has it's own battery but it ran down and I had to charge it off the Dakota once. I now use a live bait bucket that I set between my legs when peddling Hobie PA 14 and then set the bucket in the water when relocated, it works better, leaves room for a nice size cooler and I can get my bait easier. Keeps shrimp alive all day no worries.