FWIW I have a Nocqua kit that i got from Yak Attack. It has been great so far and its completely sealed. Additionally the charger has indicators at 25% increments. it also connects and disconnects with water tight fittings so that you don't have to use the typical lugs, its makes it really easy and secure. Another option is FPV Power, they are a bit more expensive but again completely sealed and they come in a variety of amp-hour ratings, up to 50ah.

https://www.amazon.com/dp/B00ME3ZH7C...p_mob_ap_share


https://www.amazon.com/dp/B07X2TQFKR...p_mob_ap_share

I bought these two, drilled a hole in the case to put the power cable through and epoxied it to make it waterproof. It's nice because when not fishing it doubles as a regular old battery pack (can never have too many). Only ever used up like 10% charge in a full day of fishing.