I recently switched to Lithium because my Lowrance Elite 7TI just would use up the power on the 12v 12ah flooded battery I have. The larger 12ah battery was already larger and heavier than my 10ah one I used for years with a smaller screen size FF. With not providing enough usage time I upped for a 20ah Lithium battery that also came with it's own charger. The price has gone up about $7 from when I bought mine but it's still a bargain at the capacity and price including the lithium charger. I put it inside a waterproof Pelican case that I've used for years with a 12v 10ah battery. The Lithium battery even though it's 20ah is slightly smaller the the 10ah and it weight so little that when I pick up that case I can tell them apart because the Lithium Pelican case feels like it must be empty. If not submerged I think they could be used without a waterproof case.
https://www.ebay.com/itm/12v-Battery...r/143931540152