Just put three 50ah lithiums in my Eyra. I took the top part of the tray and flipped it over and slid it down the rods and bolted it down. Ran straps length wise in between the trays and also across each individual battery to keep them secure. I’ll get a photo and post it. I also put a carpet type material between each battery to give extra protection in rough water. I found this material at Lowes, it kinda looks like a mat of some type. Rubber on the bottom and a carpet type material on the top, it was in strips about 3 feet long and maybe 12′ wide but lots of things would work and maybe not even necessary.
The three 50ah lithiums fit where two of my previous batteries fit plus there’s still a little extra space there and I also have an an open spot next to my cranking battery. I had the Minn Kota Precision charger and it works with the Lithiums just fine.