Ok I have a dead battery, In anticipation of Lithium when my charger went out I picked up a Minnkota 4 bank capable of charging LI batteries. Now that the AGM has given its all, what do I go with? There are hundreds out there. I don't fish enough to warrant $800 bucks per batt. So in the low to mid range what should I go with? Ranger z520 2008 with an ultrex.