....I was trying to do 2 so I could run parrallel but until I figure out how to configure them to fit with the on board charger I will just replace the one for now

I run mine parallel, with a minn-kota on board charger. I don't know if it's right or not, but no problems so far (knock on wood).
I just tied the 2 batt. together ( pos. to pos., neg. to neg.) and hooked the charger to one of the batteries, like one big battery.