Can anyone share a pic of how they are getting the extra battery in there 20xd. I currently have a 24v but need to step up to the 36v do to fishing in heavy current all day for tournaments. I do not want to run 2 batteries and cranking battery. I have 2 lowrance hds 12's and live well pump as well as bilge on cranking now but not sure I can get a fourth 31 series in the boat.