KAellis 0 Report post Posted July 3, 2012 I have a new to me 2006 270 cruiser. I have to replace both batteries. Right now they are both cranking batteries. I'd like to make sure I have enough power for my stereo and gps as well as for my bilge pump if needed. Does anyone know if the alternator / electrical system is designed to have the first battery as a starting battery and the second battery as a deep cycle house battery? Or do both of them need to be cranking batts? Share this post Link to post Share on other sites
stuey4 0 Report post Posted July 17, 2012 I would replace them both with deep cycles. both mine are interestate deep cycle marine batteries. not sure the size though. Share this post Link to post Share on other sites
Dodge06 0 Report post Posted July 24, 2012 The batteries are used for both starting and house. The best thing to do is to to buy Deep Cycle marine batteries as they can be used for either starting or as a house battery. This where the battery selector switch come into play, use one battery at a time on the switch. Select either #1 or #2 as your starting battery and the other as your house battery. When you go to start the boat switch to #1 and leave it there until you arrive at where you are going to stay for awhile then switch over to #2 and leave it there until you got to leave or you run out of power. This way you will have the starting battery available and will not be left stranded. Switch this up each time you go out as this will help keep the batteries at the same level. The altenator will charge both batteries no matter the position of the selector switch, if you leave your boat in the water when you turn the selector switch to OFF at the dock when you leave, the boat SYSTEMS (bilge pumps,stereo memory,C02 detector) stays powered up and it will draw off of both batteries during this time if one of the components needs to work. Hope this helps Peter Share this post Link to post Share on other sites