Battery QuestionI have a 2004 260...

[Lifeguard]

Battery Question

I have a 2004 260 Sundancer that I recently purchased. I have what I believe to be an odd battery combo, and one is dead so it is time to get new batteries. According to Sea Ray the 2 batteries should be of the same style size and age. What I have right now is one deep cycle battery (the dead one) and a car starting battery (the newer/still good one). I am planning on replacing both. My question is this:

• What type battery is best? 2 deep cycle (can I start the engine with them) or do I need a combo?
• SR says the batteries should be group 31. Is this critical, or can I use a slightly different size?
• Do you have a favorite brand/type?

[gregk]

I use a dual purpose start/deep cycle group 27. If you don't leave the battery switch on both, you can mix old and new batteries.

[gregk]

I like Napa batteries, typically get 5 years out of them.

[Steal_Away]

I highly recommend Interstate 31P-MHD batteries. They are fully sealed. Have most recently used 4 of them on my 2012 370 Sundancer with no issues.

[Scott3262]

Same as gregk, 27. Bought at Sam’s Club, both are the same.

[Lifeguard]

Thank you for your insights, much appreciated.

[lance]

If your boat has DTS use what ever Mercruiser recommends. The computers are very sensitive to amps. If you do not have the correct amps it will trip off alarms in the smart craft. I had an alarm going off I couldn't figure it out until I brought it to a certified Mercruiser mechanic. I had 1 battery with 1 dead cell. The voltage was fine but the amps were not. Get there recommendation

[Korkie]

Replace with 2 of the same. Suggestion is check the specs from Mercruiser and put the same thing back in. They are probably Group 27 AGC. Yes the Deep Cycle will start your boat. Most importantly replace both with 2 new. An old battery with a slight issue or of a different type will kill a new battery in a matter of weeks.