Help with Batteries

[bmmartin249]

I am new to owning a boat and am in the process of restoring an Old 1978 Sport-Craft Adventurer. I've replaced the flotation foam, added a new floor and fixing to install new carpet. Now comes the battery part which I've been thinking about. The old battery that was in the boat was an Everstart Deep Cycle from walmart at 12V 29C with 845 Cranking Amps. My motor is a 1981 115 Mariner. A friend told me that I just need a cranking battery. The terminology is a little confusing. A cranking battery, isn't that just like a regular car battery? The deep cycle would be used more for a trolling motor? Can you not use a deep cycle on both the motor and a trolling motor? Help.

 

[bobeast]

Unless you use power while the engine is not running, a starting battery is just fine. If you like to crank your stereo for hours on end or run a bunch of marine electronics while the motor isn't running, you should consider a dual-purpose battery. They can start your engine AND run your accessories for some time. A pure deep cycle battery is not appropriate for starting purposes.

 

[Silvertip]

Actually lots of folks use deep cycles for starting purposes as well. Consider that a muscular person could rope start a 115 two stroke, a deep cycle would have no issue at all. Batteries for marine use are: 1) Marine deep cycle, 2) marine starting and 3) dual purpose. Any one will work for you but a deep cycle is best if you intend to run a single battery for the engine and the trolling motor. The larger the reserve capacity the better.

 

[fishrdan]

I use an automotive battery for my boat's engine start battery, a Group 27 from Walmart, same battery the truck uses. MUCH better warranty than a "marine" battery and it works just fine. It lasted to the end of the warranty (5 or 7 years?) and I just replaced it last year. If the truck battery croaks, I can swap it over to get back on the road quickly....

I don't use that battery for anything else but starting the engine, and have several others on the boat for the trolling motor, lights, radio, etc. Those are "marine" dual purpose batteries.