[areastwood]

I have a Center Console Gheenoe Classic with an electric start, 25 HP 4 stroke Yamaha. I am installing a Riptide RT50. I could use some input on the battery slection. Should I go with a a single Dual Purpose AGM battery (been looking at the Odyssey 31M PC1500 and 34M PC2150) or should I install a separate battery for the trolling motor and keep my cranking battery? I like the single battery since it saves wieght over 2 batteries. Any input would be appreciated.

 

[tom_in_orl]

I have basically the same setup except a 2 stroke. I have been using a single AGM Group 27 for 18 months now. The only reason I would consider two batteries is if my motor didn't have a pull start for backup. Does the 4 stroke come with pull start?

 

[areastwood]

It currently doesn't have a pull start. It would cost $300 to put one on which is prohibitive. I was considering geting a small 12V motorcycle or lawn tractor battery to use as a spare?

 

[tom_in_orl]

That should work. I don't have personal experience trying it but a motorcycle battery can crank big v-twins so a 25 hp boat motor should be no problem. Also consider a battery switch so you can move back and forth in case one dies.

West Marine Battery Switch

 

[Eric_S]

That should work. I don't have personal experience trying it but a motorcycle battery can crank big v-twins so a 25 hp boat motor should be no problem. Also consider a battery switch so you can move back and forth in case one dies.

West Marine Battery Switch

I do not advise using a motorcycle battery for marine applications. Especially without an alternator, which they are specifically designed for use in conjunction with. They can apply a specific amount of power for a VERY short duration of time without necessary charging from a running motor. They also lose charge very quickly. That is not a good scenario in a back-up battery.

Now, I believe that the Optima Yellow-top is a dual purpose Crank and Deep-cycle battery. In know that the blue is deep cycle, and I have a Red-top in my car. From my experience, they do not produce power for nearly as long as a traditional deep-cycle. Also, I agree that you may find yourself UP SHIT CREEK (literally) if you run the trolling motor all day and find yourself unable to crank the battery to get home.

If you really want to use a two battery setup, I would look into something called "traction batteries". They are essentially SLI and AGM batteries with weight in mind. Braille is the most popular brand of these, but there are others out there, especially for aviation applications. They will allow you to run two batteries with none of the extra weight. I think that the braille group 65 weighs 11.5 pounds.