Question about suitable battery type

[alan-bc]

Short version: what kind of battery is OK to use with a 2010 Mercury 4 stroke EFI 50HP?

Long version:
I have just purchased an older 15' Boston Whaler powered by a 2010 Mercury EFI, 50 HP.

The previous owner seemed very concerned when I told him I planned to launch it the minute I got home, telling me that "maybe you should pick it up tomorrow; that will give me a whole day to charge the batteries".

I took this as code for "the electrics were sketchy". So rather than launching immediately, it went to my driveway, whereupon I dug into the electrics.

The short story is that I'm about to replace every single piece of wire, and everything at the ends of the wires; switches, lights, gauges, everything, as everything is corroded!

And while I'm at it, I'll replace the battery, as who knows how old it might be (no date codes on it).

The question that I can't seem to find an answer to is what kind of battery can I use? I'd rather not use a plain old lead acid wet cell, as the location of the battery makes inspection/top-ups nearly impossible.

I'd like to use some zero maintenance type .. AGM, for example. But I want to be sure the motor will charge it properly, neither over nor under.

Thanks for any thoughts.

 

[dingbat]

The owners manual will give you the min. CCA requirements for the battery.

From there it depends on how much room you have for a battery. Bigger is better but only to the point that you can keep the battery charged.

I’ve had good luck using deep cycle RV batteries. They met the min. CCA requirements for my motor and they are maintenance free.

Just keep them charged…..

 

[alan-bc]

The owners manual will give you the min. CCA requirements for the battery.

From there it depends on how much room you have for a battery. Bigger is better but only to the point that you can keep the battery charged.

I’ve had good luck using deep cycle RV batteries. They met the min. CCA requirements for my motor and they are maintenance free.

Just keep them charged…..

Thanks for the reply!

Sadly, the ONLY mention of "battery" in the manual says "The battery should be inspected periodically." There are no battery specs or requirements at all, which I find unusual. ' But I'm not too worried about the CCA spec; if it can start my diesel truck, it can start a little outboard.

My concern is chemistry.

You see, the charger on my sailboat has a switch for flooded or AGM, and the manual cautions that it must be set correctly because "the wrong setting can result in the battery being over charged or under charged."

Since an alternator also has charging circuitry, I'm curious as to what sort of battery that circuitry is designed for.

 

[dingbat]

My concern is chemistry.

You see, the charger on my sailboat has a switch for flooded or AGM, and the manual cautions that it must be set correctly because "the wrong setting can result in the battery being over charged or under charged.

The motor is charging the battery with an alternator, not a charger.

To “top off” the AGM you must follow up with a battery charger designed for AGM use.

I choose not to deal with that nonsense and run flooded acid batteries.

My last pair of grp. 27 batteries lasted 10 years @ $125 each

Looks like you need 465 CCA

http://www.dekabatteries.com/assets/base/0406MarineApplicationslayout.pdf