I need to replace my cranking battery and i believe the current one is smaller (Group 24) than what came from factory.

Do any of you know that the recommended battery size is for a Ranger 186 VS with a Merc Optimax 175? (I bought the boat used.)

if it will fit go group 31, I don't have a bass boat but the 31 sure works much better

Any size as long as it has the cranking amps and just about anything is going to star an outboard. I think bigger is better and there's no reason not to use a deep cycle battery for cranking. If all of your batteries are the same type and size they can be rotated and you'll get a little more longevity out of them. The so-called marine starting and"dual purpose" batteries are not going to hold up well under trolling motor use. That's why I use true deep cycles for everything.

Thanks Bill and Bob.

I just had a "DUH!" moment. The battery tray, which is original, has a "Group 27" embossed on the surface of the tray. Still might do what Bob says and get the same battery as my trolling motor bank.

Check engine owners manual for recommended start battery size/amps requirements.

You can't always go by the markings on the battery tray as a lot of them are generic and will hold different size batteries. You won't get in trouble going with larger batteries, but the Group 31s will get a little heavy when you start moving them around.

i believe that engine requires a 1000 amp cold cranking battery. i use a 27 deep cycle battery from interstate batteries.

The boat and the outboard motor will work fine with a 500cca but when Sirius radios and new electronics get installed, amp draw requires 1000cca or larger. Have put some 1200cca battery`s on and some dual cranking battery`s just to satisfy the amp draw.