Exactly what size starting battery for Yanmar 6LP?

[jms02050]

Long post... It's a funny thing - so much info out there yet I find it impossible to get a definitive answer on the correct size starting battery for the Yanmar 6LP. Figured I'd just pick up another G31 but I can't find Interstate batteries near me and they no longer make the same model that I have.

Seems like no two batteries are labelled the same - kind of like mattress shopping. Even tried Mack Boring but no luck. The Yanmar owners manual says 120 amp hours, but nothing about cranking amps, etc.

Currently have an Interstate G31. Label shows
CCA 950
RC 195

Looking to source a battery locally and the closest store carries Duracell G31s (Dekas made by East Penn that are rebranded).

Specs for their G31 Deep Cycle Marine & Starting Battery are
CCA 650
CA 800
AH 105

They also have a Starting Heavy Duty Battery spec'd as
CCA 950
CA 1170

Appears that the Starting Battery is more suited for the job given the higher cranking amps of 1170 compared to 800 but the the amp hours aren't listed.

Anyone happen to have a Duracell starting battery or know of the final answer on what should be used for the Yanmar 6LP?

[Norseman]

I should be able to help you: Got an 6LP-STE in the basement with a lead acid start Battery and 2 lead acid house batteries.
I am guessing Group 27, but will step on the boat in a few minutes, after I finish my Corona drink, then let you know.
Stay tuned.

[Norseman]

Bingo, here is my start Battery: Bought this boat 36 months ago and the batteries was probably a year old then.
Never missed a beat, very happy with brand, size, performance, etc.

AD032A33-4FE9-4A0D-8D41-FF3C490125F3.jpeg

[RobS]

I’ve seen a conversion factor of 7.25 for ah to cca but even using the grp31 you posted the conversion would be 6.2 so that HD battery would be more than capable.

[jms02050]

Thx all. Happy with current battery but when poking around I noticed it's 8 yrs old. Same with the house 4D so figure I'll replace before launch.