you definitely need a high capacity starting battery for you Optimax I have run many including my current 250 XS see the info below it may be of some help and for good Mercury info see the BBC.com site this info comes from..... "BATTERIES THAT MEET THE REQUIREMENT"- Updated 3/15
Ok guys:
This data was provided by Mercury Marine's R&D Department.
Although these batteries were tested for use with the Verado Engines, their superior Reserve Capacity Ratings would make them an EXCELLENT choice for Optimax or EFI engines used in a Bass Application!
The batteries listed are ALL AGM (Advanced Glass Mat) batteries, and were required to meet at least one of the following ratings:
-1000 MCA
-800 CCA
-180ah*, or meet the 135-RC 25 Capacity Rating.
*For Optimax models, this rating would be 105ah (and this rating is SELDOM used in the US- recommend using CCA Ratings).
Batteries were tested to ensure that they "met" their advertised capacities also.
All of the batteries listed are heavy- and they are not cheap. However... if you want something you can depend on... a wise investment!
----------------------------------------------------------------------------------------------
(Testing and information courtesy of Mercury Marine Research & Development)
-Odyssey PC1500, PC1700, PC2150 and PC2250.
-Optima Group 31
-West Marine Sea Volt Group 31 AGM (Edited due to change in capacity of Grp 27).
-Cabela's ** (REMOVED as new-updated specifications indicate they do not meet requirements- See notes below- did not meet advertised Capacity Ratings).
-Trolling Thunder TT1175 and TT1370.
-Excide Megacycle (Mercury Brand) MC-31 and XMC-31.
-Sears Die Hard Platinum 34M (PM-2) and 31M (PM-1).
-Deka Sea Mate/Intimidator 8A31DTM.
** During initial testing, these batteries do not meet their advertised cranking ratings. Later published ratings support this (they do not meet the requirements).
-----------------------------------------------------------------------------------------------
Although these batteries were tested for use with the Verado Engines, their superior Reserve Capacity Ratings would make them an EXCELLENT choice for Optimax or EFI engines used in a Bass Application!
IMPORTANT NOTE:
STRONGLY RECOMMEND the installation of a CLAMP-STYLE battery terminal on most of these batteries. This gives you a THREADED connection, that is CLAMPED to the largest/strongest connection point the battery has to offer (and often prevents MANY problems that can creep up down the road).
Example:
"BATTERIES THAT MEET THE REQUIREMENT"- Updated 3/15-marineterminal.jpg
Make ALL connections to the terminal as described below:
Battery terminal connections should be installed ENGINE CABLE FIRST, remaining lugs "Largest to Smallest", and finish off the connection with a Stainless Locknut (do NOT use wing-nuts).
BEFORE INSTALLING A NYLOCK NUT ON A BATTERY TERMINAL: IT SHOULD BE PRE-THREADED ONTO A SUITABLE BOLT FULLY, AND REMOVED FROM THE BOLT (to ensure nylock is pre-threaded, and no abnormalities exist in the nut).
Failure to follow this step MAY result in damage to the threaded terminals inside the battery (and subsequent intermittent or total failure of the battery to charge or perform properly).