What size starting battery do I need?

[poconojoe]

The boat is a 2003 Bayliner 185 bow rider with a 4.3L Mercruiser (Carbed, 190 HP) and an Alpha 1 Gen 2 outdrive.
I'm the third owner and don't know what the factory supplied as an original battery in 2003.
Looking to buy a new starting battery and want to buy the proper size, not just match what is existing in the boat.
Currently I have two batteries with an ACR and Perko 1-2-all-off switch. One battery is dead. I don't know the age of either battery.
I just basically use the batteries for starting the engine. (I keep two for peace of mind) Very rarely play the stereo. I like the sound of nature better!
Physical size I will determine by what fits in the existing battery box.
But, how many CCA should I purchase?
Thanks,
Joe

 

[Georgesalmon]

The proper size is the most CCA that will fit in the box. The motor will only draw what it needs. You don't want to get caught on the water with a hard starting motor some day and not have a little extra. Another case where bugger IS better.

 

[gm280]

I have to say that I have a '98 Blazer with the 4.3 engine in it. And they installed the smallest battery one could imagine in that vehicle. However, it has never ever failed to crank that engine. So with that info, most any size would suffice, IF that is all you have connected to the starting battery. If you have other things running from it, then go the biggest you can stuff in there. JMHO!

 

[ondarvr]

Just went through this with a good friend, we were out battery shopping for his 23' boat with a 200 Yamaha on it. He kept asking me what size battery to get, my answer is always the same, get the biggest most powerfull battery that will fit in the space provided. He decided that the best route would be to buy the least expensive battery that met the CCA needs for the motor, which was small and cheap.

This took place about 4 weeks ago, he just called yesterday while he was returning the battery under warranty because after leaving a couple items on for a short while the battery would be dead and not start the motor. The battery checked out bad due to being discharged too many times, even though it was only over a short period of time. Luckily his kicker motor has a charging system and he could start the kicker and eventually start the big motor.

He didn't say if he was going with a bigger battery this time or not, but he always buys the least expensive gear he can find, then ends up replacing it when it fails and then complains about the quality.

 

[NYBo]

The starting needs for that motor are fairly modest. Even the smallest marine cranking battery will work fine. Note that if you do a lot of starting without a lot of run time, the alternator won't keep up, and you should use a battery charger at the end of the day to maximize the life of the battery and to prevent a no-start situation the next time you use the boat.

 

[UncleWillie]

While it will be hard to find a battery that will not work....
For the 4.3L engine, Mercury Specs a Minimum Recommended Battery Rating of ...

550 CCA, 850 MCA, 150Ah