What size battery

[UncleWillie]

Are you sure it is wired correctly?
There are two power paths to the ignition coil.
One path supplies reduced power to the coil through a ballast resistor whenever the key is ON.
The other supplies full 12v power through the starter only while cranking.
If it starts and then dies just as you release the key, the the ballast supply has a problem.

 

[H20Rat]

If it cranks the engine and the engine fires and dies; it is NOT a battery problem.
If the battery will crank the engine for more than 30 seconds, it is plenty large enough.

1 CCA per cubic inch sounds like an awfully small battery.
Mercury recommends my 4.3L Merc, 262 Cubic Inch, at "Minimum Recommended Battery Rating : 550 cca / 825 mca / 150 AH"
More like 2 CCA to 1 Cubic Inch. or 3 MCA per inch.

Guess it depends on what the mfg feels like that day. My RV has a big block ford 460 in front, with a little group 24 battery box. Manual recommends >450 CCA. RV's and boats generally aren't used much in the winter, so CCA's requirements are lower.

 

[bruceb58]

Mercury recommends my 4.3L Merc, 262 Cubic Inch, at "Minimum Recommended Battery Rating : 550 cca / 825 mca / 150 AH"
More like 2 CCA to 1 Cubic Inch. or 3 MCA per inch.

150AH? That's a huge battery! Maybe you meant reserve minutes.

BTW, Volvo recommends 360 CCA for 3.0 and 4.3L engines and 660 for everything else.

 

[UncleWillie]

150AH? That's a huge battery! Maybe you meant reserve minutes...

That was a cut and paste from Merc Manual #32, page 1B-4
Not sure what they meant, but the boat came with a Group 27 battery to crank a 4.3L mpi engine.
It cranks with authority and starts with 2 revolutions every time.

 

[bruceb58]

That was a cut and paste from Merc Manual #32, page 1B-4
Not sure what they meant, but the boat came with a Group 27 battery to crank a 4.3L mpi engine.
It cranks with authority and starts with 2 revolutions every time.

Even a group 27 battery wouldn't be 150AH. Wonder what else is wrong on that line.