Mercury 280 Cranking Amps

[MUFC777]

How many cold cranking amps do I need for a 280?

[Go Time]

700-800 will do just fine.

[MUFC777]

Thanks. Being my boat is wired with two batteries should they both have 700-800 cranking amps.

[Go Time]

That would be best, as the object of two is that either can be used if one were to fail.

[luv2gofast]

I guess it depends on how you use your boat. If you start it and run for 15 minutes that nice big alternator will have your battery charged back up full. In that case you could probably get away with 100 CCA. I'm sure some of the racers can tell you what the smallest battery you can get away with is. If you have two batteries, it won't matter what they are for the 280. It's all about what else you expect to run off of the batteries when the engine is not running. I have always run a single battery and never worried about the CCA but I watch how long I run the crankin' tunes with the 1000w amp while sitting on the beach. I have thought about adding a very small battery that would have just enough to start the 280 and separating it from the main battery for accessory drain. That way I could kill the big battery and still start the motor which would charge both batteries back up on the run home.

[MUFC777]

I don't run anything else off the battery just the normal stuff. No stereo.

[h2oskiier30]

Pretty sure the manual from Merc states minimum 350CCA's for a 280.

[Go Time]

350 minimum is correct for the 280.....300X is 700