Battery Size and CCA

[psavas]

Morning!

I bought my boat last month a 1994 280 SunRunner with a 7.4 litre 454 V8. According to a MerCruiser bulletin says it needs a battery of 450 CCA or 550 MCA or 90 amp hour. I am not sure of the battery the last guy threw in there but it seems the engine turns over real slow before actually cranking. My battery has died on me before while trying to crank and if I hook up a portable battery jump the engine will turn fast and start right up. I know this is a carbed engine and requires a little more finesse than an EFI but it seems strange that it turns over so slow. My battery gauge shows good at 16 while running. I have NO problem with the alternator.

Can I put a bigger battery in there or will that push to many amps to the starter?

I would like to fix this problem today as it is going to be almost 90 here this weekend in SUNNY FLORIDA!!!!!

 

[Newman]

Putting in a larger capacity battery won't hurt. The starter will draw what it needs. It's a pull not a push thing. You're best bet is to take the old battery out. Determine what it is and have it load tested. That way you know where you stand. While you're in there check the condition of your connections and cables.

 

[Gary Hill]

+1 on Newman's comments. Just because the guage shows 16 while running, which is a little high, doesn't mean the battery is good.

 

[Shock_Loaded]

I would check the actual voltage output of the alternator while running vs what the gauge reads. If it really is putting out 16VDC you will boil the battery dry.
Other than that, it was all well said above.
Enjoy the nice weekend!

 

[Frankiea87]

hey I have same setup-7.4l merc, I ran last year thinking I had an electrical issue with the boat bc starting was slow and sounded like battery was dead but I always had 12 volts + , this year while I had batteries out I brought them to advanced auto parts to have them load tested, one battery had a bad cell, got new battery and boat fires up now like a car!!!! check your batteries.

Morning!

I bought my boat last month a 1994 280 SunRunner with a 7.4 litre 454 V8. According to a MerCruiser bulletin says it needs a battery of 450 CCA or 550 MCA or 90 amp hour. I am not sure of the battery the last guy threw in there but it seems the engine turns over real slow before actually cranking. My battery has died on me before while trying to crank and if I hook up a portable battery jump the engine will turn fast and start right up. I know this is a carbed engine and requires a little more finesse than an EFI but it seems strange that it turns over so slow. My battery gauge shows good at 16 while running. I have NO problem with the alternator.

Can I put a bigger battery in there or will that push to many amps to the starter?

I would like to fix this problem today as it is going to be almost 90 here this weekend in SUNNY FLORIDA!!!!!

 

[CliffA]

I would check the actual voltage output of the alternator while running vs what the gauge reads. If it really is putting out 16VDC you will boil the battery dry.
Other than that, it was all well said above.
Enjoy the nice weekend!

+1 on this......your gauge should not read more than 14.5V while charging.....if you are getting more charging volts than 14.5V you should check your voltage regulator in the alternator......

cliff

 

[CV-23]

Yep....a bad cell can pull both batteries down. I just put two Group 31 batteries (208 min reserve) in my 270. They are really heavy! My old batteries were in the boat when we bought it in 2010 and were 2007 vintage (a 31 and a 27). Each one had a bad cell but the on-board smart charger was hiding it. Once we were off shore power for two weeks the boat would not start.....battery switch was Off also so no reason to die other than bad cells. The battery acid hydrometer told the whole story last fall after close inspection.