Battery cranking amps...Is more better?

[kaliona]

Shopping for a new starting battery for my boat. I plan on just getting an automotive battery strictly for starting the boat. It's a 165hp I6 Mercruiser. Should I choose a battery with the highest CCA/MCA rating? I figure more is better....or will too much damage the motor in any way? For $10 to $20 more, I can get a 700 or 800 CCA battery over a 600 CCA battery. Any thoughts or opinions on this?

 

[JB]

Re: Battery cranking amps...Is more better?

Marine batteries are built to survive the shock of marine use. I would avoid car batteries.

 

[smokeonthewater]

Re: Battery cranking amps...Is more better?

more is ALWAYS better and won't hurt a thing.... also I have used car batteries for decades in boats without any trouble at all.... I''m 100% certain that they get beat MUCH harder in my jeep than anything on water short of offshore racing

 

[Silvertip]

Re: Battery cranking amps...Is more better?

A bigger battery does not spin the engine faster. It just allows the starter to spin the engine longer. Damaging the starter is possible if you have a hard starting motor and continue to crank it for long periods of time with no pauses to allow it to cool off. Size of the battery has nothing to do with that. Batteries are like buckets of electricity. A bigger battery has more capacity -- not more voltage.

 

[smokeonthewater]

Re: Battery cranking amps...Is more better?

while cranking for too long does indeed kill starters, more are killed by cranking without sufficient power available

Also higher amperage CAN spin the engine faster if the lower amperage was not enough to maintain voltage while cranking

A battery with x cca is rated to maintain x volts at x temp under x amps load for x seconds .... soooo if say 600 cca battery maintains 10.5 volts with 600 amp load (just wild guess numbers) It is not unreasonable to suppose that a higher rated battery might maintain say 12 volts at the same load.

example, my powerstroke will start on one battery in the summer but cranks faster and starts quicker with two. same no load voltage but higher cranking voltage. No way would it start with one in the winter tho. Your 250 ci straight six, if all is in good order, would be able to start just fine from a lawn mower battery and many years ago I drove a suburban (tbi 350) over a year with a lawn mower battery under the hood but, as I said before, more is better.

the biggest reason to get the bigger battery is for the reserve capacity. IE how will it crank if partially depleted..... OR how long will it fire the spark plugs if the alternator fails.

I hope this makes things clearer....

 

[smokeonthewater]

Re: Battery cranking amps...Is more better?

I will add... If you ARE gonna use an automotive battery in a boat, use a top post battery with a good brass? adapter to the ring terminal cables.... don't cut off the ends and use the crappy clamps that so many people ruin their battery cables with.... If you already have those cable ends, get new cables or get ring terminals crimped on.... Wing nuts are so much easier to fool with when you are bobbing about with a batt problem.

also use grease on the posts. corrosion is no fun

 

[fishrdan]

Re: Battery cranking amps...Is more better?

I'm running the same battery my truck uses, on my 140 Mercruiser. It was cheaper and had a longer warranty than a marine start battery, and if my truck battery dies while towing I can swap the boat battery over easily, or the other way around. (I had the truck battery die once while towing, big PITA trying to get the boat battery to work.)

I used the same brass terminal adapters SOTW was talking about. They were tough to find (Ace Hardware), but worth it.

 

[Bondo]

Re: Battery cranking amps...Is more better?

Batteries are like buckets of electricity. A bigger battery has more capacity -- not more voltage.

Ayuh,... You could have a Bazillion CCA/MCA rating, 'n the load will only draw what it wants....

as explained above,...
Whatever the load is won't work any faster,... Just Longer....

 

[NetDoc]

Re: Battery cranking amps...Is more better?

I will add... If you ARE gonna use an automotive battery in a boat, use a top post battery with a good brass? adapter to the ring terminal cables.... don't cut off the ends and use the crappy clamps that so many people ruin their battery cables with.... If you already have those cable ends, get new cables or get ring terminals crimped on.... Wing nuts aret so much easier to fool with when you are bobbing about with a batt problem.

also use grease on the posts. corrosion is no fun

Bravo! Bravo! Those replacement ends are horrible and will cause all sorts of issues including premature battery, alternator and starter failure.

As for automotive/marine... I went with the marine one.

 

[kaliona]

Re: Battery cranking amps...Is more better?

Thanks for all the input guys. I'm not worried about the battery taking a beating since I mainly fish lakes and calm waters of the delta. Engine is in good shape so I'm not worried about "overcranking" it. And the longer warranty of an auto battery over a boat battery is just another plus for me.

 

[fishrdan]

Re: Battery cranking amps...Is more better?

double post

 

[smokeonthewater]

Re: Battery cranking amps...Is more better?

don't get me wrong... I PREFER the marine batts for the studs on top and the pretty colored plastic case but if I need a batt and happen to have an auto batt that fits the need I have no prob using it.... Now try to get me on the water with only one batt and you'll see my stubborn side

 

[fucawi]

Re: Battery cranking amps...Is more better?

Unless I missed it ..the CCA on a car battery are at -18 deg C and on a marine battery at 0 deg c so beware.... a marine battery of the same CCA is worse than the car one. The only figure that they cannot fiddle is the Reserve Capacity ..how long it will supply 25 A in minutes......I always use car batteries for my boats ...no problems ..why should there be as long as its bolted down ....it carnt tell if its a bump in the road or a wave .

 

[Texasmark]

Re: Battery cranking amps...Is more better?

On how much spin a battery can provide has to do with circuit resistance.

If all things in the external circuit are equal, the battery with the lowest internal resistance will spin the starter faster as the lower that resistance, the lower the battery drop is of the available voltage leaving more available to go across the starter.

Considering the starter a fixed resistance, then more voltage on an equal resistance means more current and that means it spins faster. Butttt so what. If your equipment is in good working order, you could start a GMC 350 engine with a lawn mower battery as "smokeonthewater" says he did. It's all relative.

I use OTR truck batteries in my diesel tractors because they have 3/8" stud terminals and WW or Autozone in everything else. I have not had a battery short out because sulfide collecting between the plates due to shock, like the shock of hitting a big wave repeatedly. Seems to work for me.

Does this make sense? Probably not but it's free for the time you spend to read it.

HTH,

Mark

 

[fucawi]

Re: Battery cranking amps...Is more better?

you wont get the vibration problems of old with modern batteries as there is now no sediment space at the bottom to fill up with conductive shonet and short out the plates....the plates go to the bottom and are set in resin....the space is now at the top hence less need to top up ...

pronounced sh one t where one = i