marine vs car battery?

R

ronn

Well-known member
another question to those that know far more then me.........


while walking around walmart this morning, I noticed the higher prices of car batteries, but the marine batteries were cheaper, giving out more cranking amps and when I say cheaper, by a good 50 bucks.


other then being in a very cold climate, why wouldnt one choose a marine batt over a car batt, for far less $ and better cranking amps?
 
Back when I owned a sail boat, the marine batteries were always more expensive, and were characterized as "deep discharge" batteries. The idea was that they could supply the electrical needs on the boat (lights, radio, navigation, etc.) when the engine wasn't running and when shore power wasn't connected.

They achieved this deep discharge capability be having more room between the bottom of the plates and the bottom of the case. As lead-acid batteries discharge, some material from the plates flakes off, and will eventually cause shorting between the plates, and a filed battery. THis slight increase in the case size didn't account for all of the cost difference; it was more a supply and demand price driver.
 
Marine vs car battery?

Are you sure you're comparing like for like? High CCA automotive start batteries have different construction and greater plate surface area to achieve the high current yet brief demand periods. A genuine "marine" or deep cycle battery with the same CCA rating used as a starting battery would necessarily be very large, it would work electrically speaking, though it likely wouldn't physically fit your application.

Some of the sealed AGM batteries available today are kind of hybrid, in that they can handle repeated deep discharges and are sold for either application. This won't work going the other way, a typical automotive start battery as you know cannot survive long in a deep cycle application, I've read they are often ruined in as few as a half dozen deep discharges.
 
ok the marine battery gave out 850 cranking amps- 89.


the car battery 650 cranking amps 139.


that is my point and if its supply and demand- why am I not buying deep cycle marine batteries instead? both were the best walmart offered.
 
I used a "Deep Cycle" battery in my Model A without any problems. It lasted the same as a normal battery - about 8 years from memory. Deep cycle batteries are designed to withstand longer periods of non-use, as in a boat, caravan etc and that is similar to the frequency many people use their Model As. Nowadays I understand some modern batteries are hybrids and include features from both types.
 
Marine vs car battery?

If you've enough CCA for the application, it should work well. There are some differences in the way they are measured, CA are measured at 32° F. and CCA measured at 0° F.

And generator equipped charging systems are different than alternators, in that the entire electrical load is carried by the battery alone whenever the cutout sees no generator charging is taking place at idle speeds. This is where reserve minutes are important. There are important considerations other than CCA alone when selecting a battery, not everybody lives in the arctic zone, high CCA output comes at a cost both in terms of dollars and service life.

Had to pay $140 a couple weeks ago for a new 590 CCA deka for the Ranger from NAPA, and that was after whining for the jobber discount.
 
I will. most of my batteries come in for the winter anyway. just was wondering
what I was missing, other then a full deck!
 
"Marine" can mean a legitimate deep cycle design. This won't do as well for a starting battery.

It can also mean a hybrid that is for small sailboats, outboards, etc, that are expected to start engines and run lights and accessories when the engine is off for brief periods.

And then it might have "flag" terminals or other non automotive style.

If the terminals work, the Cold Crank rating meets your needs, and the case fits your battery box, I say save the $$.

Maybe check the date of manufacture too.
 
Starting batteries are designed to provide a large amount of current for a short time. As such they should not be discharged to more than 80% of their capacity. So a 100 amp-hour starting battery will only provide 20 amp-hours.

Deep cycle batteries are designed to provide a small amount of current for a long time. As such they will provide 50% of their capacity. So a 100 amp-hour deep cycle battery will provide 50 amp-hours.

Deep cycle batteries can start engines if the capacity of the deep cycle battery is large enough to proved the cranking amps. We had two huge deep cycle batteries that were wired in parallel on our sail boat. We also had a large starting battery to start the Diesel engine. We only used the starting battery when the house batteries were too discharged. Most of the time we used the house batteries and they cranked the engine faster than the starting battery. The house batteries weighed about 200 pounds each.

Marine batteries can be deep cycle or starting batteries or a hybrid where they can provide starting amps but discharge deeper than the normal starting battery. A compromise.

A good running Model A engine with good electrical connections and large cables can be started with a deep cycle battery. The deep cycle battery will run the lights and ignition longer than a standard starting battery without the generator putting out current.
 
nk, thank you for the explanation- what I was looking for. next battery I will try a marine battery. not necessarily for a model A.........just one of the cars.
 
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