The Boating Forum - Do I really need a cranking battery?

Here's the situation - I'm about to replace two Exides in my boat, all of which are around 3 years old (Yamaha F150). Currently I have a cranker and a deep cycle but I've noticed the Sears Diehard platinum battery 34M with its 880 CCA. It's officially a deep cycle but that's far more CCA than my current cranking battery carries. I'm not concerned with price, just the practicality of relying on deep cycle to always crank. Does that make sense? Oh and 3 year replacement....not bad. Many thanks.

Here's the link - mash here (http://www.sears.com/shc/s/p_10153_12605_02850134000P?prdNo=2&blockNo=2&blockType=)

Cranking batteries are not suitable for deep discharges. A deep cycle battery can be discharged and recharged without damage, but doesn't have the high cranking amperage a starting battery has. In practice, you'll never draw 880 amps without melting something. One a boat, I'd rather have deep cycle capacity than CCA. Besides, with 2 batteries you can combine them if necessary.

One a boat, I'd rather have deep cycle capacity than CCA.

But with such a battery I'd have both, yes?

I guess what I don't understand is the assertion that a deep cycle won't have as much amperage as a cranking, when the one I'm looking at has 880 and the cranking I currently have is like 650. Why would I not really receive 880? Thanks. Or am I mistaken in thinking this is a deep cycle battery with exceptional CCA?

Yes you'd get the same benefit from what you're looking at.

As for the cranking amps, that's AVAILABLE amps, not what you'd actually use. If you starter only draws 200 amps, that's all you'd get. BTW, it takes a HUGE wire to conduct 880 amps.

Yes you'd get the same benefit from what you're looking at.

As for the cranking amps, that's AVAILABLE amps, not what you'd actually use. If you starter only draws 200 amps, that's all you'd get. BTW, it takes a HUGE wire to conduct 880 amps.

Okay I'm following. It's worth something to know I've got another cranking battery available whenever needed. Plus if I ever pull them out for something, I don't have to worry about what all is attached to which battery. Thanks.

Now just to make sure they'll fit....

Hooking batteries in PARALLEL gives the same voltage, but DOUBLE the cranking amperage. As in, when you switch your battery switches to both. for this reason, CCa from a single battery is a non-issue.

When looking at fit, make sure the terminals fit also, and are positioned properly for your particular boat.

I have 4 Optima Blue Top deep cycle batteries on my boat, no cranking battery.

THey are making somewhat of a hybrid now, it has enough for the starting function and more staying power - I just put 2 Marine Maxx in mine from wal-mart. Before you laugh the one I replaced is dated 2006 and its not dead just is a straight deep cycle and doesn't have the ummmph for my current set up - $70

Hooking batteries in PARALLEL gives the same voltage, but DOUBLE the cranking amperage. As in, when you switch your battery switches to both. for this reason, CCa from a single battery is a non-issue.

I considered that, but I'm pondering a scenario in which the battery just dies/malfunctions altogether....not unrealistic. I wouldn't then want my other battery to be a deep cycle. I'd then just switch over to the other battery and we're off. Basically if I'm 20 miles offshore, the battery quits, I don't want to tell my fishing partner "The good news is that Sears will have to replace this battery" as we wait for the towboat.

When looking at fit, make sure the terminals fit also, and are positioned properly for your particular boat.

Definitely.

A Yamaha 150 doesn't take a huge battery to crank it. A good lawn mower battery will crank that thing. for this reason I wouldn't be overly concerned.

I only use deep cycles.
You will be fine with them and have more reserve current than a cranking batt for more important things, like pumping out water if something goes wrong on the water.

You are doing the right thing dumping the exides. They are the worst batteries, both auto and marine.

A Yamaha 150 doesn't take a huge battery to crank it. A good lawn mower battery will crank that thing. for this reason I wouldn't be overly concerned.

That being the case, I'm starting to think my Exide deep cycle batts are junk.

You could have a bad connection(s), that will cause voltage drop to the starter. A bad connection, even a ground, will manifest itself by becoming hot to the touch. Of course, a bad battery will also give these problems. All connections, including the ground from the engine to the batteries, must be squeeky clean. Corrosion at the battery is cleaned/neutralized with baking soda.

A battery being labeled as a cranking or deep cycle can be confusing.

The best way to land on the appropriate battery is to first focus on finding a battery that meets the minimum specified MCA and CCA for your motor (should state this in the owner's manual). Once you have found some batteries that meet this minimum requirement, then go with the battery with the highest RC (reserve capactiy). The RC # is the minutes your engine will run with an inoperative alternator.

Generally, a starting battery will have a higher MCA/CCA and lower RC, while a deep cycle battery will have a lower MCA/CCA and a higher RC.

I have two deep cycle Optima batteries in a 23' boat with 250 ETEC.

Go with the Die Hards. I have two of them, they've been great. They are made by Odyssey. Yes they're deep cycle and starting.

A battery being labeled as a cranking or deep cycle can be confusing.

The best way to land on the appropriate battery is to first focus on finding a battery that meets the minimum specified MCA and CCA for your motor (should state this in the owner's manual). Once you have found some batteries that meet this minimum requirement, then go with the battery with the highest RC (reserve capactiy). The RC # is the minutes your engine will run with an inoperative alternator.

Generally, a starting battery will have a higher MCA/CCA and lower RC, while a deep cycle battery will have a lower MCA/CCA and a higher RC.

I have two deep cycle Optima batteries in a 23' boat with 250 ETEC.

Well said.

You do not need a cranking battery unless you are running a big block V-8 inboard. Get yourself two good deep cycle batteries.

And 850CCA deep cycle battery is just as good at cranking as an 850CCA cranking battery. Probably better in a slightly discharged situation.

There are some excellent models now which do both CCA and deep cycle in one.

I only use deep cycles.
You will be fine with them and have more reserve current than a cranking batt for more important things, like pumping out water if something goes wrong on the water.

You are doing the right thing dumping the exides. They are the worst batteries, both auto and marine.
I know, I have 2 Exide batteries. One lasted only 5 years and the other is going on 7 years. (Aug) :tht_rulez: ps their not deep cycle either and I run everything off of them. One battery out and the other one back.:thumbsup:

I have been using Optima Blue top Deep cycle batteries for over 15 years. I have never used a cranking battery. I have always used 2 deep cycle batteries. I have never had any issues with cranking my motor.

Put them in today. Each time I cranked on either battery the engine was turned over with nothing but a quick "tszzt". Much quicker than my old cranking battery and only 14 min less on the reserve capacity than my deep cycle (120 vs 134). I think this was the right call.

Yep!

I know, I have 2 Exide batteries. One lasted only 5 years and the other is going on 7 years. (Aug) :tht_rulez: ps their not deep cycle either and I run everything off of them. One battery out and the other one back.:thumbsup:

That can happen. For every scenario on the board there is always 1 or 2 "never had a problem" out there.
They may even have improved them but I have seen way too many failures come back with these batts to ever consider buying one for myself or my family, not to mention installing a set in MY boat and heading offshore. Exides, ANY battery except an Exide. Sorry.

A battery being labeled as a cranking or deep cycle can be confusing.

The best way to land on the appropriate battery is to first focus on finding a battery that meets the minimum specified MCA and CCA for your motor (should state this in the owner's manual). Once you have found some batteries that meet this minimum requirement, then go with the battery with the highest RC (reserve capactiy). The RC # is the minutes your engine will run with an inoperative alternator.

Generally, a starting battery will have a higher MCA/CCA and lower RC, while a deep cycle battery will have a lower MCA/CCA and a higher RC.

I have two deep cycle Optima batteries in a 23' boat with 250 ETEC.

You generally have a good description here, but reserve capacity has nothing to do with the number of minutes an engine can run with a dead alternator. it is the time it takes for a fully charged battery to discharge to 10.5 volts (i believe) under a 20 or 25 amp load (think its 25). Especially important if running electronics off house battery without a charging source.

Low voltage is more important now than a decade ago. Older electronics could tolerate low voltages and still work..new digital stuff, if it doesn't see 10-10.5 volts it just quits working. This often occurs when cranking loads drop the available voltage..even though it "cranks" there's not enough voltage to make the dam computer work.

manufacturers don't like deep cycles on their motors. deep cycles need to be drained completely then recharged if not it gets the memory. Manufacture will tell you no deep cycles and no gel cells.

And if there wasn't any proof they wouldn't publish it in the manuals.

manufacturers don't like deep cycles on their motors. deep cycles need to be drained completely then recharged if not it gets the memory. Manufacture will tell you no deep cycles and no gel cells.

Lead acid batteries do not develop "memory". thats a crock.

Tell that to mercury and yamaha and all their engineers.

markie1, can you read and comprehend? It is those rechargeable NiCd's that develop a memory.

Listen I've been to mercury school and was told not to use them cause of that reseason so I will take their word before yours

Listen I've been to mercury school and was told not to use them cause of that reseason so I will take their word before yours

Either your instructor was an idiot or you have comprehension issues

From Trojan website:

Does my deep cycle battery develop a memory?
Lead acid batteries do not develop any type of memory. This means that you do not have to deep discharge or completely discharge a battery before recharging it. For optimum life and performance, we generally recommend a discharge of 20 to 50% of the battery's rated capacity even though the battery is capable of being cycled to 80%

From optima site

Does the OPTIMA Deep Cycle battery have a "memory"?
No. The performance of both deep cycle and starter batteries will be reduced over time, but OPTIMA Deep Cycle batteries do not suffer from "memory effect" such as NiCad batteries do.

From motorsport land site:
No! Lead-acid batteries do not develop a memory. What does this mean to you? Lead-acid batteries have the ability to cycle to various amounts of depth of discharge (DOD) anytime during their service life without a memory developing inside the battery.

From JGDarden site:

14.12. MYTH: Lead-acid batteries have memories.
False! Lead-acid batteries do not have the "memory effect" mistakenly identified with first generation Ni-Cad batteries; however, continuous undercharging will lower the capacity of the battery over time due to the accumulation of permanent lead-sulfate or "sulfation". Deep discharges below twenty percent State-of-Charge (approximately 12.0 volts) can damage batteries and will shorten their service lives.

Well, I agree with CB. There is no "memory" problem with deep cycles. Gotta buddy who owned a battery store...he should know.

The only time you deep discharge/recharge a conventional wet cell is when they start to sulfate.

BTW, you better inform the golf cart industry THEY are doing it wrong...........

That can happen. For every scenario on the board there is always 1 or 2 "never had a problem" out there.
They may even have improved them but I have seen way too many failures come back with these batts to ever consider buying one for myself or my family, not to mention installing a set in MY boat and heading offshore. Exides, ANY battery except an Exide. Sorry.

Oh, I forgot to mention that the one battery that has been totally reliable all this time is actually an Interstate cranking battery. So I can't even extend Exide credit for that! Two Exide deep cycles have been total POS's and would have been unreliable as a back up, were my Interstate to fail.

Lead acid batteries do not develop a memory.

There are really only two differences between a cranking battery and a deep cycle.

1. Plate thickness. Deep cycle batteries have thicker plates than cranking batteries.

2. How they are rated. Deep cycle batteries are rated in MCA (Marine Cranking Amps) while cranking batteries are rated in CCA (Cold Cranking Amps). The difference between the two is 32 degrees(CCA=0 deg, MCA is 32 deg).

Here is the best thing I can say about battery life. Battery life expectancy is rated on "cycles" which without getting too technical is how many times you can fully discharge and charge your battery. Most 12v batteries we buy are rated anywhere from 200-500 cycles. Obviously the 500 cycle deep discharge battery costs more than a 200 cycle cranking.

Last thing on battery life. Batteries will self discharge if left sitting. It is bad to let a lead acid battery discharge completely. Keep your batteries fully charged and they should last.