96f350psd

Can some one tell me the difference between a deep cycle battery and a marine battery. Which is a better battery?

NightHawk

The term marine as applied to batteries indicates the ratings are measured at 32 degrees F as opposed to automotive batteries rated at 0 degrees F. There are 3 basic types, Marine starting, marine deep cycle and marine dual purpose. Deep cycle batteries are optimized for long slow current draw and deep extended period dicharges for running accessories. They can be used to start the engine but will not be as effective in some cases.

The starting batteries are optimized for large brief current supplies for engine starting. However they will sulphate easily if left dicharged and become less effective.

The dual purpose batteries are a compromise between the two, mainly for single battery installations.

96f350psd

This might be a dumb question but which one is really better for a boating aplication?

tcelano

Not a dumb question at all. Nighthawk is exactly right, so the answer to your question must be based on how you intend to use the battery. Many boats employ separate banks of batteries, some for starting duties and some for house loads. If you intend to overnight or raft up all day long with accessories running, you'd be best served by having an isolated bank of house batteries of the deep cycle type to draw from. Meanwhile, your engine starting batteries would remain fresh. This is accomplshed through the use of a battery isolator which is just a large diode that allows your alternator to charge all the batteries, but won't allow your starting battery to discharge anywhere except to you starter. Since batteries of different types don't like being mixed in a bank too well, another popular solution, amongst large yachts anyway, is to use the alternator from one motor to charge exclusively the house batteries, and the other motor to charge the starting batteries. This ensures that they charge at the proper rates and achieve the proper voltages to burn off the sulfate, and keeps them fully separated to avoid any electrical gremlins.

I have a lot of experience operating big lead acid batteries aboard Nuclear Submarines. There we have tons of incredibly anal rules and procedures for conducting different types of charges, test discharges, and maintenance well above and beyond what you have to do when your life doesn't depend on them. The big picture though is to make sure that you never fully discharge one, especially when it is wired to others, in which case cell reversal can happen. Then it's done. Make sure you have enough alternator capacity to really charge them as well. Without giving them that equalizing charge they need to burn the sulfate off the plates, you will rapidly lose effective plate area and maximum current ability, and shorten the cell life.

Stormrider

I just installed a (1)started battery, and a (2)deep cycle battery.
When engine is started, put battery switch to (1) and run on (1).
When I stop and raft up, switch to (2). On way home, switch to both, start engine, and run on both.

Macklin

Good question. I just bought new batteries after doing much research. I looked at sealed batteries, but could not justify the price knowing I may be moving up in a year or two. My boat came with dual purpose deep cycles - Interstate SRM-27's. They only have 750 MCA. I found out that the computers on my HO's require at least 750 MCA. I decided to stay with the dual purpose deep cycles because I do spend a lot of time on the hook running the stereo and sometimes the fridge. Interstate has come out with a new battery, the SRM-27B, that has 845 MCA. Retails at $89. My marina gave me a deal on them for $72 each.

Outdrive1

I've had nothing but bad luck with those Interstates. I wouldn't buy anything less than an Optima or another comparable brand (Lifeline, etc.). The yellow tops are dual purpose and have well over 1000 cranking amps. They are a little more expensive but I've never been stuck with a dead one. I've also run my stereo until the amps shut off from low voltage and they will still crank the motor. I run four yellow tops, two on each side of the Perko switch. The wimpy 60 amp alternator Merc puts in the boat can't get close to charging them. I put a charger on them when I put the boat away and charge them myself. I'll charge them for a few days with an automatic charger and unplug it until a day or so before I'm ready to go out again. I know people use Interstates and have good luck with them, but it's well over 115 degrees in Az. in the summer, regular batteries in your car or boat die out here all the time in the summer. You'll go out to your car in the afternoon out the blue and have a dead battery with no warning. At least with Optima's you generally get a two year free replacement (maybe 1 with the blue and yellow tops). Out here it's worth the money to buy them. Not only that they look so damn cool..........

bck

I was told that deep cycle batteries charge at a slower rate and that you most likeky will not charge them fully while running the boat. Anyone know of this?

jboater

My experience with deep cycle batteries has been great so long as you can put small amps back into them, they discharge slow to they need to be recharged slow, charge them fast with anything more than 8 or 10 maps and you will be boiling the water out of them.

TELLefant

Best you can do is: mount a Pulser and your problem will be gone. I do with batteries almost every single day and since we use this pulstechnology we saved some good money... ;-) Check that out: http://www.pulsetech.com
Cheers!