Starting or Deep Cycle

[Mstrlucky74]

Have a 1998 sea ray 215 express cruiser. For the electronics I have a chart plotter, fusion radio, a few led lights and going to install a 12v tv.
ive read so many conflicting opinions on what to have.
should I have two deep cycle batteries or one deep cycle and one starting? I currently have a Die Hard platinum deep cycle that I bought last year. The other battery is very old and needs replacing. It's a west marine dual purpose. Thanks

 

[paulswagelock]

If you plan to use the house load, that should be deep cycle.
The second battery should be your starting battery, and should not be deep cycle, but very high amp starting battery.

 

[Mittens]

I would personally have 2 deep cycles, they will start the motor just fine.

 

[skibum]

I just installed 2 Optima blue top deep cycle / starting batteries in May. So far, they have performed very well.

 

[paulswagelock]

I would personally have 2 deep cycles, they will start the motor just fine.

A true deep cycle is low amp, high reserve capacity and will not start a boat. You are talking about a dual purpose battery that is often called "deep cycle".
The term deep cycle has no technical basis, and can be used by a manufacturer at will.

 

[NotHerDecision]

You should have 2 batteries. A deep cycle house load setup and a standard starting battery. This will allow you to always have a starting battery while loading/draining the deep cycle down to its rated charge depth. The issue with this is that sometimes it takes buying new batteries, a new charger, and possibly some wiring so you get all of the answers like. It will be fine... mine is like this... just do this.... the real answer is you should have a house deep cycle and a starting bank and a charger that can properly charge both.


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[Mittens]

A true deep cycle is low amp, high reserve capacity and will not start a boat. You are talking about a dual purpose battery that is often called "deep cycle".
The term deep cycle has no technical basis, and can be used by a manufacturer at will.

yes, this is correct. The boat he is talking about and the loads are not in need of some giant true deep cycle set up. just your standard 2 battery boat set up use one, save the other kinda deal. but dont use starting as they kill faster and dont like to be discharged like that.

 

[Stee6043]

Perhaps ignore the label on the battery and simply look at cranking amps and reserve capacity. I installed three "deep cycle" batteries this Spring. Each has a CCA rating of over 700 and bookoo reserve capacity. More than enough to crank a big block in spite of being labeled a "deep cycle".

 

[Mittens]

contrary to popular belief. a big block is not hard to crank, the starters are geared very low, and they are not high compression motors. just FYI to the thread. 700CCA will do the job.

 

[Creekwood]

You should have two batteries and a battery switch to allow you to set it to 1, 2, Both, and Off. It was not clear that you have that set up. If you don't have a switch, the two batteries should be the same exactly (age, type, brand etc.).

Assuming you have a switch, I would have one dual purpose (start/deep cycle) that is your starting one. And then a true good deep cycle for your "house" one that you can use to draw on while at anchor. Unlike what others have said, there is a difference in that deep cycles are made with thicker lead plates that can take deeper discharge and be recharged. The trade-off is less cranking amps due to less surface area of the plates. Cranking batteries have thinner plates with more surface area and can discharge more amps. They don't like deep discharge/recharge though. If you run a cranking battery down, it does not come back to full charge and will "wear out" faster.

You should have a dual bank charger so that each one is separately charged. Don't set the switch on "Both" unless really necessary and definitely not while charging.

A deep cycle will crank a motor. It will just crank at noticeably lower speed. Its not ideal for a cranking battery.

 

[paulswagelock]

contrary to popular belief. a big block is not hard to crank, the starters are geared very low, and they are not high compression motors. just FYI to the thread. 700CCA will do the job.

Modern Merc engines with electronic ignition have a stout CCA requirement to satisfy the ignition, spin the engine fast enough to build oil pressure to release the fuel limit switch, and start the engine without a voltage drop. For instance my 8.1 has a minimum requirement of 820MCA and 175 RC.

 

[skibum]

For instance my 8.1 has a minimum requirement of 820MCA and 175 RC.

Battery technology is getting better every year. The DP Group 31 Blue Tops have 900 CCA with a 155 RC. They spin my 8.1 better than any of the various wet cell batteries that I have ever had.

The dual purpose BlueTop (light gray case) can be used for both starting and deep cycling -- it is a true deep cycle battery with extremely high cranking power. Uses include: trolling motors, marine applications with heavy electrical accessories, and RVs.

• 12-Volt, 900 Cold Cranking Amps, Size: 12 13/16" x 6 1/2" x 9 3/8" tall, Weight: 59.8 pounds, Dual SAE & 5/16" Stainless Steel Stud Posts
• Reserve capacity of 155 minutes for constant performance

 

[paulswagelock]

Those are good batteries for sure, but at 2-3x the price of an equivalent capacity wet cell, my $$ goes for the wet cell.

 

[skibum]

LOL. I agree. I got lucky this year. The only maintenance items on my list was a new seat for the head ($67) and new batteries. I caught a 25% off sale at Pep Boys, so I bit the bullet. I installed a new Promariner 1220P last year and wanted to put that AGM profile in it to the test. Compared to previous years, I started off the season with a fat wallet, so I also splurged on BoatUS unlimited towing... I figure that if nothing was broken before the season started, there's something waiting to break mid-season.

Boating rule #2 - You can NEVER make everything on a boat work at the same time. If you think everything is working, there is something broken that you just haven't found yet.

 

[Mstrlucky74]

You should have two batteries and a battery switch to allow you to set it to 1, 2, Both, and Off. It was not clear that you have that set up. If you don't have a switch, the two batteries should be the same exactly (age, type, brand etc.).

Assuming you have a switch, I would have one dual purpose (start/deep cycle) that is your starting one. And then a true good deep cycle for your "house" one that you can use to draw on while at anchor. Unlike what others have said, there is a difference in that deep cycles are made with thicker lead plates that can take deeper discharge and be recharged. The trade-off is less cranking amps due to less surface area of the plates. Cranking batteries have thinner plates with more surface area and can discharge more amps. They don't like deep discharge/recharge though. If you run a cranking battery down, it does not come back to full charge and will "wear out" faster.

You should have a dual bank charger so that each one is separately charged. Don't set the switch on "Both" unless really necessary and definitely not while charging.

A deep cycle will crank a motor. It will just crank at noticeably lower speed. Its not ideal for a cranking battery.

thanks. I do have a battery switch 1,2 and both. That's leads me to another question as there are differing opinion. When cruising should the switch be on 1,2 or both?

 

[Mstrlucky74]

The good battery that doesn't need replacing is a die hard platinum 850cca

 

[Robf]

Always charge on one or two, never on both. Both should only be used as a boost to start. If charging on both, a bad battery will discharge a good battery.
Rob

thanks. I do have a battery switch 1,2 and both. That's leads me to another question as there are differing opinion. When cruising should the switch be on 1,2 or both?