Dual Purpose or Deep Cycle???

[USA_boater]

CURRENT SETUP

Four Winns Horizon with a Perko dual battery switch. Right now I've already bought one Duracell 24 dual purpose from Sam's Club and am borrowing my Optima yellow top from another vehicle until I buy a second battery. The boat has a 15yr old Clarion XM receiver and stereo w/ 4 speakers..no sub woofer but does have good bass and sound so I assume it is at least 100w system (boat is new to me).

WHICH OPTION WOULD YOU CHOOSE & WHY

1.) Buy another identical dual purpose and run bank 1 all day and only switch to bank 2 if bank 1 is run down? There is only 15 dollars difference between the Duracell dual purpose and marine starting battery so spending 15 bucks seems worth it if it saves me from having to open the cover and make the switch. This is the option I'm leaning towards.

2.) Run a deep cycle on bank 2 and always switch over to bank 2 when wanting to run stereo while anchored, etc? (this is what I currently do w/ the optima but switching sort of a hassle)? This is the option I'd be leaning towards if the boat had subs or was a trolling/bass boat. Duracell deep cycle is 80bux.

3.) Save some money and get a 59 dollar Marine starting battery from Sam's and run it on bank 1 and the existing dual purpose on bank 2 and continue to switch between them as necessary?

Let me know or if not one of these options what you'd do in my situation...I have some high-end batteries in my Jeeps but I just can't justify spending a lot on boat batteries unless it was a cruiser or houseboat. Thanks!

EDIT: forgot to ask about the "ALL" selection on the dual battery switch...what happens if you leave the switch on "ALL"? will it use both batteries power equally? It might be nice to have them both receiving a charge from the alternator while the engine is running, but there again I'd have to switch back to bank 2 for long periods of radio...is there any risk/advantage to the "ALL" option that influences which of the 3 choices I've laid out is best?

 

[Blind Date]

I run 2 Sears DP batteries in my 250 Sundancer. One time I ran my refrigerator while I was trailering to Lake Superior for over 14 hours. It started the motor effortlessly once i reached the Apostle Islands and put in. Only way I'll ever go and I think most trailerable cruisers are set-up this way when new.

 

[USA_boater]

Hey thanks...makes sense considering the dual purpose are a sort of deep cycle themselves...I don't "plan" to run the batteries way down regularly like trolling would do so perhaps the dual purpose is fine for what I'll be doing. The Sam's club DP is 65ah and the DC is 75ah so not a huge diff in specs...I did read in one of the reviews that the sump pump companies recommend true deep cycle...this boat has a sump pump that turns on automatically...But since the dual purpose is also a milder deep cycle I guess it would work fine none the less.

 

[USA_boater]

EDIT: I just noticed something...your battery is a 27group w/ 180min RC...that is a heftier battery than the group 24's I was using...even the true deep cycle duracell 24 series doesn't have that good of spec to the battery you use. Perhaps that means the deep cycle is best for me as it still should have enough CCA/MCA

 

[H20Rat]

Do you need dual batteries? Yes, they are nice to have, but from what you said, your use case doesn't really need it. Go with a single large (group 27 or even 31) deep cycle. I've run nothing but deep cycles as starting batteries in both my RV and boats for awhile, they have no problems starting it at 'normal' temps. Yeah, if I wanted to start my boat at -20, probably isn't going to do it, but that isn't much of a concern!

 

[USA_boater]

Well you are probably right...but the previous owner had already added the second battery switch...I hate to waste it...perhaps I'll just get a deep cycle and run it on bank 1 all the time and keep bank to (cheaper, smaller dual purpose) as a backup...As long as I keep it charged that should work.

 

[sillyhilley]

I would two batteries on! Even if you don’t need it. It all about having it and not needing it opposed to needing it and not having it

 

[dingbat]

Batteries are no place to cut corners, especially on a boat where loosing power could be the difference between life and death.

I run two grp. 27 deep cycle batteries with an ACR. Turn the switch on at the dock, turn it off when I get back. About as fool proof as it gets

 

[MTboatguy]

On my Starcraft I am running a Heavy Duty deep cycle group 27 and have never even run close to depleting it. I use it for starting, trolling and my fish finder, I picked it up at O'Reilly and it has been a good battery, when it is time for a new one, I will probably go to a two battery set up but one has worked out so far. I had this in my 14 foot utility before I bought the Starcraft, so it is a couple of years old. I trailer, so I put on a battery maintainer between every trip,

 

[bruceb58]

Almost every marine battery that is labeled deep cycle is not a true deep cycle and is actually a hybrid dual purpose battery. If you want a second battery that can start your boat, you usually want to have the second battery be a dual purpose battery.

A TRUE deep cycle battery may have trouble starting your engine if you have electronic fuel injection. Most engine manuals will say what the minimum CCA or MCA is required from your battery. You will notice that most true deep cycle batteries will not even have a CCA spec.

In my Wellcraft, I have 2 Odyssey AGMs. They are not true deep cycle batteries either but are better at surviving multiple deep cycles than flooded lead acid dual purpose batteries.

 

[USA_boater]

Thanks guys, I think I've decided to get a group 24 deep cycle as the primary battery and use the existing dual purpose as the backup...I just can't justify the cost, weight, etc. to go with a larger, more expensive battery unless I was only running one...I am 99% sure the gp24 deep cycle will probably never run down on one of my outings from listening to the radio...if it does, I'll have the backup anyway...the LATER, if my experiment fails, maybe I'll upgrade to a gp24 dual combined with a gp27 deep cycle...I agree that many of the "marine" batteries are dual purpose, although Sams's sells specifically a dual and a deep and I am pretty sure even the deep will start a carbed 4.3 V6...if not, I'll use the other battery for starting.

 

[H20Rat]

Batteries are no place to cut corners, especially on a boat where loosing power could be the difference between life and death.

All depends on your use case... Losing power on one of the lakes I boat on just means you have to use the pull starter on the 15hp kicker, or drift to shore, which will take about 15 minutes at most.

2 batteries adds more complication and additional points to fail, and also potentially puts more stress on your alternator, which could cause that to fail sooner. Having two batteries might very well be the cause of your boat being dead in the water. I'm a firm believer in matching the solution to the problem.

 

[USA_boater]

Well I'm not going to leave the dual switch on "ALL" so the alternator should not feel it much LOL...I am going to try and run as if I have one battery and then only use #2 for emergency.

 

[bruceb58]

All depends on your use case... Losing power on one of the lakes I boat on just means you have to use the pull starter on the 15hp kicker, or drift to shore, which will take about 15 minutes at most.

2 batteries adds more complication and additional points to fail, and also potentially puts more stress on your alternator, which could cause that to fail sooner. Having two batteries might very well be the cause of your boat being dead in the water. I'm a firm believer in matching the solution to the problem.

I will never own a boat that has just one battery. It's the first modification I do. Hard to imagine thinking adding a second battery is really all that complicated. The switch has an extra contact and you add a couple more cables. How is that complicated?

 

[MTboatguy]

I have in the past used a small solar battery maintainer while out in the boat, it is a suitcase model that I picked up at HF and it seems to keep things up to snuff when I am running a single battery, at least I have never had one get so low that it would not start the engine on the boat. it is not big only 13 watts but it seem to do the job. Of course I am not running a lot of electrical draw while we are out.

 

[bruceb58]

it is not big only 13 watts but it seem to do the job. Of course I am not running a lot of electrical draw while we are out.

It's only going to put out 0.75A at its max. Probably good for keeping your phone charged!

 

[MTboatguy]

It's only going to put out 0.75A at its max. Probably good for keeping your phone charged!

Like I said we don't use a lot on the boat, most of the time just the Humminbird, and maybe to charge batteries for our handheld marine radios/weather radios. Like I said, I will probably upgrade and put a second battery in when it is time to replace this one, just need to do some wiring as I don't want them both in the rear of the boat with 2 tanks of fuel.

 

[USA_boater]

I also have a name brand solar maintainer and I found it works well for hooking up when the boat is on the trailer with the cover off...so for example, if I took a weekend trip, I could use it to top off batteries in between lake outings.