Installing 2 Batteries on my 1985 Overnighter.......

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newtoboating28

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I just purchased a 1985 overnighter with single 200hp Mariner Engine. It currently has just one starter battery. I want to add a second deep cycle battery to connect a stereo and my Garmin Gps when the boat is not running. I know I need a (1, 2, both and off switch) connector for connecting both battries, as well as extra cables. My question is can someone please tell me the correct way to connect everything together without messing up my whole battery and electrical system. I do know that when operating the switch they say never change the switch setting while engine is running. I am just kinda confused on the conection configuration of all the cables. I am sure it's a very common hookup. I am a novice , and this is my first boat. Any step by step help would be greatly appreciated. :?
 
I'd stick with all starting batteries, Grady white ships their boats with all starting batteries. If the batteries will be on the same selector switch they will likely be in parallel, and should be the same type, not different. Wired in parallel is the most common way for boaters putting two batteries off one switch. For our boats and electrical systems you do not want them in series. You want to have a big starting battery, the largest you can fit in the boat with the most CCA's. Your electronics and such use a small amount of power compared to the engine itself.
 
Here is what you want to use.

http://bluesea.com/products/7650

That motor does not charge except when running above 2500 RPM so you'll live or die by your battery if you do a lot of slow speed operation.

I ran a pair of Delco grp 27 deep cycle batteries on my Overnighter and never had a problem.
 
Hey guys thanks for the info. So what your saying is it's better not to use a deep cycle battery for my stereo and my GPS? I just purchased a new Starter battery for my boat a couple days ago. The old one was dead and 3 yrs old. This new one was on sale at West marine for $50. It has Marine Cranking Amps at 650 , and a reserve capacity of 90 min. So if I bought a second one of these to hook my electronics up too, will that be ok? assuming I add the 1,2,both,off switch and run in parallel configuration like you said?
 
Yes, that should work perfectly. I have 2 550CCA starter batteries wired in parallel that starts one of my engines and runs all my electronics, plenty of power to run my radar, gps, fishfinder and cd player and 2 VHF radios all at same time. I am going to bump up to two 650CCA batteries before the boat goes in. Currently my batteries are the same MCA as your current one, so you will have no problem powering all you have, I'm bumping up my batteries because I fish offshore a bit and run a lot of electronics and just want to be safe, I always believe in going with the largest batteries you can fit in your boat.
 
Battery configurations are as disparate as which oil to run, but I have to disagree with running batteries in parallel when there are only two. Both batts supply more power in parallel, true, but more importantly they discharge together. If the alternator craps out with paralleled batts, the first indication you have may be when your electronics start shutting down or your motor won't start ... and by then you may be SOL. A boat spent the night off Charleston last year when this exact scenario occurred. By the time time they discovered the problem, the VHF wouldn't even work.

With a motor that doesn't exactly have a gorilla alternator (like Mariner, I believe), I'd run one battery as primary and one as an isolated reserve. Switch batteries as you will to equalize use, but BOTH (paralleled) should be reserved for emergencies only. BTW, modern switches are "make before break", and can be switched between batteries at will. DO NOT, however, SWITCH TO "OFF". You're always safe to switch with the motor off, of course. Perko and/or Blue Seas web sites should have wiring diagrams.

Starting batteries are fine if you don't have much of a drain, dual purpose might be a little better for your application, and nothing wrong with using two deep cycles. Starting batts don't do deep discharges very well, deep cycles don't like heavy loads but will tolerate typical starting loads OK. The keys to longevity is keep 'em charged properly, keep connections clean/tight, and keep 'em serviced. Lengthy application of chargers that don't disconnect at full charge have cooked more batteries than anything
 
Why is Grady using starting batteries, is it because they are the least expensive battery to select?
 
First I like to say again guys thanks for all your help. However I think Curmudgeon has more of the idea what I was talking about. I did not want to use both batteries at same time for more power ( which I assume would be a parallel configuration) . Do the fact gas is prob going to be like 9 Bucks a gallon by the time June hits. My plan was just to go out a short distance or so, kill my Engine, sit back with a beer and and pole and just relax for couple hours.

At which time I would turn a switch and only be using one battery soley deticated to my Marine Stereo and GPS/Fishfinder. So after a couple hours or more after running the Stereo and GPS all of a sudden they give out because I just killed the battery, than I can just turn the switch to the other battery which is deticated to starting my Engine. This way I can start up the boat with no problem at all.

Now I am understanding more about this dual battery setup with research, and the help from you guys. My next question is can I have my new West Marine starter battery that I bought to be hooked to the Engine, and than have a deep cycle battery as second battery with the Battery Switch? Or should you keep them the same type, either both batteries "starter" or both batteries "Deep Cycle" and not mix and match? For example putting a "starter" with a "dual purpose" or "dual purpose" with a "deep cycle". Thanks
 
My considered opinion, and agreement is not required.

I've run a deep cycle as the primary for 8 years now (2 different boats); I've got 3 years on the current batt without even a hiccup and everything runs off it. I've also an orbital backup starting batt that I use every so often in order to keep it charged. My reasoning is that if I need the second batt, it's most likely to start the motor so a starting will suffice handily. On the previous boat I ran two deep cycles, alternating every trip or so. Again, not a hiccup in five years.

You're not "mixing" batteries unless you parallel 'em (by switch or charger). In the event you had to in a starting emergency, the short duration required is insignificant. Otherwise, keep 'em separate and use whatever type you desire.

I'm a believer in KISS. Keep it simple and there's less likelihood of trouble, either mechanical or man-made. Remember, though, if it's in a boat or has boobs, sooner or later there will be trouble ... :wink:
 
After Looking at all my options I decided to go the newer system by getting the "Add a Battery Dual Circuit System" from Blue Sytems. It seems to be the best and most effective way for adding the two batteries eliminating the charging and balancing problem between the two batteries that could occur with the 1, 2, both and off switches. Thank you to everyone and all your advise.
 
Can't go wrong with the choice you made for a single engine boat.

Check battery water level periodically. Not a bad idea to get one of those cheap floating ball specific gravity test devices at your local auto barn. The ony way to know true state of charge.
 
Do a search for BEP and 716SQ100A. You can use a starting battery for the motor and a deep cycle for the electronics. When the starting batery is charged, it charges the deep cycle.

Deep cycles can start outboards just fine, they just cost more. I wouldn't want one on a big block Chevy or a diesel but outboards are not a problem.


And yes Grady is saving themselves money by not installing deep cycles where there is a dedicated house system.
 
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