Single or dual battery for an 18' dual console?

GeorgeKohler

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I think dual batteries are a good idea for small boats if you can do it. I have always had dual batteries, and just alternate day by day on which one I'm running on, so the other was the backup plan if the battery died. But Jimmy and I are sorta preppers, so we always have a backup plan to the backup plan. We also carried a small jumper pack that we kept plugged in so it was always charged.

I might add we 've NEVER been stranded due to a dead battery.
 

Cam

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Always had dual batteries. What I used to do was, when I went out, I ran on one and when I returned, I switched to the other. Never had a dead battery problem.
 

Bill D.

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BTW--Brian, don't worry should you ever get stranded because of a dead battery. Just be sure to tell us about it and trust that none of us will say, "told you so". <grin>

One other thing, none of us have ever seen a person at the boat ramp after launching go pull their vehicle battery ''cause their boat battery was dead.
 

HOGAN

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No need for two batteries on that size boat. I have one on my 18' Scout, and it's all I need. Will your alternator provide enough power to charge 2 batteries?
 

LouC

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As long as you are willing to use the typical 1, 2, both, off battery switch correctly, there is no problem keeping 2 batteries charged properly. Never leave it on both unless both batteries are discharged and you need both to get it started. Alternate #1, then #2. If not you may want to use a battery combiner. I've had 2 batteries and the switch for 15+ years with very few problems.
 

WALSHIE

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I have two batteries on my 18' CC and quite frankly, one has been dead all year so it was useless.....didn't get stranded with just one battery.
I re-wired my entire boat though so I know EXACTLY what's going on and no leakage. Since I'm wired for two, I will probably replace the dead one this year but one is fine.
 

Gregory S

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my son in Law just bought his first boat, a Nauticstar 2302 legacy center console. it came with two batteries and a 1, 2, both, off switch. My advice to him was run out on one , fish with that battery and switch to # 2 for the start up and way back. Not much in the way of house load in those boats other than fish finder, and radios.
 

HOGAN

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my son in Law just bought his first boat, a Nauticstar 2302 legacy center console. it came with two batteries and a 1, 2, both, off switch. My advice to him was run out on one , fish with that battery and switch to # 2 for the start up and way back. Not much in the way of house load in those boats other than fish finder, and radios.
If he does it that way, the #1 battery will have drained down, and will not be recharged on the way back.
 
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speedo

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In my SeaRay I had two, two-battery banks (4 total) and a 1, 2, both, off selector. I always ran the boat with "both" selected so all four were getting charged. When I stopped running, I'd choose 1 or 2 for the night's house load. In the morning, I had one bank in reserve if necessary. If I was on the hook for more than one day, I still kept the switch on the same "house" bank I'd chosen earlier. Never ran out, and always had the second bank in reserve.
 

Brian N

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I am probably going to go ahead and re-install the second battery with a 1, 2, both switch. I'll also add an onboard charger to plug in when the boat is in the yard to keep everything topped off. I'll definitely need some assistance on wiring it, so that will be another thread...
 

speedo

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Brian, I always monitored the levels of both banks and they were always "topped off". I guess if there's a weak link, i.e. one battery going bad, you could drain the good battery on "both" but that was never an issue for me. Switch "Off" when not on the boat, "Both" when running and 1 or 2 when on the hook or fishing with an electric trolling motor. Both charging from alternator when running, and only one discharging on the hook or fishing. The other in reserve. As long as both batteries are in good shape, I don't see a problem. Easy enough to monitor individually at rest and when charging.
 
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Phillbo

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If he does it that way, the #1 battery will have drained down, and will not be recharged on the way back.
You are correct in position #2 only battery #2 is getting charged. In position #1 both batteries are getting charged. At least that is how it works on my cruiser. I start and run on #1, switch to #2 when on the hook and then back to #1 in the morning to start and run....... never have an issue even when on the lake for a week.
 

speedo

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You are correct in position #2 only battery #2 is getting charged. In position #1 both batteries are getting charged. At least that is how it works on my cruiser. I start and run on #1, switch to #2 when on the hook and then back to #1 in the morning to start and run....... never have an issue even when on the lake for a week.
Similar to what I did. On "both" while running, charging both. On 1 or 2 when on the hook, leaving the other in reserve.
 

Phillbo

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I have never used "Both"... Position #1 charges both batteries.

#1 batt - Starting Batt
#2 batt - Deep Cycle Batt for House.
 

Bill D.

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Phillbo

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I have some kind of isolator thingamajig baked in according to my mechanic. I don't pay much attention and just continue to follow my routine that has worked well for me for years.... If it aint broken, don't fix it..
 

Bill D.

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I have some kind of isolator thingamajig baked in according to my mechanic. I don't pay much attention and just continue to follow my routine that has worked well for me for years.... If it aint broken, don't fix it..
That makes sense. I used the same system way back in the late '70's with a truck/camper. Your isolator lets the alternator recharge your house batt, but protects your starting batt from draining down and the risk of not be able to start the engine.
 

LouC

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I have simply alternated use of both batteries by the day I use the boat. That way they both get charged but not at the same time. I don't think a typical inboard gas alternator is intended to charge 2 batteries at the same time. I'd think an outboard charging system is even less so able to. If you are having battery troubles always check for parasitic drains. I had the auto restart function enabled on my GPS/Fishfinder and it was killing batteries until I was sitting on the boat one day with everything off and sure enough the thing turns on by itself! Then I got a meter and could actually measure the draw and BTW, if you have one weak battery and put it on both as a test you can also measure the bad battery pulling juice out of the good one. So check for parasitic drains if you have battery problems before just replacing. Each season I make sure that function is turned OFF.
 
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