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The whole reason for running 2 batteries is for redundancy and safety. Most dual battery switches have 4 positions, Off, 1, 2 or Both batteries. My question is : Should you run the battery switch with the number 1 battery on, or the number 2 battery only or in the Both position?

I was stuck 10 miles off shore in Mexico in a friends boat because his thoughts were to run both on at the same time all the time. Well he forgot to check his terminals and both batteries went dead. With no one in site, we waited an hour and luckily someone came by and gave us a jump.
I recently ran across another boat owner who had a similar problem because of connector problems and running both batteries at once.
The answer to me seems like you should run with only one if they both have a full charge. Just to set the record straight...what is the best way to set the switch will running??
RD
 

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Reefdiver,

I will look forward to some answers to your question. However, in general I believe I've been told to run only one at a time, not both. I guess my question is why the "Both " switch at all?

Rusty
 

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Great question. I was thinking of putting a dual battery set-up in my boat, and wanted to know the answer to the exact same question(s)!

What Luck! :wink:
 

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I will let someone else give you the entire dissertation on this situation, but in short, here goes:

NEVER NEVER NEVER NEVER NEVER NEVER

Did I say never?

Flip the red switch through it's different stations while the boat is running.

Sorry for the confusion. Someone else understood what I meant. You can go A-B but not 'Off' while the motor is running.

You will cook the alt. and I believe the voltage regulator.

No, fortunately I did not learn the hard way, but a buddy of mine did. Long story short, he was delivering a sailboat back to the mainland from Hawaii after our race over and about 1000 mile out of Astoria when the rudder broke and then let's just say things got even worse and flippin's the switch to 'off' while the motor was running was just one of the events. This is a very bright guy who I have several thousand ocean racing miles with and he is now ship captain currently stationed in Kaneohe, HI.

Even the best crash and burn on occasion.

House batteries are a great thing.

[ 09-18-2003, 09:32 PM: Message edited by: Redbull ]
 

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I hate to ask, but that message sounds like a lesson learned the hard way?

I have to install a second battery on the EK due to fancy GPS unit. Can't take the voltage coming off my merc.

Hopefully an expert can chime in here.

EK

[ 09-18-2003, 03:09 PM: Message edited by: El-Kabong ]
 

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Redbull, you seem adamant about not switching while the motor is running. But I thought the entire reason for having an A - A/B - B switch sequence was to allow you to do just that. Why would it cook the alternator? There's no interuption in current. Now I'm confused.
 

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I think it should be in the both position. That way the battery isolator can charge the weakest battery. Faulty wiring will stop you no matter which position you have the switch in. A good policy is to disconnect the battery power from the boat wiring when not in use. The big problem is electrolysis, and by disconnecting the battery you slow the process down. Battery wiring should be inspected on a regular basis,another good trick is to mix baking soda and vasoline together. Use this mixture to coat your battery terminals.
 

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While roaming around the Perko (battery switch maker) web site I found this

"CAUTION: (1) Make sure connections at terminals No. 1 and No. 2 are the same polarity.
(2) Always STOP engines before switching to "OFF" position.

Make-Before-Break feature allows switching between 1-all-2 positions with running engines."

Sounds like going to OFF is the real problem and, at least with Perko switches, you can go from A to B.

EK
 

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On a sort of related note was wondering if anyone had come across (and how they solved) this problem.

Have a '89 60hp Merc. which I have come to discover has no voltage regulator. Enter new fancy Garmin GPS unit.

When I accelerate the 60hp, the GPS shuts itself down with the message. Voltage Too High, Shutting Down. Which it then does, much to my dismay, as I was kinda counting on the depth information.

So the only idea I have is a second battery.

Anyone come up with a more creative solution?
 

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All,
I have this set up in my Duckworth and I have had the same two marine batteries in the boat for 5 years. Both Batteries test perfect every year. I alternate between the two batteries every other trip. This method keeps both batteries up and fresh, and if a charging system problem occurs, it affords you the time to get to the dock should you use up one of your batteries. As mentioned in this topic your should NEVER switch the battery selector to off while the engine is running!!! If I understand the circuit correctly, selcting the off position on the battery selector will force the alternator to overload because it has no where to send the charge. LuckyDuck1
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The worst day fishing is always better than the best day working!!!
 

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I run my Perco switch on 1 or 2 never all. I try to alternate which battery I use each time I use the boat. My understanding of the All setting is if each individual battery did not have enough juice to start your motor both combined may start the motor. I like the idea of having one fully charged battery isolated from my boats electrical system so that I always have a backup.

I was puzzled by the comment that someone was runing a GPS directly off the Merc alternator??? My alternator goes directly to the batteries and I have a main line to my fuse block where my GPS/Sonar wiring is connected. When in doubt about these things I contact Rogers Marine Electronics on Marine Drive. They are the best I've found.
 

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Couple more dead batteries and after having the same set up for 15 years, finally got a reasonable explanation from our local mechanic.

We always started and ran on "both". Our mechanic stated that this generally doesn't get a good charge to one or the other of the two batteries. His recommendation is to always start, and run on battery "A", then the next time out, start and run on battery "B". This accomplishes two things. You really get positive charge going into each battery seperate, instead of trying to split the charge up. (Makes sense to me). This also allows you to monitor if you have one bad battery creep up on you. By starting and running on "both" you may have a low charge on one or both of the batteries, but not know it until too late. The only time to use "both" is when for some reason you have a low battery and need the extra oomph to get the motor started when you are away from the dock.

Mike
 

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Battery 1 should be your primary battery. If you are sitting anchored somewhere, switch to battery 2, run all your electronics or whatever else you have coming off your battery system. When you go to leave for the day, switch to both. Your engine will start from the most charged battery. You will charge both batteries to their max capacity while going back to the ramp, as long as you run long enough. Your system will charge the most drained battery first and once the voltages are equal, both batteries will charge at the same rate.
 

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West Marine sells a thing called a battery combiner. It is smart battery charging, the combiner looks at each batt and always keeps the batt that is the lowest charging..It won't let you run both batteries down, that way you don't have to remember which batt the A-A/B-B-off, switch should be on, if any of you out there are like me it's very easy to forget about the batt switch....The west Adviser in their catalog or web site tells all about it. Duel Battery charging :cool:

quote from west marine
What's the solution?
We strongly recommend that you select and wire your batteries differently from the way the factory wired them. Use a stout starting battery to crank your engine, based on your engine's cranking requirements. Use a larger house battery with triple the capacity of your daily DC requirements. Now this is where it gets complicated: we DON'T recommend the use of a traditional OFF-1-BOTH-2 battery switch. Instead, consider using three OFF-ON battery switches as follows: one switch to connect your starting battery to your starter circuit; one switch to connect your house battery to your boat's distribution panel; and one switch to parallel your battery systems if either battery fails.

With this switch set-up, you simply turn your engine and house switches to the ON position whenever you are onboard, whether anchored, starting your engine, or sailing. The battery parallel switch remains OFF unless there is a complete failure of either battery bank or you have run your starting battery down trying to crank a reluctant engine. When your engine is off, the starting battery is safely isolated from the house loads. It cannot be discharged, even if you leave your stereo on all night, listening to Jimmy Buffett and blending margaritas.

How do I charge both banks simultaneously?
By isolating starting and house banks, you face a challenge trying to charge them from a single source like single-output chargers or alternators. If you violate the "separation" of the two banks, you face the probability of two dead batteries due to "operator brain-fade". That's why we are great believers in the West Marine Battery Combiner and Heart Pathmaker, Balmar Dual Output Alternators, and to a lesser degree, battery isolators. These products sense the voltage of the battery banks and connect the batteries together whenever one battery's voltage is elevated. Both banks charge simultaneously and remain combined until the voltage drops, whereupon they are disconnected from one another. It's much like having a very attentive engineer flip your battery parallel switch on and off at exactly the right moment. The result is maximum charging performance for two banks, and complete isolation of the two banks to ensure that you can start your engine.

[ 09-18-2003, 05:47 PM: Message edited by: Wright Angle ]
 

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Plug Cut,

" was puzzled by the comment that someone was runing a GPS directly off the Merc alternator??? My alternator goes directly to the batteries and I have a main line to my fuse block where my GPS/Sonar wiring is connected."

never said I was running GPS off alternator. which could explain why you are puzzled. :wink:
GPS is hooked up to forward switches which are connected to battery.

When 60 is throttled up, I get the message on the GPS.
 

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Battery combiner or battery isolator,they are the same thing. These devices are a must have with two batteries. It's a transistorized unit that picks the less charged battery and applies a charge. It doesn't make much differance which battery you select,1 or 2 or both. The isolator only charges one battery at a time. ElKabong,sounds like your motors electrical system is putting out more than 14volts. I'd call the Merc. dealer and ask a few questions.
 

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Run one at a time. That way you keep at least one charged up at all times and you should have another for backup. Switch from "!" to "2" mid day. That way everything gets worked every so often.

Unless I am missing something, if you run the switch in the "Both" position your 12V becomes a 24V-Not a good thing.

Run one down charge it up and switch. Repeat.

Mark and the "Hey, that's what the guy at Stevens told me" dog.
 

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freespool,

I talked to the guys are Stevens yesterday. They suggested 2 batteries.

Ek
 

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Flatfish,a duel battery set up is two 12 volt batteries hooked up in parellel or positive hooked to positive. What your refering to is two 12 volt batteries hooked in series or positive hooked to negitive which would give you 24 volts and a lot of burned up equiptment. ElKabong I'am not sure what they told you. If your motor is putting out more voltage than your fish finder likes,I can't see what two batteries will do. The battery isolator will only charge one battery at a time. Do you have a shop manuel for your motor?
 
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