2 Batteries and 3 switch setup - SAIL magazine

[Paul S]

Was just looking through the latest SAIL magazine. There is a good writeup on the 3 switch setup (which I installed on our M). Good reading. It is good to see that this setup is gaining in popularity.

It seems soooo much easier to work than the 1-2-none-both switch setup, IMO.

The BEP marine 3 switch/VSR setup I have apparently is being carried by Boaters world. West apparently doesn't carry it anymore. But of course you can just use 3 on-off switches and a combiner/vsr for the same effect.

Paul

[Frank C]

I read that article too. In the second part, he recommends the "Duane approach" of a dual-battery house bank, parallel for 12-volt batts of course. Our small outboards just don't justify dedication of 60 pounds of battery, and the benefit is that doubling the size of the house reserve can potentially triple battery life.

I've decided that's my direction and just punt on the starting battery - the Suzuki's starting demand is so slight that the house can easily supply it, even when low. I always carry the jump-start battery too, so that's my backup.

The only problem with creating a single bank is guaranteeing that the batteries are always on-line to the alternator ... means I need to assure that crew do not click-off the battery switch when the outboard's running???

[Paul S]

Yea..I wouldn't be able to sleep if I knew both batteries were online all the time. For my piece of mind, I like having them totally separate...Only touching the switches for additional power - generally for the inverter to power the real 110v coffee maker we have on board...then switching back after the coffee is made.

The Mac certainly can get away with one battery (and maybe a jump start power pack - just in case) for the most part. I would rather have a lot of redundancy. Other than weight and cost, there is not a lot of downside to 2 batteries that would outwight the benefit.

Paul

[Night Sailor]

I decided last year to install the three on/off switch setup recommended in the West Advisor's treatise in the 2005 catalog. I used three Blue Sea "mini"switches. One is for the start battery only. One is for the house battery bank of two batteries. The third is for combing all batteries if needed. they are all mounted together in the panel directly below the galley seat, at the head of the port side after berth cushion.

When I set out for a sail, the engine and house battery switches are turned ON, and left on unti lI return and I'm ready to leave the boat. Then they are turned OFF. Simple. I labeled the switches for identification by new crew. Even my 5 yr old granddaughter can read ON and OFFand MOTOR and HOUSE, so it's hard for anyone to make a mistake if a switch needs to be moved for some reason.

The motor maintains the charge on the start battery directly. The solar panel also when the motor isn't running. The start battery is combined to the house bank with a West Marine 50 amp battery combiner. When it has a full charge, then any charging current goes into the house bank until they are fully charged. Neither can draw from the other because of the combiner.

I haven't had a single issue with low voltage since I set that up. I highly recommend it.

[Bobby T.-26X #4767]

i've had a "1-2-none-both" switch and a West marine combiner between the two batteries since day one.
why do i need to change?
please enlighten me.

it always sits on 1 (the motor only battery).
the combiner allows both to charge while keeping 2 (the house battery) seperate.
if 1 (the motor only battery) ever failed, i switch to 2 (the house battery) as a motor starter back-up.

what am i missing here?
why is this not an accptable method for a standard outboard with two batteries?

seems most everyone is trying to talk me into changing to three on-off switches.

Bob T.
"DaBob"
'02X w/ '04 90 TLDI

[They Theirs]

It appears by combining the house and engine battery into a single battery system with an emergency start jumper in reserve, were extending the battery life by reducing the depth of battery drain on a single battery by doubling its capacity. Ill follow the Sail Magazine second battery option with Frank.

[Paul S]

i've had a "1-2-none-both" switch and a West marine combiner between the two batteries since day one.
why do i need to change?
please enlighten me.

it always sits on 1 (the motor only battery).
the combiner allows both to charge while keeping 2 (the house battery) seperate.
if 1 (the motor only battery) ever failed, i switch to 2 (the house battery) as a motor starter back-up.

what am i missing here?
why is this not an accptable method for a standard outboard with two batteries?

seems most everyone is trying to talk me into changing to three on-off switches.

Bob T.
"DaBob"
'02X w/ '04 90 TLDI

you do not NEED to change...there is just another way to do it out there (a 2 battery system).

The benefit of the 3 switch system is there never needs to be any interaction with the switches (unless you need to join them with the emergency switch). There is no human error, as no one wil be touching them on a regular basis. The house is powered by the house battery ...the motor by the motor battery.

There are millions of 1-2-n-b switches out there. I am not trying to convert anyone to the 3 switch setup...I just wanted to point out in the original message that SAIL magazine did an article on the idea. I like the fact that it is becoming a well accepted practice.

Paul

[Chip Hindes]

Bobby T: If you've described the wiring of your system accurately, you do not really have a "house" and "starter" battery per the normal definition. You have a single electrical system which is powered either by battery 1 or battery 2. So, for example, when your system is switched to "1" you're drawing your house loads off the "starter" battery.

Those who have the three switch setup essentially have two separate electrical systems: one for the motor and one for the house loads.

This West Marine Article explains it much better than I could.

Very interesting, several years ago this article recommended a Voltage Sensitive Relay rather than a straight combiner. It's been rather subtly altered to delete that reference now that they no longer offer a VSR.

[Catigale]

Im a 1-2-BOTH-NONE switch user - I guess I feel this is a place where you can overkill if you are just a few-day-at-a-time cruiser like me. Longest trip might be a week.

Motor on BOTH for charging, and switch to Battery 2 for Sailing. WHenever we transition, I send someone below to switch the battery. I can do it single handed if needed.

I guess if I were outfitting from scratch the always charging approach would make sense to implement, agreed.

Definitely agree that we dont need starter batteries - I use two Group 24s and a jump pack which I cleverly bought in the winter for the Admirals car - and rotate it into the boat for cruising in the summer.

[Bobby T.-26X #4767]

here is my set-up: single switch w/ west marine 50A combiner
it's the first one with the single switch.

i always leave my switch on 1 (starting battery). never's been a need to switch.
however, if my starting battery failed, i could switch to 2 (house battery) as a means to start the motor (i've tried this action several times and it works great).

i also have a small charger permanently connected to the house battery that will charge both batteries via the combiner when shore power's available.

but, i understand that the "hip & trendy" way to do this now is via three switches.

[Night Sailor]

The reason I went to the trouble and expense of changing from a single system with 1,2,off,both single switch was precisely the fact that someone had to remember to do the switching for the appropriate usage. Sailing on house, motoring on start. If forgotten, then you run batteries down too much.

The advantage I gained is I don't have to rely on my memory, or someone elses, to prevent draining batteries toless than %50 of capacity. And more important, twice, it was very handy safety wise to instantly start the motor and power out of the way when very high speed motor vessels with ignorant or belligerant skippers threatened my safety. No switches had to be changed because they were already on.

[Paul S]

here is my set-up: single switch w/ west marine 50A combiner
it's the first one with the single switch.

i always leave my switch on 1 (starting battery). never's been a need to switch.
however, if my starting battery failed, i could switch to 2 (house battery) as a means to start the motor (i've tried this action several times and it works great).

i also have a small charger permanently connected to the house battery that will charge both batteries via the combiner when shore power's available.

but, i understand that the "hip & trendy" way to do this now is via three switches.

I wouldn't call it hip and trendy It is just another way to do it. With this setup you wouldn't even have to move the switch from 1 to 2. Not that it is hard to do. But some human interaction is involved in moving the switch.

For decades the marine industry survived quite well on the 12nb switch. The Mac can be used quite well with one battery or one bank. I think it is good practice to use 2 banks.

[Bobby T.-26X #4767]

The reason I went to the trouble and expense of changing from a single system with 1,2,off,both single switch was precisely the fact that someone had to remember to do the switching for the appropriate usage. Sailing on house, motoring on start. If forgotten, then you run batteries down too much.

i believe that you're incorrect when you say that someone has to remember to switch.
look at the chart from the above link.
1 is starting battery. you can leave it there for all of eternity. with the combiner, when your motor is running, both batteries are being charged. no need to switch...
when you turn on the house lights, the house battery does all the work without affecting the starting battery. no need to switch. the starting battery always remains untouched. it's in it's own "bank".

the 12nb switch only controls what battery is being used to start the motor. it's for no other reason.

the only reason you would ever need to switch out of the 1 mode is if your starting battery failed. then you switch to 2 and the house battery will start the motor.

you can switch to both and both batteries will work together to start the motor if necessary (although you would probably never need to use this mode).

the 110 stand alone charging unit is connected to the house battery and will cherge both batteries via the combiner.

what am i missing here? there is truly very little need to ever switch.

[Chip Hindes]

when you turn on the house lights, the house battery does all the work without affecting the starting battery. no need to switch. the starting battery always remains untouched. it's in it's own "bank"...the 12nb switch only controls what battery is being used to start the motor. it's for no other reason.

True, but note that wired in this fashion, no matter where the switch is set, the house battery is permanently connected to the DC panel and cannot be disconnected without pulling one of the terminals off the battery or cutting the wire.

[DLT]

To help clarify this, I believe:

The common terminal of the typical 1-2-N-B switch of wired to the motor starter, motor alternator, and DC panel. Of course, motor starters and alternators are often wired together, such that they use the same wire.

Thus, if you had the motor running, you could power your DC panel, even if the switch is in the None/Off position, or there were no batteries. Subject to charging capacity versus load issues, of course.

The "1" and "2" terminals are typically connected to the different banks.

So, most people switch to "1", which is typically the starter bank, and start the motor. Then, they may switch to both, to charge both banks off the motor. After they shut the motor off, they switch to 2, to run the house off the second bank.

There are all kinds of variations on this... For example, some motors may be wired directly to the starter bank. But, I believe this is the basic "traditional" method.

These charging relays/combiners simplify this somewhat by allowing you to wire the motor straight to the starter bank and only the DC panel to the switch. In this case, most people probably leave the switch in the "2" postion, relying on the relay/combiner to charge the house bank when the motor has charged (or is charging) the starter bank.