1/2/Both switch bust?

[LadyInBed]

Vic's 'American' system is more or less how my 1-2-B system is used, as both 12v banks are about 130ah. Sometimes I initially switch to 1, start engine and continue to run domestic on 1, the next time I go to the boat I might switch to 2. The only time I switch banks to start the engine is after a longish passage, especially a night one when the solars aren't feeding the batteries, or having spent a few days on anchor without much sun.
Why anyone would want to turn a bank off whilst onboard is beyond me, as is turning a 1-2-B switch through Off to get from 1 to 2.

 

[solent clown]

Make sure you do not inadvertently switch both to off while the engine is running.

A good procedure to follow:

When ready to start the engine switch the domestic battery off and the starter-battery on

Start the engine

Allow the starter battery to recharge and when done ( indicated by ammeter and/or voltmeter)
switch the domestic battery on THEN switch the starter battery off.

Keep the domestic battery on until not needed or you need to start the engine again

When next starting the engine switch the domestic battery off and the starter battery on.

Repeat the above sequence​

Golden rule: Only the skipper is allowed to operate the battery switches!

All good advice, though with our small demand on the house battery - radio 4 on the stereo, and the VHF - which is currently hard wired, we do not differentiate between the two small identical batteries as house or starter. We use one battery one day to do both tasks, one the next. Once the engine is running we put both on charge. It works for us, and unusually, it is Karen's job to look after the batteries as she gets mad if she cannot listen to The Archers.
As written by others here, most important is to have the routine what works for your individual set up and situation.

 

[PaulRainbow]

Of course you can spend a lot more money on a non 1-2-b system to make give you something with more points of failure but that does provide the idiot proof system that you and your crew clearly need.

That's just nonsense. A BEP 1-2-B is £94, three BEP on/off switches are £75, plus £32.50 for a Victron VSR = £107.50, a difference of just £13.50, hardly "a lot more money."

More points of failure ? A switch could fail, but it wouldn't matter, use the emergency switch, what do you do with a failed 1-2-B ? The VSR could fail, so what ? If you connected the alternator to the engine battery (or left it where it was to start with, the battery terminal of the starter motor) then the alternator keeps charging the engine battery and you use the emergency switch if you need to charge the domestics.

Why do you always decry this arrangement, whe it is what you have on you "other" boat ? Why not have a 1-2-B on the "other" boat ?

 

[jmad]

Hello,

New to this thread so please don't bite my head off can see some heated opinions and it's really a bit new to me.
Have a Sadler29, 2 batteries the same type, and an 1/2/Both switch. I usually have both for starting and whilst running, then just number 2 when the engine is off.
What is wrong with this? Please help me understand I really don't !!
As a backup do do carry a heavy duty jump start box, for peace of mind!


Also to VicS or anyone who cares to enlighten ;-) me...

"A good procedure to follow:
When ready to start the engine switch the domestic battery off and the starter-battery on
Start the engine..."

So when I want to start the engine, all of my domestically connected consumers would be off?
What about NAV lights, RADAR and coms, presumably you wire all to the starter battery then? or???

Not being pedantic, just massively missing the point.

 

[PaulRainbow]

Hello,

New to this thread so please don't bite my head off can see some heated opinions and it's really a bit new to me.
Have a Sadler29, 2 batteries the same type, and an 1/2/Both switch. I usually have both for starting and whilst running, then just number 2 when the engine is off.
What is wrong with this? Please help me understand I really don't !!
As a backup do do carry a heavy duty jump start box, for peace of mind!


Also to VicS or anyone who cares to enlighten ;-) me...

"A good procedure to follow:
When ready to start the engine switch the domestic battery off and the starter-battery on
Start the engine..."

So when I want to start the engine, all of my domestically connected consumers would be off?
What about NAV lights, RADAR and coms, presumably you wire all to the starter battery then? or???

Not being pedantic, just massively missing the point.

Vics post was regarding a different arrangement to yours, so disregard that.

Regarding how you use your setup, starting the engine with the switch to both has two possible issues, firstly, the resultant voltage drop may cause your nav equipment to reset, depending on how senstive the equipment is and how low the batteries are. Secondly, you could be wasting valuable domestic power starting the engine.

All of the time the switch is set to "both" all of you batteries are connected together. So, certain problems could discharge all of the batteries, leaving you with no way to start the engine. Also, if you forget to change back to "2" you could sit at anchor and flatten all of the batteries, again no way to start the engine.

Worse case scenario, you're motoring along with the switch set to "both". One battery fails and flattens the other battery. You are unaware of this, as everything is running from the alternator. You stop and switch the engine off, all of the electrics go off too. You call for help on the VHF, actually, you can't, the batteries are flat

Engine batteries are for starting the engine (the clue is in the name ) Domestic batteries are for everything else.

IMO separate circuits are the way to go, i've posted that on here enough times, a search will bring up a few threads But if you don't want to make too many changes/spend too much cash, here's what i would do, in your case : Never use "both" except in an emergency, then set it back to "1" or "2". Use "1" one day and "2" the next, or "1" to start and run for a short while, the "2" for the rest of the day. Better yet, if you don't want to change the switch, fot a VSR, which will ensure both batteries get charged, then use whatever battery you fancy. In fact, you can fit the VSR and almost always use the same battery, keeping the other as the emergency battery.

 

[Saltsail]

Make sure your cables connected correctly! I had same issue.

 

[RupertW]

Why do you always decry this arrangement, whe it is what you have on you "other" boat ? Why not have a 1-2-B on the "other" boat ?

I stand corrected on the price for all the different components and wires you need for your preferred arrangement- last time I bought a 1-2-b it was a third of that price and a long time ago.

But I’ve never decried a VSR style arrangement - I’ve got one. What I always decry are people who declare that a simpler arrangement doesn’t work or is a bad idea always. You’ve never fallen into the trap of saying that it’s old fashioned but seemed to be fixed on one solution for small to medium yachts and I worry about that in an expert in any field.

 

[pvb]

But I’ve never decried a VSR style arrangement - I’ve got one. What I always decry are people who declare that a simpler arrangement doesn’t work or is a bad idea always. You’ve never fallen into the trap of saying that it’s old fashioned but seemed to be fixed on one solution for small to medium yachts and I worry about that in an expert in any field.

PaulRainbow may not have, but I freely admit I've often called 1-2-Both switches "old fashioned" or "antiquated", and I sincerely believe they have no place on a boat in the 21st century. Not because they don't work, but simply because they have the potential to be set wrongly and flatten the start battery. There's enough to fiddle about with whilst sailing without remembering to go down and change the 1-2-Both switch! Just having one on/off switch for the engine and a second on/off switch for the domestics is so much easier and totally foolproof. As for VSRs, they are just one solution. Another solution - which I favour - is the low-loss splitter.

 

[lpdsn]

PaulRainbow may not have, but I freely admit I've often called 1-2-Both switches "old fashioned" or "antiquated", and I sincerely believe they have no place on a boat in the 21st century.

I'm sure I've also used similar phrases. It's a debate that's been had so many times that it is not really worth having again*. However, when comparing them to a more modern arrangement there always seems to be so many constraints, limitations and risks that just disappear.

For example, there's a debate further up about the effect on the instrumentation of starting the engine. Starting my engine has zero impact on my instruments - I just don't even need to think about it. And I bet I'm starting a bigger engine with a smaller battery than most of the custodians of the 1-2-Both switches.

*I'm just about to go out for the evening but if anyone wants to restage the debate in my absence feel free.

 

[pvb]

I'm sure I've also used similar phrases.

Ah, but have you had the accolade of VicS accusing you of "bias"?

 

[steveeasy]

Well ive got three independent switches on my boat. Although ive not got my head round the set up yet( its on my list) I use the engine to start and shut it off when I turn the engine off. the domestic is that, and for the life of me I cant remember what the dam one is in the middle, I don't touch it.

Anyone know of a simple wiring diagram for this 3 switch set up?. can a VSR be incorporated in to a 3 switch system ?.

Thanks

Steveeasy

 

[pvb]

There's no real need to isolate the engine battery when you turn the engine off, only when you leave the boat.

The middle switch may well parallel the engine and domestic batteries.

Here's an old diagram I did for someone else...

 

[steveeasy]

There's no real need to isolate the engine battery when you turn the engine off, only when you leave the boat.

The middle switch may well parallel the engine and domestic batteries.

Here's an old diagram I did for someone else...

Thanks very much. Very clear and concise. Ill Check my Layout when I'm next on board.

Steveeasy

 

[steveeasy]

There's no real need to isolate the engine battery when you turn the engine off, only when you leave the boat.

The middle switch may well parallel the engine and domestic batteries.

Here's an old diagram I did for someone else...

Hi PVB
looking at the diagram, If no VSR is fitted, how does the engine battery receive a charge?.

Steveeasy.

 

[pvb]

Hi PVB
looking at the diagram, If no VSR is fitted, how does the engine battery receive a charge?.

In the diagram, isn't the alternator connected directly to the engine battery? That's a clue.

 

[PaulRainbow]

Thanks very much. Very clear and concise. Ill Check my Layout when I'm next on board.

Steveeasy

You will have a split charging arrangement, either a VSR or a diode pack. A good place to start would be to follow the thickest red cable from the alternator, where does it go ?

Your 3rd switch could be an emergency start switch, it could also be a negative switch, which is usually black.

What's the boat ?

 

[steveeasy]

In the diagram, isn't the alternator connected directly to the engine battery? That's a clue.

Err ok, I meant the domestic battery. the only Feed is via the VSR unless I am confused

Steveeasy.

 

[pvb]

Err ok, I meant the domestic battery. the only Feed is via the VSR unless I am confused

Seems like you are confused. OK, the idea of a VSR is that it only closes and transmits current once the first battery has reached a certain voltage. So the engine starts, the alternator recharges the tiny amount of power used to start the engine, then the VSR closes and the alternator's charge is connected to both the engine and the domestic batteries. When the engine is stopped, the VSR opens and isolates the domestic batteries from the engine battery, so that using the boat's equipment won't discharge the engine battery.

 

[steveeasy]

You will almost certainly have a split charging arrangement, either a VSR or a diode pack. A good place to start would be to follow the thickest red cable from the alternator, where does it go ?

Your 3rd switch could be an emergency start switch, it could also be a negative switch, which is usually black.

What's the boat ?

Hi,
No VSR and I don't think it has a diode pack whatever that is. Just a 28 footer and looks well done in terms of installation. the distribution panel were ripped out along with other stuff before I bought her.

Steveeasy

 

[steveeasy]

Seems like you are confused. OK, the idea of a VSR is that it only closes and transmits current once the first battery has reached a certain voltage. So the engine starts, the alternator recharges the tiny amount of power used to start the engine, then the VSR closes and the alternator's charge is connected to both the engine and the domestic batteries. When the engine is stopped, the VSR opens and isolates the domestic batteries from the engine battery, so that using the boat's equipment won't discharge the engine battery.

Normally am confused, But take the VSR out of the equation, how could the domestic battery receive a charge ?.

Steveeasy