Battery switches - 4-way vs key-type

[syvictoria]

Hi. I'm about to embark on re-wiring the boat, plus installing new batteries and solar panel(s), and so I'm afraid that this could be the first of many questions! (although I do have my bible to hand... Nigel Calder's book!)

The current set-up has a Vetus 4-way selector switch and a red key-type isolator switch built into the switch panel, which I need to upgrade (it only has 8 switches/circuit breakers and I'd like to have a 'one switch - one job' set-up). Is the key-type selector actually necessary, or is it simply duplicating the selection of the house batteries?

Thank you!

 

[VicS]

when you say a 4 way selector switch do you mean a 1, 2, both, off switch?

If so that would normally serve as battery selector switch in a two battery system as well as the isolator.

More information need about your existing system and what you hope to acheive is really needed.

If you have Calders book you would be best advised to follow his suggestions rather that to attempt to mix in ideas from other people or other books.

The keyed switch may have been introduced as a security device .. depends how its wired and what it does

 

[syvictoria]

Thanks very much for your reply VicS, and sorry for the delay in mine.

Yes, I do mean a 1, 2, Both, Off switch. The cable then goes directly to the key-type switch which is built into the original (builder logo'd) switch panel with circuit breakers. I need to add further switches, and the wiring behind is the usual nightmare, hence my plan to replace the panel.

I'm inclinded to do away with the key-type switch. Is it really a help security-wise? The red plastic keys aren't that hard to come by, after all!

Thanks again.

 

[ghostlymoron]

Hi. I'm about to embark on re-wiring the boat, plus installing new batteries and solar panel(s), and so I'm afraid that this could be the first of many questions! (although I do have my bible to hand... Nigel Calder's book!)

The current set-up has a Vetus 4-way selector switch and a red key-type isolator switch built into the switch panel, which I need to upgrade (it only has 8 switches/circuit breakers and I'd like to have a 'one switch - one job' set-up). Is the key-type selector actually necessary, or is it simply duplicating the selection of the house batteries?

Thank you!

To have a seperate switch for each device is ideal but you may finish up with an unfeasibly large panel unless you combine some of them. Each circuit must be seperately fused though. Don't forget to allow for additional fused switches for gadgets that haven't been invented yet.
I am a strong advocate of auto switchover for charging your batteries using a VSR but you could retain your 1-2-B switch for selecting usage in an emergency.
Agree with Vic that it's best to pick one horse and ride it. I don't have Nigel Calder's book so don't know what he recommends.
It's best to have a labelled terminal rail behind the panel. And good idea to leave a draw cord in any hard to reach areas where the wiring runs.
Hope I'm not teaching Granny to suck eggs.

 

[nickd]

if you can put a seperate charging system in, then I would get rid of the 4 way and replace to 3 key switches.
I have three keys, engine battery on/off, Leisure on/off and join leisure to engine on/off. The join key switch has no key in it which means it is now very difficult for any guests to inadvertantly flat my engine battery.

 

[Talulah]

You really need to investigate the wiring further.
Following on from a previous post our 1,2,Both,Off switch purely relates to starting the engine. It has absolutely nothing to do with anything else.
There are then two seperate master key switches.
One for domestic battery out. One for Bow thruster out plus a couple of breakers for Windlass and SSB.
Charging from shore power and alternator doesn't go through any of these switches.
Eberspacher goes directly to domestic bank.

However, on a lot of set ups the 1,2,Both, Off switch not only relates to engine starting but also to charging. So you need to investigate exactly the current set up.

 

[ghostlymoron]

You really need to investigate the wiring further.
Following on from a previous post our 1,2,Both,Off switch purely relates to starting the engine. It has absolutely nothing to do with anything else.
There are then two seperate master key switches.
One for domestic battery out. One for Bow thruster out plus a couple of breakers for Windlass and SSB.
Charging from shore power and alternator doesn't go through any of these switches.
Eberspacher goes directly to domestic bank.

However, on a lot of set ups the 1,2,Both, Off switch not only relates to engine starting but also to charging. So you need to investigate exactly the current set up.

My friend VicS sent me a wiring diagram of the 1-2-B switch

which /i have kept for reference.

 

[Talulah]

My friend VicS sent me a wiring diagram of the 1-2-B switch

which /i have kept for reference.

The one battery set up in the diagram is the simplest. However, you could quite easily flatten the battery through domestic usage. Net result you can't restart the engine to charge the battery.

The two battery set up in the diagram is the next simplest. You are using either one or the other battery to do everything. If you flatten the one battery you can switch to the other.
However, unless you frequently switch between 1 and 2 you could find the other battery hasn't been charged for a while and has gone flat through natural discharge. It also has the possibility of accidently setting the switch to the off position whilst the engine is running and blowing your alternator.

This is why people introduce bridging diodes or voltage sensative relays etc etc.
It starts to get more complicated.

 

[Tranona]

The simplest way is to chuck all that and use a BEP Marine switch and VSR cluster which has a separate isolator for each bank, a parallel switch so that you can start the engine with the house battery and a VSR to automatically deal with charging both banks with priority to the engine start battery. Switches are removable if you worry about security.

Fused supply from the house bank to the domestic distribution panel with separate fused circuits for services. You can buy ready made panels or build your own. On one boat I had Merlin design the circuits and supplied most of the hardware but indulged in a high class custom made distribution panel from Taplin. All much easier than trying to suss it all out yourself. www.power-store.com for information.

 

[Talulah]

The simplest way is to chuck all that and use a BEP Marine switch and VSR cluster which has a separate isolator for each bank, a parallel switch so that you can start the engine with the house battery and a VSR to automatically deal with charging both banks with priority to the engine start battery. Switches are removable if you worry about security.

Fused supply from the house bank to the domestic distribution panel with separate fused circuits for services. You can buy ready made panels or build your own. On one boat I had Merlin design the circuits and supplied most of the hardware but indulged in a high class custom made distribution panel from Taplin. All much easier than trying to suss it all out yourself. www.power-store.com for information.

+1. But subject to budget of course.
You'll have to fill out your profile more of what boat, location etc. Maybe there is someone in the neighbourhood who can take a look.

 

[VicS]

I thought the hand writing looked familiar.

It shows how a 1,2,B switch is used in the simplest way as a method of selecting which, or both, of two batteries is in use and charging.

The red-key switch might have been the simple isolator before a second battery and the 1,2,B switch were added.

We have no idea at the moment how it is used in the present set up.
It could be simply duplicating the OFF function of the 1,2,B switch. It could be in the feed to just the domestic panel. Possibly even in the feed to/from just the engine. Or used in some other way.

Even the 1,2,B switch might not be wired and used as shown in my diagram.

 

[ghostlymoron]

The simplest way is to chuck all that and use a BEP Marine switch and VSR cluster which has a separate isolator for each bank, a parallel switch so that you can start the engine with the house battery and a VSR to automatically deal with charging both banks with priority to the engine start battery. Switches are removable if you worry about security.

Fused supply from the house bank to the domestic distribution panel with separate fused circuits for services. You can buy ready made panels or build your own. On one boat I had Merlin design the circuits and supplied most of the hardware but indulged in a high class custom made distribution panel from Taplin. All much easier than trying to suss it all out yourself. www.power-store.com for information.

Agree Tranona, that's the simplest but also the most expensive. Possibly just add a VSR and use the 1-2-B for distribution so he can use the house battery for emergency starting.

 

[Tranona]

Agree Tranona, that's the simplest but also the most expensive. Possibly just add a VSR and use the 1-2-B for distribution so he can use the house battery for emergency starting.

If you are keeping the boat you will bless the day you chose to do it well!. Did not need the fancy panel, but the switches and VSR are not hugely expensive.

 

[dedwards]

Firstly, if you have a 1/2/off then your current setup is basically the bottom drawing. (though you may have extra stuff added on)

You seem to be confused whether the key switch is an isolator or selector. The key switch will not be selecting anything but will simply be making/breaking a circuit somewhere. Where this break happens will affect what it does. eg, it may isolate the entire electronics or it could just be wired into the engine feed.

There is no real need for the key switch but some people find them useful for security/fool proofing reasons.

The 1/2/Off system is very common and works well but modern thinking is moving away from them to the 3x isolating switchs + VSR layout that others have mentioned. The main reason is that with the 1/2/0ff you need to switch to 'Both' when the engine is running to charge both batteries and then to the house battery when the engine is off to stop you flattening the engine battery. The VSR system does this automatically.

Now, you have mentioned solar panels and that makes things a bit more complicated as you will need to decide where you connect the solar panel. Many people wire theirs directly to the house battery.

 

[syvictoria]

Hi. Thank you for all the replies! If only things weren't so confusing...!

The second battery and 1, 2, Both, Off switch are original optional extras according to the boat's original invoice. The key switch was, I would imagine, a standard option. As I mentioned previous, the combined switch panel has the boat builders details on.

I'm vague about how thing's work as we've not yet had the boat in the water since we've owned her, and hence I don't unfortunately have a working knowledge of the current system. The previous owner had wired his nav instruments into a separate unswitched fuse box, but I'd rather that our replacement gear (the original gear was stolen prior to us purchasing the boat) was incorporated into a switch panel with circuit breakers. However I haven't been able to figure out a sensible system that only uses 8 switches...

I was striving for the second diagram, and I was intending to connect to solar panel(s), via a regulator, to the house batteries (probably 2 x Trojan 6v, but still to be purchased). There are currently only two batteries, one 105Ah and one 95Ah, and so I suspect that the previous owner may have alternated between them. I intend to have a dedicated engine battery. Sadly the previous owner passed away, and so I'm having to do a bit of guessing.

We're trying to work on KISS principles throughout the boat (a Victoria 30 BTW) - less to go wrong, easier to maintain, etc. We will be living aboard and cruising.

Thanks again!

 

[VicS]

You can dedicate the two batteries to engine starting and to house services and still use the 1,2 B switch but its up to you then to remember to switch from one to the other as and when necessary.

For example. Before starting the engine select the engine start battery, start the engine. Allow the battery to recharge then switch to the house battery.

Sweet and simple but relies upon you to manually select the appropraite battery all the time.

What is perhaps better is to completely separate the house electrics from the engine circuits. Fit separate isolating switches and an emergency paralleling switch. Feed the engine electrics from one battery and the house electrics from the other.

BUT you will then have to introduce some form of split or divided charging in order to charge both simultaneously.

A VSR (voltage sensitive relay) is the obvious way, a diode splitter is another but really you need the alternator to be battery sensing to counteract the volts drop across diodes.
There are of course other electronic devices that will do the same thing.

IIRC you mentioned Calder's book. That is American, of course, so you find throughout that it will follow the requirements of the ABYC and US Coastguard.

The Americans favour a different approach to the dual battery system. They seem to prefer to use one battery for all purpose but to install the second battery, charged via a VSR, as an emergency battery.

Its the small differences in practices and standards that prompted a couple of us to suggest that you stick to one book rather than trying to mix ideas from different books or with peoples pet preferences which they will push on here.

 

[William_H]

1,2,both.off switches

Well if it were my boat that is the first thing I would remove/ discard. There is this huge temptation to run at all times on both which does charge both batteries and does give the best cranking current by using both batteries but the outcome is that you effectively reduce your system to one battery.
Dual batteries are there to allow domestic services to be used without concern about the engine start battery and to give a redundancy when and if the engine battery dies. If you always start on both you will not know when one battery has died until the other also dies.
IMHO the best system is one battery for engine. His can be a specialist engine start battery (car battery) or a dual purpose leisure battery. It should have a high current isolation switch to allow for disconnection when leaving the boat.
Another battery preferably the deep discharge type is then used for domestic loads. A lower current mast isolation switch is used between the panel and the battery to turn everything off at one switch.
The negatives are commoned together of both systems.
All you need then is a way to connect the 2 battery +ves together for charging only when engine is running. A VSR is best here but you can have a switch if you want. Then you need another switch or the same one top common the batteries for emergency start. Or have a VSR that hyas emergency start built in. Simple fool proof. olewill

 

[Stu Jackson]

The 1/2/Off system is very common and works well but modern thinking is moving away from them to the 3x isolating switchs + VSR layout that others have mentioned. The main reason is that with the 1/2/0ff you need to switch to 'Both' when the engine is running to charge both batteries and then to the house battery when the engine is off to stop you flattening the engine battery. The VSR system does this automatically.

Not necessarily.

It all depends on how it's wired.

There is another school of thought for 1-2-B switches: Keep them, but take your alternator output to the house bank (in the UK the start bank) and use
an ACR, combiner or echo charger to automatically charge the other bank. This means taking the alternator output OFF the C post of the 1-2-B switch, which then makes it only a USE switch rather than a charge and use switch. It is very simple and doesn't require three switches and lets you keep your existing switches.

Here are some links that discuss this in greater detail.

Basic Battery Wiring Diagrams This is a very good basic primer for boat system wiring: http://c34.org/bbs/index.php/topic,6604.0.html [added 9/21/11]

[added 1/31/2012] This is another very good basic primer for boat system wiring: The 1-2-B Switch by Maine Sail (brings together a lot of what this subject is all about)
http://forums.catalina.sailboatowners.com/showthread.php?t=137615

What YOU need to do is figure out what the wiring and switches on your boat actually do as now wired.

 

[ghostlymoron]

What YOU need to do is figure out what the wiring and switches on your boat actually do as now wired.

Agree absolutely. Trace your existing wiring and draw a diagram. This is not easy on a boat and involves crawling into some tight spaces. It helps if you have an assistant so you can waggle one end of a wire and someone can see/feel which one it is on the other side of a bulkhead for example.

You will then be able to determine what each wire/switch does. (and you can put the diagram on this forum and somebody smart will help you)(not me obviously, I'm not smart)

 

[vyv_cox]

Maybe I'm just old fashioned. My boat has had a 1-2-both switch for the past 17 years in my ownership. I never run it on both, i sometimes start on the start battery, charge it for a short time and then switch to domestic. More often I start and leave it on the domestic bank throughout. I have never been unable to start the engine due to flat batteries on this boat, nor on the boats I owned for the previous ten years, which also had the same switches.

It's hardly rocket science and often the simplest methods are the best.