Battery switches - 4-way vs key-type

Thanks again for all the replies - it really is much appreciated.

I've spent some more time studying the current system and I think I now understand what's going where.

There are two batteries (95Ah and 105Ah) which are alternated and selected via the 1,2, both, off switch. The output from the switch goes directly to the key isolator and the output from that goes to the engine (presumably splitting to go to both the alternator and the starter motor), a fuse box which some navigation instruments used to be connected to, and the CB switch panel.

What I intend to do is as follows:

1. Add a third dedicated cranking battery which is wired directly to the starter motor.
2. Wire the alternator to the house bank (therefore, I understand, avoiding the possibility of damage should the 'Off' position be selected accidentally whilst the engine is running).
3. Replace the existing combined key isolator/CB switch panel with a new CB switch panel, doing away with the key isolator in the process.

Does that all sound reasonable please?

I'm considering a Blue Sea 12 pos panel - the price is a bit scary, but their quality seems highly rated. How many switches do other people here have? I have very simple requirements, and yet I seem to be struggling to keep the number of switches down! I have nav lights (deck, tri and steaming obviously), a deck light, compass light, cabin lights, 12v sockets, VHF, chart plotter, navtex and Tackticks (2 power sources required). No electric pumps, heaters or fridge, and DC only.

I've now purchased my solar panels (a BJ bargain, hopefully!!!! :D) and I have a Steca Solarix Gamma controller. I want to connect this to the house bank, but I'm not sure exactly what this involves? It has battery, solar panel and load connections.

Also, what's considered the best method for connecting 3 flexible panels together without reducing their flexibility positioning-wise? Pity they aren't wireless!!! :rolleyes:

Thanks!
 
Oh, and thanks for all the comments regarding VSRs. I can definitely see the benefits of these, but at the moment I think I want to stay with the 1,2, both, off switch. My intention is to use is just as vyv_cox suggested, essentially only changing it to 1 temporarily for engine starting and charging, and then moving it back to 2 for the house bank and leaving it there.
 
Id suggest you post a diagram showing how you propose connecting, switching and charging the batteries.
I'm not sure I follow your written description. A diagram will be easier to follow.


Re the solar panels it my be easier to wire each one back to the regulator separately. Or to a common junction box and then from there to the regulator. It'll depend on their positions relative to each other.
I think you are heading to a set up in which a VSR is the obvious way of directing the charge between two banks.

Don't forget it will be necessary to determine what cable size will be necessary between panels and regulator and between regulator and battery to avoid excessive voltage drop.

Google will find instructions for installing the regulator if you do not have them. There may be a correct sequence for connecting it,
The "load" connection is for a load which will normally be left running but which you would want to disconnect at some preset voltage to avoid running the battery completely flat. A fridge perhaps.. although they sometimes have their own automatic low voltage disconnect feature.
 
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syvictoria said:
Oh, and thanks for all the comments regarding VSRs. I can definitely see the benefits of these, but at the moment I think I want to stay with the 1,2, both, off switch. My intention is to use is just as vyv_cox suggested, essentially only changing it to 1 temporarily for engine starting and charging, and then moving it back to 2 for the house bank and leaving it there.
Click to expand...
It's easy to forget to change over and end up with a flat battery.
 
Okay, I've finally got a decent internet connection sorted out at home and so I can now post outside of library opening hours!

I've drawn a plan. It's essentially a rip off of one of Nigel Calder's - thank you Nigel! - but with my additional battery added. I still need to add the solar panels to the diagram. The house batteries will be Trojan T105s, and I'm considering a RedFlash cranking battery as space is tight.

I've now purchased a couple of small Blue Sea CB panels (as they were cheaper than the one I'd previously been considering!). I'm thinking about putting my VHF, plotter/GPS (CP180), and two Tacktick boxes on one switch, and connecting them together pre-switch via a Blue Sea fuse box, simply because I already have the fuse box (the type with blade fuses). However, is it a bad idea to mix fuses and CBs, or is it possible to over-fuse the circuit?

Thank you!
 
Your wiring of the house batteries together is wrong unless you wanted 24V.
They need to be in parallel, not series for 12V.

You're using the 1,2,Both,Off switch to decide which battery bank supplies the domestics.
With that diagram the starter is always using the starter battery and in addition may use the house batteries. Never just the house batteries by themselves.

The alternator will do not nothing (except possibly blow if the engine is running) when switch is moved to position 1.

Start of soln is to:
All negatives of cranking and house batteries should be connected together.
Starter Motor should be on output side of 1,2,Both,Off switch where House Loads is currently shown.
House loads needs to be connected to House Batteries positive preferably via breaker switch.
Alternator should be connected to:
1. Cranking Battery with VSR to then supply charge to House batteries.
or
2. to diode splitter with two outputs. One out to cranking, other to house.

Note: Engines are usually prefitted with wire from alternator to starter motor positive. This needs disconnecting if using option 1 or 2 above.
 
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Thanks Talulah.

Sorry, the house batteries are 6v, and so I think that makes my wiring right?

And I quote from NCs book:

"If the alternator is wired to the house battery, the cranking battery can only be charged by placing the switch in the BOTH position, but there is no risk of open-circuiting the alternator."

It was the 'no risk' bit that made me pick this layout, but perhaps I'm misunderstanding something?
 
syvictoria said:
Thanks Talulah.

Sorry, the house batteries are 6v, and so I think that makes my wiring right?

And I quote from NCs book:

"If the alternator is wired to the house battery, the cranking battery can only be charged by placing the switch in the BOTH position, but there is no risk of open-circuiting the alternator."

It was the 'no risk' bit that made me pick this layout, but perhaps I'm misunderstanding something?
Click to expand...

No. You're right.
The reason I'm not keen on the setup is because the priority is on the domestic batteries which for me doesn't feel right. But it will work.

It does raise other issues though.
The alternator sense voltage is likely to be coming off the cranking battery.
If the 'Cranking' battery is fully charged the alternator won't throw much out. You could end up with a depleted domestic batteries that takes forever to charge and you'll be wondering why they aren't getting charged by the alternator.
 
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syvictoria said:
I seem to be struggling to keep the number of switches down! I have nav lights (deck, tri and steaming obviously), a deck light, compass light, cabin lights, 12v sockets, VHF, chart plotter, navtex and Tackticks (2 power sources required).
Click to expand...

While it is nice to have everything on different switches you can of course combine multiple things off the same switch. The downside is that if one thing blows the fuse then everything else on that switch also goes down.

So, for example why not wire your compass and instrument lights to the tri light? It is also common to wire VHF without a switch (use an inline fuse) VHFs can be turned off and if in emergency its one less thing to turn on to use it.

Whilst not necessarily ideal, my boat has 4 switches:
Steaming light,
Night sailing lights,
Nav instruments,
Domestic (incl cabin lights).
 
dedwards said:
So, for example why not wire your compass and instrument lights to the tri light?
Click to expand...

Assuming by tri light you mean the tricolour at the top of the mast then this is only applicable when sailing.
Hence you could wire compass light and instrument lights together but not to the tricolour. Otherwise what would you do for illumination when motoring?
 
syvictoria said:
Okay, I've finally got a decent internet connection sorted out at home and so I can now post outside of library opening hours!

I've drawn a plan. It's essentially a rip off of one of Nigel Calder's - thank you Nigel! - but with my additional battery added. I still need to add the solar panels to the diagram. The house batteries will be Trojan T105s, and I'm considering a RedFlash cranking battery as space is tight.

I've now purchased a couple of small Blue Sea CB panels (as they were cheaper than the one I'd previously been considering!). I'm thinking about putting my VHF, plotter/GPS (CP180), and two Tacktick boxes on one switch, and connecting them together pre-switch via a Blue Sea fuse box, simply because I already have the fuse box (the type with blade fuses). However, is it a bad idea to mix fuses and CBs, or is it possible to over-fuse the circuit?

Thank you!
Click to expand...

IMHO thats pretty useless with no way of charging the starter battery other than by setting the 1, 2, B switch to Both. Does Calder not suggest a VSR?

There is no way of starting from the house battery other than with the 12B switch in both... and that could be pretty useless if the starter battery is totally defunct


However Tallulah is wrong in suggesting that the alternator might blow if the switch is moved to position 1. While it is is permanently connected to a battery bank there is no problem.

IF the alternator is battery sensed then the sensing must always be from a battery that is being charged, but I assume it is machine sensed.

IMHO a 1,2, B switch is quite inappropriate I would use separate isolators and an emergency linking switch.

See attachment for what I am suggesting. A fuse in the supply to the house services switch board would be a good idea. Maybe also a Mega fuse in the supply to the starter motor.
 
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VicS said:
IMHO thats pretty useless with no way of charging the starter battery other than by setting the 1, 2, B switch to Both. Does Calder not suggest a VSR?

There is no way of starting from the house battery other than with the 12B switch in both... and that could be pretty useless if the starter battery is totally defunct


However Tallulah is wrong in suggesting that the alternator might blow if the switch is moved to position 1. While it is is permanently connected to a battery bank there is no problem.

IF the alternator is battery sensed then the sensing must always be from a battery that is being charged, but I assume it is machine sensed.

IMHO a 1,2, B switch is quite inappropriate I would use separate isolators and an emergency linking switch.

See attachment for what I am suggesting. A fuse in the supply to the house services switch board would be a good idea. Maybe also a Mega fuse in the supply to the starter motor.
Click to expand...

Yes, Nigel Calder does talk about VSRs later on, but my diagram is taken from a 'solution' he gives prior to this in the book (3rd ed. p38 to be precise).

Unfortunately, with 6v deep cycle Trojans, I don't think that I'm going to be able to start from my house bank anyway? (and this is something that's concerned me previously - does anyone know whether a Beta 25 can be hand cranked?)

My alternator will be a 70amp upgrade on a Beta 25hp, if that's of any relevance.

I really can see the virtues of a VSR, but it does also add an additional layer of complexity and power requirements to my system. I will have to read up on VSRs again...

Thanks all.
 
I really can see the virtues of a VSR, but it does also add an additional layer of complexity and power requirements to my system. I will have to read up on VSRs again...
Click to expand...

The virtue of a VSR is that it allows two battery banks to be charged simultaneously.

Not without some snags of course basically because it does so by connecting the banks together once the volts on the bank with priority have risen to a certain value ( typically 13.7)
Care is need if the boat has high current equipment, such as an electric anchor winch, to either design the circuit so that this load wont be supplied via the VSR or by using a suitably rated VSR and wiring.

The obvious alternative is a diode splitter. Their drawback is the voltage drop across them. This results in batteries not so fully charged as they would other wise be. Depending on your point of view this either does not matter or can be overcome by battery sensing for the alternator. But for the volts drop diodes are the better choice IMHO although there could still be charging problems if one of the batteries becomes totally defunct.
 
VicS said:
Care is need if the boat has high current equipment, such as an electric anchor winch, to either design the circuit so that this load wont be supplied via the VSR or by using a suitably rated VSR and wiring.

.
Click to expand...

You can get VSR's that sense engine starting, or bow thruster or winch operation, and drop out the VSR.

Brian
 
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