Understanding my boat's wiring (or not)

[Kelpie]

Quick question. I've removed the house battery for charging/storage, whilst the starter battery is still aboard (trickle charged by a solar panel). The other day I went to fire up the plotter to check something, and was surprised to find the system not working, either with the battery switch set to one, two, or both (starter is battery no.2). It had plenty juice in it. Out of curiosity I hooked up the empty positive terminal from the missing house battery, and hey presto everything worked again. The two batteries have a common negative connection.

Is my boat wired properly? Why did nothing happen when I set the switch to '2'?

??

 

[VicS]

I think its impossible to answer without more information about how the boat is wired esp how the battery selector switch is used.

Wired "conventionally" one would expect all systems to have worked if the starter battery ( or even " both" ) had been selected and nothing to have worked if the absent house battery had been selected.

 

[dhippey]

Sounds like the plotter is wired direct to the 'house' battery somehow.

Try putting your battery on to the house battery terminals and turning the battery switch off. Does the plotter still work? If so it is wired the wrong side of the battery switch. However it is not necessarily a fault as it may require an 'always on' feed to keep settings even when the main battery is switched off. This is in the same way as a car stereo needing a feed before the ignition switch to remember its stations.

I'm sure I've not worded this very well, but hope you get my drift.

Regards,
David H.

www.eventoftheyear.co.uk

 

[prv]

Is my boat wired properly?

Define "properly". My boat would do the same as yours (except I don't have a 1-2-both switch at all) and I consider it properly wired - not surprising since I designed the wiring.

One should always understand how the boat is wired though. So you may not need to change anything, but you should investigate so that you understand.

Pete

 

[ghostlymoron]

I'm always astounded that there are so many different ways of wiring a boat considering that all cars are wired the same. For me, 2 batteries, individual isolators and VSR are the way to go. Remember though that some equipment like bilge pumps, Eberspachers and radios may require a constant feed.

 

[VicS]

I'm always astounded that there are so many different ways of wiring a boat considering that all cars are wired the same. For me, 2 batteries, individual isolators and VSR are the way to go. Remember though that some equipment like bilge pumps, Eberspachers and radios may require a constant feed.

Thats no help to the OP

Very few cars have, I suggest, 2 batteries with individual isolators, a VSR, and a constant feed to a bilge pump and an Eberspacher.
Yours must be truly unique.

In the OP's case it is difficult to undersatnd why the plotter did not work when the switch was set to " both", yet worked when the house battery led was "hooked up" ( I assune that meant connected to the starter battery ??)

I think the plotter my be wired to the house battery side of the switch ( ie an always on feed from the house battery)
Therefore
Id check that the switch is operating correctly and is linking both as it should in the "both" position.

 

[Paulka]

I understand, and it is the way my boat is wired, that the "1-2-both" switch is intended to feed the engine starter from either battery 1, or battery 2 (just in case battery 1 is flat/dead) or both.
This is to make sure the engine can be started, even if the "start" battery fails.
Then, the "house" is feed only by battery 2 and has no connection to the"1-2-b" switch.

Just my 2 pennies.

 

[Kelpie]

Thanks for the replies.
Yes, the plotter only worked when I took the +ve house lead and connected that to the starter battery. However it wasn't just the plotter, it was the sounder and VHF as well. As far as I am aware everything worked just fine before I removed the house battery.
Incidentally, the cabin lights will now not work at all. Very odd.
I think I have a problem somewhere...

 

[MoodySabre]

I did something a couple of years that made me think the whole thing had gone awry but in the end there was nothing wrong. Just replace the house battery and you should be back where you started.

 

[VicS]

Thanks for the replies.
Yes, the plotter only worked when I took the +ve house lead and connected that to the starter battery. However it wasn't just the plotter, it was the sounder and VHF as well. As far as I am aware everything worked just fine before I removed the house battery.
Incidentally, the cabin lights will now not work at all. Very odd.
I think I have a problem somewhere...

Goodness knows why the lights now dont work

Definitely sounds as though the VHF, plotter and e/sounder are supplied direct from the house battery and not disconnected when the isolator is off.

BUT BUT If that were the case they should all have worked with the switch in the "both" position. I repeat my suggestion to check the operation of the switch.

It would be very sensible to draw yourself a wiring diagram. As it is at present, before you start incorporating other peoples ideas for "improvements".

 

[prv]

I understand, and it is the way my boat is wired, that the "1-2-both" switch is intended to feed the engine starter from either battery 1, or battery 2 (just in case battery 1 is flat/dead) or both.
This is to make sure the engine can be started, even if the "start" battery fails.
Then, the "house" is feed only by battery 2 and has no connection to the"1-2-b" switch.

If the house panel is connected to the battery, and the battery is connected to the switch, then the house is also connected to the switch. Short of putting a big diode in there, anyway, which would be pretty unusual.

It would be very sensible to draw yourself a wiring diagram. As it is at present, before you start incorporating other peoples ideas for "improvements".

Definitely agree!

Follow with eye / finger all the wires you can get at, using a multimeter on those you can't, to figure out what is connected to what. Then draw a diagram, and if it's still not clear post your diagram here.

Pete

 

[VicS]

if it's still not clear post your diagram here.

 

[halcyon]

I went to fire up the plotter to check something, and was surprised to find the system not working, either with the battery switch set to one, two, or both (starter is battery no.2).

First job set switch to both, check for voltage on service battery terminal, the one that would fit on the battery terminal, you should have a voltage from engine battery.

If you do not check at the selector switch, if no voltage on input 1 you have a faulty switch probably.

Brian

 

[Kelpie]

I think my first port of call will be to put everything back together again (i.e. put both batteries back as they were) and see if it all works as it used to.
The instruments/vhf never used to work with the battery off, and could be operated from either battery.
Worried about the lights though.

 

[MoodySabre]

I think my first port of call will be to put everything back together again (i.e. put both batteries back as they were) and see if it all works as it used to.
The instruments/vhf never used to work with the battery off, and could be operated from either battery.
Worried about the lights though.

My lights not working was one of the issues. In the end there was a dropped earth and hopefully you should get it all back.

 

[nigelmercier]

I hooked up the empty positive terminal from the missing house battery, and hey presto everything worked again...

Sounds to me like you have a diode splitter AND a 1-2-0 switch.

Just don't get me started about diodes again

 

[VicS]

Sounds to me like you have a diode splitter AND a 1-2-0 switch.

Just don't get me started about diodes again

Even if the batteries were charged via diode splitter or a VSR you'd have expected the plotter etc to work either when the starter battery was selected (if they were fed from the "common" terminal) or when "both" was selected (if they were fed from the house battery terminal)

 

[nigelmercier]

Even if the batteries were charged via diode splitter or a VSR you'd have expected the plotter etc to work either when the starter battery was selected ...

I agree, but I meant that to have a splitter and a switch is odd, so perhaps it is all wired in an odd way ...

 

[ianj99]

I understand, and it is the way my boat is wired, that the "1-2-both" switch is intended to feed the engine starter from either battery 1, or battery 2 (just in case battery 1 is flat/dead) or both.
This is to make sure the engine can be started, even if the "start" battery fails.
Then, the "house" is feed only by battery 2 and has no connection to the"1-2-b" switch.

Just my 2 pennies.

yes, that is the answer and is the normal way of wiring a 1-2-both switch.

 

[VicS]

yes, that is the answer and is the normal way of wiring a 1-2-both switch.

Its one one of using a 1-2-both switch and perhaps best used with some form of split charging, be that diodes, vsr or something more sophisticated

Its also possible to feed everything from the switch which then merely selects which battery is the one in service and being charged. Appropriate perhaps when no split charging is involved.