Where's the damn off switch?

RIN

RIN

Well-Known Member
Joined
2 Mar 2003
Messages
3,236
Location
West Midlands
Visit site
I have just fitted a Nasa Clipper log to the boat and after hooking up the leccy, the unit came on. Good I thought but when I tried to switch it off, there was no power switch! This was disappointing as I never saw a mention of the fact it did not have an on/off switch when researching the purchase. Now I am sure on more modern boats there is a separate 12v circuit for instruments, but not on ours. All the instruments at the helm have a power on/off button.

So two things

where can I get a small waterproof switch that will fit at the helm. Must be low profile and not a toggle switch as I will certainly snag that at the helm. I have looked at Maplin etc but cannot find one.

Alternatively, I am told you can purchase a (Volvo?) Relay that will engage when the ignition is switched on. This means breaking into the wiring loom though. Has anyone done this before?

Any advice gratefully received
 
Richard

There are several different ways of doing this. Here are a couple of them.

Take a supply off terminal 15a on the ignition switch, power will be only on when the ignition is on.

or

Take a supply from the instument panel light switch, if you go on the red/blue power will be on with the ignition on. This basically comes from the iginition switch pin 15b. If you go on the output side of the lamp switch (red cable) you could switch on or off but you would also have the instument lights on/off at the same time. Of course the ignition will be on as well.

The choice really is up to you - what do you have on your hoover?? Sorry couldn't resist that!
 
carlton said:
You're right. From your link, Part # 711439 looks as though it'd do the trick. (£5.63).
Click to expand...

Thanks all, even Peanuts! Yes that could work. I'll have to call them to get the dimensions as it will be a tight fit.

I'm still interested in hearing from anyone who has installed a relay on the ignition circuit though
 
RIN said:
Thanks all, even Peanuts! Yes that could work. I'll have to call them to get the dimensions as it will be a tight fit.

I'm still interested in hearing from anyone who has installed a relay on the ignition circuit though
Click to expand...

Unless i'm missing something here, a relay is totally pointless. A relay is, in essence, an electric switch. You turn on the ignition, the relay activates and sends a positive supply to the log. If you take a wire from the ignition switch directly as described, to the log, it does exactly the same thing.
 
PaulGooch said:
Unless i'm missing something here, a relay is totally pointless. A relay is, in essence, an electric switch. You turn on the ignition, the relay activates and sends a positive supply to the log. If you take a wire from the ignition switch directly as described, to the log, it does exactly the same thing.
Click to expand...

The idea of the relay is that you are not going to be powering the log from the ignition circuit as you will only be switching it and it can be fed from its own suitably fused supply and eliminates the risk of overloading the ignition circuit.
On the current volvo engines there is this facility built in to the ignition circuit, you just add the circuit you wish to switch to the switched contacts of the relay
 
aquapower said:
The idea of the relay is that you are not going to be powering the log from the ignition circuit as you will only be switching it and it can be fed from its own suitably fused supply and eliminates the risk of overloading the ignition circuit.
On the current volvo engines there is this facility built in to the ignition circuit, you just add the circuit you wish to switch to the switched contacts of the relay
Click to expand...

Hmm, but in the case of the log, that uses minimal power i still don't think the relay is needed. An inline fuse is easily added and the log wouldn't overload the circuit. If you wanted to power something that needed more power, then yes the relay would be needed.

If the OP still wanted to fit a relay, it's pretty simple and no need to pay Volvo prices. No need to hack into the loom either. A standard automotive relay would suffice, providing it doesn't need to be waterproof. Pretty much any car in the local scrapyard will have at least one or two relays that will do the job just fine.

There are four terminals on the relay :

Positive supply (from where ever the log is being powered from currently, fused)
Positive output to the log
Negative
Switched positive, from the ignition switch if you only want it on when the ignition is on
 
gimmesunshine said:
avoid the relay, if your not overloading the circuit then you adding something which is more likely to go wrong... keep it simple
Click to expand...

relays are reliable, just about any engine will be relying on relays to keep running, you are more likely to cause a problem by not fitting one, its not good practice to just keep adding to circuits, after all you want reliability when at sea and no you dont need to pay volvo prices you can easily get one from your local auto electrical dealer that will be equally as good.
 
aquapower said:
relays are reliable, just about any engine will be relying on relays to keep running, you are more likely to cause a problem by not fitting one, its not good practice to just keep adding to circuits, after all you want reliability when at sea and no you dont need to pay volvo prices you can easily get one from your local auto electrical dealer that will be equally as good.
Click to expand...
That is really why I was interested in hearing from anyone who has installed a relay. It would seem an improvement to the electrical infrastructure of the boat and capable of providing more options for future upgrades rather than a quick fix. I still think it means cutting into the loom though.
 
RIN said:
That is really why I was interested in hearing from anyone who has installed a relay. It would seem an improvement to the electrical infrastructure of the boat and capable of providing more options for future upgrades rather than a quick fix. I still think it means cutting into the loom though.
Click to expand...

It does not mean cutting into the loom. I already explained the wiring for a relay. I still think it's NOT the way to go, it IS something else to go wrong and how many more "future options" would you consider tagging onto the relay ?

If you want future options and separate circuits, why not add an addition fuse board ? Take a supply from one fuse to a switch for the log and leave the other fuses for possible additions in the future.

Where are you powering the log from at the moment ?
 
PaulGooch said:
It does not mean cutting into the loom. I already explained the wiring for a relay. I still think it's NOT the way to go, it IS something else to go wrong and how many more "future options" would you consider tagging onto the relay ?

If you want future options and separate circuits, why not add an addition fuse board ? Take a supply from one fuse to a switch for the log and leave the other fuses for possible additions in the future.

Where are you powering the log from at the moment ?
Click to expand...

I'm powering it from the original feed to the previous log, which comes from a 12v busbar under the helm, then through a fuse. The wiring looks as if it has been done by someone fond of spaghetti

A new 12v fuseboard is a good idea. It could go on the main board in the cabin if I can find room, It already houses the leccy meters, 12v and 240v panels and radio

I have had a look at the KAD32 wiring diagram and I think the wire from the ignition switch is the red/blue one - can't work out if it is 15a though. I also thought the loom fits in to the ignition switch by a connector rather than directly wired on to a terminal that can be opened, hence my view that i needed to cut that wire to get it to also power a relay. I could well be wrong on that from what you are saying so will check when I get down to the boat next
 
RIN said:
I'm powering it from the original feed to the previous log, which comes from a 12v busbar under the helm, then through a fuse. The wiring looks as if it has been done by someone fond of spaghetti

A new 12v fuseboard is a good idea. It could go on the main board in the cabin if I can find room, It already houses the leccy meters, 12v and 240v panels and radio

I have had a look at the KAD32 wiring diagram and I think the wire from the ignition switch is the red/blue one - can't work out if it is 15a though. I also thought the loom fits in to the ignition switch by a connector rather than directly wired on to a terminal that can be opened, hence my view that i needed to cut that wire to get it to also power a relay. I could well be wrong on that from what you are saying so will check when I get down to the boat next
Click to expand...

I had added a couple of new items over the last few months and had "piggy backed" them from other fuses. I've just added a couple of addition items and decided i was in danger of making the wiring a mess, bit like the spaghetti lol. I fitted a new, 6 way fuse holder and wired everything neatly to that. Looks very neat and gives me a couple of spare fuses for the future.

If the wiring fits the back of the ignition switch with a plug, then you're right that you'll have to cut into a wire, or join to it. Rather than cut it though, i'd bare some insulation and solder a wire to it, then tape securely. Still rather go with the new fuse board and not a relay though :)
 
The 2 cables coming off the ignition switch are from 15b and are red/blue, one going to the alarm unit and the other is the positive supply for the instruments.

For your supply without cutting into the loom I would either piggy back either off the in coming cable on the instrument light switch or on the positive pin on the RPM gauge, I know you have already stated you have an in line fuse on the instrument cable.
 
You can energise the relay from the blue/red wire and as already said its best to use a piggy back terminal, avoid scotch loc connectors on a boat, its not good practice to add other circuits to ign circuit without a relay, for a start its not advisable to run a delicate electronic item from a start battery as the surge when you start can destroy it, thats one of the reasons for the relay.
There are many engine electrical faults caused by adding to circuits that should be left as are.
 
You must log in or register to reply here.

Share this page

Top