Autostart relay ????

[Guest]

Like many I have a Cool-box on my boat that uses a significant amount of electric to operate it. Therefore I only switch on when engines running ..... can anyone provide a schematic / description / wiring diagram of a circuit to automatically switch on when engine's running, switch off when engine stops ......

Then I can get maximum time from the box without having to remember to do it manually .....

My email : nigel.luther@qualityservice.com

Thanks
Nigel

 

[Guest]

Nigel,, ever thought of wiring directly out of your ignition switch?
regards
peter

 

[Guest]

Here is the device you are looking for.

Go to

http://www.yandina.com/hints.htm#Frig

 

[andyball]

You could use a relay switched by the charging lamp circuit(if you have one,and assuming it's a "normal" alternator)....so it's only on when the battery is charging.

I use this on my van, to charge the second battery,only after the main one is charged.

But....why not from the ign. switch?....is it diesel, with a separate stop switch?

 

[Guest]

Nigel

I'd go for the "ignition switch" for simplicity.

My motor has a loud alarm that sounds when the ignition is "ON" and the engine isn't running.

It's irritating but it makes it impossible (it's that loud!) to leave the power on when the engine is stopped!

I think that taking the power from the ignition switch and fitting an alarm where the ignition light is would probably be an economical and foolproof solution.

I wouldn't advise just using a light (even the ignition light) as the last time I had to jump start my van was on a sunny but misty day when I left the lights on.

Best regards )

Ian D

 

[Guest]

To all responders ....

To all - Ia have a diesel engine that has manual fuel cut off for stopping like most. The 'ignition' circuit is basic to say the least and I wish to make sure that my batterys do not get 'sucked dry' by the cool box. I have forgotten too many times to 'pull the plug' on the box and ended up with no battery capable of starting the engine !
I have had a suggestion of the Caravan shop fridge relay, which is actually a very good idea .... plus have considered the wiring into the accesories side of the 'ignition switch' .....

I was looking for the bright spark who could give me the easy answer to an 'auto system' !!!!!

Anyway, thanks and lets see what works best and is within my limited capability - electically !!!!

Cheers

 

[philip_stevens]

Re: To all responders ....

Nigel,
I have two batteries in the general circuit on my Konsort. Usually only one battery is on-line at one time. If I should start my engine, only one of them WOULD HAVE been charged. I say would have, as I fitted two auto relays - one to each battery - and wired the operating supply from the ignition switch. This was advised by one of the professionals at the Soton boat show. (I think it may have been on the Adverc stand, but don't quote me on that). Anyway, when the engine is started, and not before as with wiring it from the ignition switch, the relays only close when the alternator is charging. In this way, you won't put any other accessory onto the batteries before the engine is started.

If you wire your fridge in this way, i.e. from a relay operated by the ignition switch, it will only close once the engine has been started and the alternator is charging. Once you stop the engine, the relay drops out and the supply to your fridge is disconnected. If you should want to run the fridge when on shore power, install a bypass switch to feed the output side of the relay i.e. the side that is connected to the fridge. In this way, you will get auto cooling when the engine is running, and a supply if connected to shore power.

I hope this is clear to you. If not, I can send you a diagram.

regards,
Philip

regards,
Philip

 

[andyball]

Long response(sorry)

It can't just be a simple relay operated by the ign. switch....or it would energise as soon as the key was turned to the relevant position.....some switches have an "accessories" position, which is disconnected when starting, but this doesn't solve the problem of having to switch off the coolbox when the engine has been stopped by the fuel cut-off.

A "split-charge" or "fridge" relay kit is often just a cheap relay with some expensive instructions on how to connect it to achieve the aim of "automatically" switching off the load when the engine is stopped.

My previous post mentioned how I achieved this on my van: with some types of alternator( ie most car ones),all you need is a 'normally closed" or "changeover" relay, the coil on this is connected to a switched 12V supply one side, to the field coil connection (and charge warning lamp) on the other....The Df terminal.... usually!

When the switch is on, but engine not running: there is power to the relay via the switch, but the relay is energised because it earths through the field coil( just like the warning lamp does), so because it's a normally closed relay, it's open! and the fridge doesn't work.....!

Once the engine starts....the charging lamp (and our 'magic' relay) are no longer earthed, so the lamp goes out and the relay is "off"..... ie closed (it's a normally closed or changeover type......)hence the fridge is ON.

If the engine stops, the charge warning lamp and relay will be on again, and the fridge will be off.

The supply is switched via the ignition switch, so that the normally closed relay does not operate the fridge when the engine AND the ignition are off.

Without a charge warning lamp system.....or indeed with any type of Dynamo! things get more complicated: I have used a car alternator voltage regulator connected so as to switch on the load when the main battery voltage exceeds 14.4V ( the "ususal" switching voltage for car regulators)......however, with large battery banks and small alternators/dynamos, many installations would take some time or high rev's to achieve this voltage,( if ever), during which time the fridge would be OFF.

A zener diode could be used to switch the load on at a lower voltage, but since even the above looks complex when written down, I'll stop there.

I used my van as a motorcycle electrician, and wanted a large extra battery for starting bikes/cars....that even if it was flattened totally, would not affect starting. The commercial "split -charge" relays I saw, did not actually achieve this, hence the above.

 

[Strathglass]

Re: Autostart relay another way????

There is a failsafe way. This involves the use of two items, a single pole normally open relay and a momentry action push to make switch.
A wire from the ignition on supply is taken through the relay contacts to the relay coil, the other side of the relay coil is taken to zero volts. The momentery action switch is connected across the relay contacts. The power to your cool box comes from the junction of the relay coil and the contact.
This will not interfere with your normal starting, once the engine is running press the switch and power will go to the coolbox. when the engine is switched off power will be removed from the coolbox and will not return without pressing the switch.

 

[Guest]

The engine oil pressure switch is an easy way to detect if the engine is running or stopped. A relay in circuit with the cool box but, I am sure you can work the rest out.
Cheers

John Dillon

 

[colinroybarrett]

Do you have a squirkit diagram?

Andy,

If you’ve an electronic copy of the circuit that isn’t copyright! (re: Zener diode version) I’d very much appreciate a look?

Cheers,
CRB
Kahawi@hotmail.com

 

[Peter_the_Grate]

Nigel,
Not sure how much current you're talking about, but since you call it a coolbox and not a refridgerator, it might be like mine and thermoelectric. I have a little device in series with the coolbox, which cuts off the power when the voltage drops to 11.6 volts and cuts in above 12.8 volts. It leaves enough power to start the engine if I forget to switch the coolbox off and also restarts the coolbox if I forget to turn it on (when I restart the engine). Be aware that it has a maximum current rating of 5 amps. I obtained it from Towsure (http://www.towsure.co.uk) and it cost £7.95.

Regards.

 

[andyball]

Re: Do you have a squirkit diagram?

Sorry, I don't have a scanner....but for the money/effort....I'd buy one of the towsure gadgets (see post by Peter Aird), and if 5amps wasn't enough, use it to energise a relay.

Having said that....11.6V with only a coolbox on load seems a bit low....especially if batteries are borderline and are starting a diesel!.

The oil pressure switch dodge is a good one if you have one!