12v timer?

[Aidan Bell]

I have a cool box in the boot of my XC60 which I plug into the 12v supply at the back.
I'm trying to find a 12v equivalent of a mains timer; something that will ensure that I can't accidentally leave the cool box plugged in overnight and flatten the battery. Has anyone ever come across such a thing as a timer for a 12v car supply? Or any product which contains such a timer which I could bastardise?

[Jack_of_all]

could you not set-up a changeover relay.

on the caravan (towbar) wiring loom it only provides a voltage if the engine is running....i.e. the alternator is kicking out over 13.5v. as soon as the votage drops it disconnects the power. I know that this is done via a voltage relay pre-set at a specific level.

ah, just googled this for you... http://www.towsure.com/product/1828-...bination_Relay

[tomto147]

As far as I remember from my previous V50 there was no power in 12v sockets after locking the car.

[Teejay1]

From what I've read of the XC60 only the rear 12v socket is contant live, the middle and front ones power off when you power off the engine.

[Aidan Bell]

Tomto147; that would have an ideal, but I've checked the XC60 and Teejay1's right, unfortunately the 12v socket in the back is the only one that remains on at all times!
Jack_of_all; the relay it looks like the 100% perfect solution, thanks. But I can find no information about how it's fitted. Do you know; is it something that I have to wire into the junction/fuse box, or can I just connect a 12v plug to it and plug it directly into the 12v socket?

[Aidan Bell]

I've found an 12v timer which would do my job well, and is also certainly worth bringing to the attention of other users.
http://www.amazon.co.uk/12-V-Car-clo...9470146&sr=8-1

However, I'm still intrigued by the relay but would be grateful if anyone can offer any more information about it before I purchase. Thank you.

[Jack_of_all]

i'm no expert with the relay option, but would assume that they are just talking it up a little. You can see 2 connctions on one side and 3 on the other.

i would say it requires a feed from the battery (just wire in a ciggy lighter plug for your purposes). and then you will need to work out which 2 of the 3 you would require on the other end....i presume that based on what it is designed for that it includes 2 switched outputs, with one of these having priority...instructions with it will probably explain which is which. you would only want one of these.

make sure you put in fuses. you could make your self a nice bit of kit with a bit of heatshrink or a little box...have you tried maplins?

Towsure have a very good reputation, so would assme its good.

[Aidan Bell]

Many thanks Jack_of_all. My concern was that I didn't want to have to start delving into the bowels of the wiring of the car! But if, as you suggest, it can all be done externally at the socket, then that sounds great. Cheers.
So ... of to Maplins ho!

[wimorrison]

The problem with using the relayy option is that as soon as the engine stops the relayy will drop out which means that your cooller, or whatever is attached, will get no power.

Whatever is fitted needs to be able to monitor the vehicle battery status and disconnect any peripherals when the battery falls to a state that will prevent engine charging.

If someone knows a circuit that will support this I would also like to know of it, unless the one from towsure is adjustable to allow for the situation above?

[Aidan Bell]

Originally Posted by wimorrison

The problem with using the relayy option is that as soon as the engine stops the relayy will drop out which means that your cooller, or whatever is attached, will get no power.

For me that's not a problem at all, that's EXACTLY what I was looking for in the first place, exactly the reason for installing the relay at all