Noob question...

So this is likely a super stupid question, but I'm a long way down the home mechanic learning curve...picked up my lovely '03 110 SW last week and am looking at a couple of electrical additions...one being an extra cig lighter socket in the back (for camping fridge) and the other being wiring in a Skytag...

So the silly question is...do I need to disconnect the battery before splicing into any existing wiring? The sensible part of my brain says 'of course', but having never done any electrical work on a car I'm not sure...

Thx...

Hi,

Yes , would be the correct answer.

Also , before you do, make sure you have the radio code, if needed.

Do not forget fuses.

But TBH, knowing how car electrics, although being simple in theory do seem to cause all manner of problems, I would suggest finding a mate who knows their car electrics and bribe them with a bacon butty, tea , cake, to come and at least oversee what you are doing, Just to help stop a silly mistake happening.

Cheers

I don't know what engine is in a 2003 being an old school kinda guy but...if you disconnect Willy nilly you may upset ecu, alarm and lose radio codes.
Once you have the info then yes, always disconnect the battery.

Bugger, too slow again..

Another little point is, without wanting to seem patronising.

Do you understand , Amps, Watts, Volts? You mention a camping fridge, I am not sure what wattage they are, but you could end up with a serious issue if you overload the electrics.

Cheers

neilly said:

Another little point is, without wanting to seem patronising.

Do you understand , Amps, Watts, Volts? You mention a camping fridge, I am not sure what wattage they are, but you could end up with a serious issue if you overload the electrics.

Cheers

Click to expand...

Not an expert by any means so all advice welcome...the fridge is set-up to run off a 12v supply and I've run it through the cig lighter on another vehicle, jsut want to avoid running the cable from the front when using it.

Not sure I've got any mates that I'd trust to advise on car electrics, so may have to outsource to a pro and take the cost hit...

Thanks

Hi Again,

Not sure if this will be beneficial, But @cowasaki did a very good write up for car electrics.

https://www.landyzone.co.uk/land-rover/tutorial-car-electrics.245168/#post-2880214

Unfortunately , it appears the pictures have disappeared over time.

Cheers

I'm no leccy pro either but the fridge will have a label on it telling you it's requirements. Post the details up and someone will tell you the cable / fuse/connection sizes etc.
Then just use common sense for the cable routing to avoid it getting damaged. I run all my exposed cables from front to back on top of the chassis inside flexible conduit.

Just to add a bit more detail, you need to know the wattage of the fridge. Failing this, you may see a fuse amperage rating. For example, some cool boxes are rated at 10amps, so you need to make sure that any wiring would be rated to 20amps (to allow a margin of safety). For a 10amp load, I'd fit a 15amp fuse. Too thin a wire will heat up and may even go on fire before you blow a fuse.

If you are connecting straight to the battery as I have with my fridge then there is no need to disconnect the rest of the car IMO. Just make sure you connect the positive up last and that you have a fuse near the battery end. Those nifty fuse boxes on ebay that light up when the fuse has gone are pretty good.

If you are doing anything with the car electrics themselves then obv disconnect the battery.

The 2003 TD5 should be perfectly happy when you disconnect the battery and reconnect it. Usually nothing needs resetting or unlocking afterwards in my experience.
As people are suggesting above, fridges tend to be quite current hungry (after all, you're running a compressor to drive the refrigerant round a circuit) so ensuring that you have a sufficiently hefty wire and fuse will help avoid problems later. It can be very tempting to just splice new accessories in to a handy live wire, but try and resist this. There's not a lot of room in the TD5 fuseboxes to fit additional wires and fuses, so in mine I've run another (fused) live wire from the battery box to an extra fuse box and this is what powers my various accessories. Dashcam, tracker, sockets, inverter and so on. It sounds complicated, but it's worth doing because then you've got something to wire additional accessories in to in future.

Depending on what you are doing, you don't need to disconnect the battery. Just be careful and mindful to not short something out. You'll probably want power to test things before finalising them anyhow. And at the end of the day you don't have to have the wiring you are installing connected while you install it.

I know this doesn't tally with some of the replies above. It really comes down to your comfort level, knowledge and experience and to a larger degree how sensible you can be.

But as a for instance, if you need to change a house bulb, do you turn all the electric off in the house, or just make sure the switch for the bulb you are changing is off?