Wiring advice needed.

[qwerty]

As mentioned in my progress thread I am isntalling somr auxillary guages, water temp and oil pressure.

I have a place to put them and I've ran the signal wiring.

The next part is providing them with power and also moving the cigarette lighter to a different location as my new guage holder covers where it used to go.

So I have the +ve and -ve wires from the cigarette lighter, will I be ok to run all three from those? Or will it draw to much current? What is the ideal solution?
I would rather do it right and not have the car set on fire.

Thanks in advance for help.


Tom

[greebo12]

I would have thought powering two gauges would draw less current than the Ciggy lighter.

[qwerty]

Nov 3, 2017 12:38:11 GMT greebo12 said:

I would have thought powering two gauges would draw less current than the Ciggy lighter.

I'm more worried about the additional draw say when I have the Sat Nav or my phone plugged in.

[steveo3002]

id guess it will be okay , if you want to check the makers website or instructions I'm sure it would tell you the current draw, then add that to the phone charger and compare to the fuse rating

[squonk]

Many cigarette lighters are fed by a permanent live feed. If yours has the guages will never shut off and it will flatten the battery if the car is left for a couple of days or more.

[qwerty]

Nov 3, 2017 22:19:39 GMT squonk said:

Many cigarette lighters are fed by a permanent live feed. If yours has the guages will never shut off and it will flatten the battery if the car is left for a couple of days or more.

Good point. Something I will definitely check!

[fad]

Nov 3, 2017 22:19:39 GMT squonk said:

Many cigarette lighters are fed by a permanent live feed. If yours has the guages will never shut off and it will flatten the battery if the car is left for a couple of days or more.

This. If it isn't a permanent live, then make sure your cable to your gauges is of a higher rating that the fuse feeding that circuit (your fuse must always be the weakest link without exception regardless of the current something on the circuit is expected to draw).

[Dorset_Clive]

Cig lighters are pretty high current, typically 10-20A,after all it is effectively just a heating element between +12v and gnd! Certainly much more than gauges and a sat nav would draw.

As for being permanently live, I'd be surprised on an older car. Moderns, with battery level sensing electronics can shut off the power if the battery gets too low, but on a (say pre-2010) car they wouldnt normally have a permanently live cig lighter skt for the worry of flattening the battery. Of course, very easy to check if you've got a phone charger with an led.

[squonk]

Nov 6, 2017 18:53:55 GMT Dorset_Clive said:

As for being permanently live, I'd be surprised on an older car. Moderns, with battery level sensing electronics can shut off the power if the battery gets too low, but on a (say pre-2010) car they wouldnt normally have a permanently live cig lighter skt for the worry of flattening the battery. Of course, very easy to check if you've got a phone charger with an led.

As an ex car radio installer from the eighties, from experience I can tell you that it is probably more likely to be a permanent live in an older car. In the days before digital stereos were standard fitment and there was no memory feed in the radio loom it was commonplace to piggy bag a feed from the fag lighter because it was normally a permanent live. It cost less to the manufacturer to make it permanent rather than including a relay to isolate it with ignition. The exception was usually Japanese cars.

[Dorset_Clive]

Nov 6, 2017 22:03:14 GMT squonk said:

As an ex car radio installer from the eighties, from experience I can tell you that it is probably more likely to be a permanent live in an older car. In the days before digital stereos were standard fitment and there was no memory feed in the radio loom it was commonplace to piggy bag a feed from the fag lighter because it was normally a permanent live. It cost less to the manufacturer to make it permanent rather than including a relay to isolate it with ignition. The exception was usually Japanese cars.

Well there you go, every day a school day! I was basing on the 80's and 90's cars I've rallied and always needed the ignition on to power the map magnifier which was plugged in to the cig lighter skt.

[qwerty]

Well the car in question is an early 90s VW, I've yet to make any progress as I've been stuck on DIY duty in the house.


Tom