Connecting Driving Lights

[Carslil Jim]

Hi,
What is the best source apart from the battery to pick up the positive to power the driving lights. I was about to install a cable from battery to relay, but wondered if there is another good spot a bit closer to the front (eg starter motor).

I am istalling two by 100W aircraft landing lights, I have two batteries and a 50Amp alternator...I know these are the questions you will have! (and its an 85 V8 County for the really curious).

Regards

Jim.

[JDNSW]

I would take it from the alternator output terminal - after all, this is where the power is going to be coming from, and is closest. Apart from that, the battery terminal on the starter relay - which is the other end of the wire from the alternator, and further away.

John

[Hoges]

Apart from the attraction of their novelty value and/or possibly getting them for "free", landing lights are much less efficient than a decent set of automotive lights and are more prone to damage from constant road vibration ...which is different from the odd "bump" on landing.
I'm presuming they are sealed beam? Their popularity for road use faded some years ago when their shortcomings became most obvious...
But if you get a kick out of making it work good luck to you

[Loubrey]

I've had an old set out of an AT-6 Harvard (450W, 24 Volt) on an old farm runabout SIII and my current set of Lightforce 170 Strikers are easily twice as bright as they were. Couple that with the nearly 100C temperature difference when operating and there is really no comparison...

[BertR]

I've had an old set out of an AT-6 Harvard (450W, 24 Volt) on an old farm runabout SIII and my current set of Lightforce 170 Strikers are easily twice as bright as they were. Couple that with the nearly 100C temperature difference when operating and there is really no comparison...

If you run 24v light on a 12v system they will be dull...and just to add to the confusion on a 12v system 450W would drag 37.5 amps or 18.75 amps on a 24v. It's Ohms law

[steveG]

If you run 24v light on a 12v system they will be dull...and just to add to the confusion on a 12v system 450W would drag 37.5 amps or 18.75 amps on a 24v. It's Ohms law

But isn't a light rated at 450W at 24V only going to run at half the wattage on 12v - hence why its dull?

Steve

[Carslil Jim]

I am picking up the main positive supply from the back of the alternator and that goes directly to the relay, to be switched to the lights.

I suspect I should put a decent fuse between the alternator and the relay?

[Carslil Jim]

The answer is that the supply should be from behind the regulator as the alternator could put out as much as 16V and that may blow the lights.

In the end I picked up 12V supply from a second fuse box I have installed in the bottom of the main console between the seats. It is hooked to the dual batteries with a thumping thick cable.

So for the record, yes a fuse is required and the power must be no more than 12V and 20mp (4mm) wire should be used for the light circuit.

[Loubrey]

If you run 24v light on a 12v system they will be dull...and just to add to the confusion on a 12v system 450W would drag 37.5 amps or 18.75 amps on a 24v. It's Ohms law

Ex-military SIII running on 24 volt, but the lights were still pretty useless and very hot...

Back to Hoges' comment that unless the landing lights are of novelty or sentimental value, you'll do a lot better with modern halogens.

[Wal Rat]

What is the best source apart from the battery to pick up the positive to power the driving lights.

I ran a heavy batt cable to the drivers side inner guard and mounted a 8\eight possition fuse box and used that for all the power to the standard lights and the driving/fog lights also gave me power for the electric fan.
amazing the difference it makes to head lights when they get full voltage