Hi all, just out of curiosity, does anyone know what the maximum wattage, that could be put through to the H1 bulb, without creamating the wiring? Or does anyone know the ampage rating for the wire? Many thanks Richard 

Forgot to mention, car is ford focus 2008 zetec mk2, da3 1.8 petrol estate with duratec he.

The wiring can handle up to 7 Amps continuously, per headlight.

Standard H1 halogen lamp = 55W

Assuming a vehicle voltage of ~ 13V with the engine running then the current will be around 4.25A per headlight

Many thanks Unofix.

 

So in theory, at 13v at 7amps you could get away with a 90w h1 bulb.

 

I don't know what alternator is fitted to your model but a pair of bulbs consuming 180Watts will almost certainly exceed it's output and that's ignoring the consumption of the other lighting.

I used to have a Ford Cortina MK5 with 2 rally daylighters with 150w each and it coped!

I'll try it out to see what happens. See if battery light comes on and look at voltages!

46 minutes ago, RichyB said:

I used to have a Ford Cortina MK5 with 2 rally daylighters with 150w each and it coped

That was in the days before "smart" charging.

Still, at least your car won't have a BMS.

22 hours ago, RichyB said:

I used to have a Ford Cortina MK5 with 2 rally daylighters with 150w each and it coped!

Yes the Cortina would have been fitted with the Lucas ACR17 alternator rated at 36A or depending on the spec you may even have had a Lucas ACR18 rated at 45A 👍

The alternator on your 2008 Focus will be fine. Two lights of a combined load of 180W is nothing like the load imposed by heated seats or heated screens.