Would i have to use a new relay with these 7 inch headlights. Or is it ok to use stock relay?
Forgot they are H4 60/55 watts. I checked voltage at my headlights not the same has the battery 1v less on right side and 1.8v left side. Maybe there is some corrosion going on somewhere. When I turn on the high beams the left side low beam goes dim and I only get 10.9 v to that low beam connectors i have replaced. I have cleaned the grounds to headlights. Seems i need to check foot switch. Any one have a good place to start. Relay etc
Fuses!
No new relay especially if wattage is roughly equal which it has to be. Some drop is normal, due to wire length. But then the lights further away should see less?
You have a foot switch? On your S3 or the older?
Edit, must of course be the 72. Cool.
The foot switch alternates the connection from battery to either high or low beams. On Series 1 cars, power comes directly from the fascia-mounted switch to the foot switch and on to the lights; there is no relay. There is a lot of voltage drop and relays, supplied through good sized wires directly from battery voltage, will increase voltage at the lights. This makes a big difference in brightness for two reasons. First, the power input goes as voltage squared. Second, increased power increases the temperature of the filament, which shifts its spectrum towards the blue. That means more light and less infrared heat. So the light increases as about the 3rd power of the voltage.
The Hella relay was introduced when stalk-mounted headlight dimmers became fashionable but Jaguar was too cheap to fit a two-position (alternating) switch to functionally replace the foot switch. Instead, the utilized the “flasher” position of the turn signal stalk that was already there. The relay is a kludge. During the day (headlight switch off) it allows the stalk-mounted flasher to retain its original function. When the relay senses that the headlight switch is on (night), it accepts pulses from the flasher and directs them to a latching relay that indexes once for each pulse. It is a mechanical “flip flop.” The beams alternate between high and low each time the flasher is “flashed.” If one holds the flasher lever “on,” the relay coil can overheat. And, given its new function, the flasher switch no longer serves as a flasher at night–there is none.
Because the Hella relay is pricey, and because it’s not a heavy-duty relay appropriately set up to maximize voltage to the lights, its output can be directed to relays just as in the Series 1, with the same benefits. All IMHO as always.
So he should not have the hella?
The hella is horrible. I hate it. I need my flashers at night! Why couldn’t they make it with a push and a pull connection!
I‘m planning to relayize my S3 when I find the time, and hide the fused relays under the fuse box on the fender. During that operation a seperate high beam switch would be appreciated.
Thank you for the information. Another reason to want a perfect S1.
A quick double tap on the stalk will still give you a flash when the headlights are on.
I admit that it is only a personal, emotional barrier. But it is not very graceful or even reliable in my case because one in ten times I miss on the second pull, and repeated flashing is exasperating… in this case for both parties. I like the E-Type arrangement with the convenient dip switch and the flasher on the stalk, no confusion.
Also…
I never drove with the main beams on after not realizing that I had my headlights on… that is my fear 
Thanks david for the information! Yes it’s the 72.
Cheers robert! Good to know that the headlights are powered from headlight switch to foot switch to light. Will have to do some cleaning!