Headlight relays Volvo P1800

[CLIVERALLY]

Just a quick one..are there any benefits in terms of power to the bulbs by fitting relays to low and high beam circuits ? I understand the theory of voltage drop.
If anyone has introduced the relays for their P1800 I would be interested to know the detail and benefits

[tdz840]

Hi
To reduce the effects of voltage drop the relays need to be as close to the lights as possible with a low resitance power feed either direct from the battery or a +12V distribution point.
That means in the nose or as close to that as possible. Ive fitted relays for the spots, HLs and horns and located them in a row next to the nearside wing/radiator.
Worked well for ten years
Russ

[CLIVERALLY]

Thanks Russ.
Iam going to fit them for the Headlights.
Did you fit separate ones for Main and Dip ?

[Derek UK]

Measure the voltage drop first and then properly clean ALL of the connections in the system up to the bulbs and then recheck. You might find you go from a bit over 10v up to 11.5 volts and that will make a big difference. It will also cost you nothing. Halogen lamps will benefit most as they really need to be fed with 12.5v plus to get the full brightness. Normal bulbs not as bright but more tolerant. Higher rated, the sort of bulb that says +30% extra light etc, ones can be fitted and good brands are good but even they will have slightly shorter life. Keep a set of spares in the car with those. Rear lights do benefit from these as the Volvo lights are small and a bit dull. Keep the reflectors clean and shiny or add some chrome tape to them.

[Ron Kwas]

CR;

Voltage drop can occur anywhere in the path from Source to Load, resulting in the Load seeing less than if the VD were not occurring (that's why I always mention considering/checking/assuring the entire current path is without issues) . Having reiterated that, I can't fully endorse Russ's point about location near the Load (Relay location near Load would only be important if Relay to Load was wired with too small a gauge for the Load current, which again would minimize the VD in the path).

Wire is cheap compared to other components, so buy the next gauge fatter, and you can put the Relay for the Headlights in the Boot if the spirit moved you to do this (I'm not suggesting or advocating this, just making a point with a joke...fact is, Relay Headlight power, beyond the latching Hi/Lo Beam control is just not necessary IMO! See: http://www.sw-em.com/lighting.htm )

Presuming we size the wire for the expected Load current (and this can be taken from a chart), we can pretty much disregard VDs in wiring...so what is left to assure a good connection and that no VDs develop, is crimps, connections, and switchcontacts. Clean all of these to shiny metal, reconnect, assure they are snugly connected (use ACZP!), and I expect you will have maximum voltage getting to Headlights and other Loads...verify this by comparing voltage at Battery terminals to Load terminals...VD should be minimal...if not, located VD in the path and correct!

Cheers

[CLIVERALLY]

Thanks lads

[swedishandgerman]

I've done less than sod all research into what's available, but surely you can keep this really simple by ditching the foot dipper switch and ditching the old fashioned headlight flasher relay. Replace all that with one single modern headlight control relay that is operated by the wire that originally went from your foot dipper switch as your on/off and use the stalk headlight flasher as a momentary switch to go from dip to full beam. That way both dip and full beam are only powered via the relay, not the whole circuit. Okay, it means you'd lose the flasher, but it would eliminate voltage drop through the headlight switch, the dipper switch and the flasher.