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Ron Kwas · Dec 25th, 2010, 01:26

Woodman;

Remember, the size of you battery matters little unless you plan to power the lights without engine running...that would be an unsustainable condition...your charging system must as a general rule support your maximum expected loads under normal operating conditions...if it doesn't, the battery will need to contribute, and this means discharging it, which is an undesirable condition...the bottom line in your case: If you have a 55Amp Alt, you have plenty of on-board electrical power, so no worries there!

I have several suggestions regarding installation...

I would never power fog lights by running the additional current through the oe light switch (the additional current would surely shorten its service life), but instead power them by way of a relay* wired for the coil to receive control power (high side) from the dipped lighting circuit, and the chassis connection (low side), from a switch on the dashboard, which would then energize the relay and apply (fused) Ignition Power (from Fuse2 on an Amazon) to the fog lights.

Wired as such, the front fog lights would only be able to be energized when the headlights were on and in the dipped state (typical requirement per regulations in EU countries), and they would go OFF automatically when engaging the hi-beams (also desirable)...they would come back ON automatically when switching back to dipped lights. [This suggestion is incidentally valid for foot-switch or latching relay controlled lights.]

As far as the rear fog light goes, that should be powered by its own relay** which takes its chassis connection (low side) from the same fog lights control switch, and its control and power from the same Fuse2. It would stay ON any time the control switch was in the ON position and irrespective of the automated switching of the fronts.

If this explanation is a bit much to digest and realize into actual wiring, let me know and I can sketch it up into a diagram and post this.

Cheers from Connecticut!

* Relay should be of the type which has coil and high-current contacts separate ( 4 terminal relay, at least), because both high side and low side of coil need to be controlled, and this circuit is separate from the load circuit.

** This relay may be a three terminal type where coil power is routed through to power the load when relay is energized.

Dec 25th, 2010, 01:26	#5
Ron Kwas Premier Member Last Online: Today 13:22 Join Date: Jul 2007 Location: Connecticut, USA	Woodman; Remember, the size of you battery matters little unless you plan to power the lights without engine running...that would be an unsustainable condition...your charging system must as a general rule support your maximum expected loads under normal operating conditions...if it doesn't, the battery will need to contribute, and this means discharging it, which is an undesirable condition...the bottom line in your case: If you have a 55Amp Alt, you have plenty of on-board electrical power, so no worries there! I have several suggestions regarding installation... I would never power fog lights by running the additional current through the oe light switch (the additional current would surely shorten its service life), but instead power them by way of a relay* wired for the coil to receive control power (high side) from the dipped lighting circuit, and the chassis connection (low side), from a switch on the dashboard, which would then energize the relay and apply (fused) Ignition Power (from Fuse2 on an Amazon) to the fog lights. Wired as such, the front fog lights would only be able to be energized when the headlights were on and in the dipped state (typical requirement per regulations in EU countries), and they would go OFF automatically when engaging the hi-beams (also desirable)...they would come back ON automatically when switching back to dipped lights. [This suggestion is incidentally valid for foot-switch or latching relay controlled lights.] As far as the rear fog light goes, that should be powered by its own relay** which takes its chassis connection (low side) from the same fog lights control switch, and its control and power from the same Fuse2. It would stay ON any time the control switch was in the ON position and irrespective of the automated switching of the fronts. If this explanation is a bit much to digest and realize into actual wiring, let me know and I can sketch it up into a diagram and post this. Cheers from Connecticut! * Relay should be of the type which has coil and high-current contacts separate ( 4 terminal relay, at least), because both high side and low side of coil need to be controlled, and this circuit is separate from the load circuit. ** This relay may be a three terminal type where coil power is routed through to power the load when relay is energized.