Voltage drop?

[simonpen]

My Coupe suffers a loss of revs when the lights are turned on. Eventually the engine will stall. I have an electric pump and an alternator. The revs start to drop the instant the lights are turned on. What, in terms of electrical principles,  might be happening?

[lancialulu]

Lights should draw max 300w which is less than 1/2 horse. May be you have an earthing problem affecting the volts to the coil?

[davidwheeler]

If in doubt seek out, remove and clean all earth points.   They are notorious for doing this sort of thing.   It would be interestin to know the voltage across the battery when you switch on the lights.  It may even be the terminals themselves at fault.

[simonpen]

Thanks both. It looks as if the neg terminal may have been the culprit. The screws in the clamp were very loose and I had not tightened the clamp properly. In between times I have been to a tuner of engines and it is running better at idle as well so now when the lights are on it keeps going. ta