2 replies to this topic

[Serge]

I notice that when I turn on defrosters or anything that puts a heavy load on the alternator the idle dips slightly. I am assuming this is because the current drain takes power away from the ignition coil, thus reducing the power output of the engine.

Or is it that the alternator gets more difficult to turn as there is a larger load on it? I can't see how this is possible though, from an electric motor point of view.

Anyone?

[Vitor]

The alternator (and builtin voltage regulator) is designed to keep the voltage stable regardless of the load.
The defrosters put a heavy load on the alternator.
If the idle speed goes down, you may want to check the automatic idle speed valve to make sure it is doing its job and keeping the idle constant so the alternator can do its job.
Also, while at idle, check the voltage at the battery and then turn the defroster ON.
Do the same reading at the alternator output and see if there is a difference that may indicate poor connections.

[Sinbad]

Basic electromagnetics - the more current a generator has to supply, the harder that generator is to turn (basically the current flowing in the generator's coils opposes the direction of rotation - more current = more opposition)