txhokie4life

I'm getting back on the road with my '82 Euro.

A failed Alternator shortly after I bought the car in January
started a huge -- WYAIT project.

I even took the cluster out and checked the battery/charger
indicator lamp. It seems to work stand alone -- but never
did in the car (I'll check that out later).

However, to make progress on the alternator -- I mimic'd the behavior of
the battery/charger igniter circuit by taking three lamps
I had replaced from the cluster -- put them in series and
connected them between switched power and the igniter pin on the alternator.

The behavior I observe is that the lights light when Key On Engine Off
as is expected. However, when I start the engine, the lights are still on
suggesting the alternator is not generating voltage yet.

If I get the RPMS up to 1700-2000, I observe the lights go off and the
alternator appears to be charging the battery (about 13.2-13.4v).
Once starting to charge -- I have not noticed it stop charging
even at idle -- but I have limited testing.

I need to check the voltage at the alternator and also start cleaning up
my ground points. -- But that is also on the list of projects.

Right now I'm trying to figure if that is how the alternator is supposed to be working.

The alternator is a Bosch 90Amp.

I had thought as long as there was a voltage supplied to the igniter post
and the alternator was spinning it would start charging.

It seems to act as it needs 2K RPM and then self ignites suggesting the
igniter circuit is not needed? (I haven't tested this theory yet)

Just want to know how it should work.

thanks,

Mike

WallyP

The original set up for the exciter circuit is for the warning light and a parallel-mounted 68 Ohm resistor to furnish the exciter current.

If the exciter current is low, the alternator will not charge at low speeds until the engine speed goes higher than idle - from 1200 rpm to 2500 rpm, depending upon the alternator model and the exciter current available. Once the alternator starts charging, it is self-exciting until the next restart.

Once the alternator starts charging, you should normally see 13.6 to 14.8 volts, depending upon the state of battery charge and the resistance in the myriad of connections between the alternator and the battery.

txhokie4life

Thanks -- yes I saw somewhere that the effective resistance was about 46-48 ohms.
The three bulbs I used was right at 48 ohms measured on an ohmeter.
I can try to lower the resistance some more with a parallel resistor to
see if it will ignite at idle.

I can live with having to blip the throttle -- but I don't want to cause any damage to my alternator
and would prefer to get it working properly.

thanks,

mike