1994 BMW 325

If there is no problem with the charging system (undercharging) is there any problem with the battery? If not
There might be a resistance problem in the circuit board. The circuit board should be remove and inspect.
Let me know if you want to check the charging system.

The battery can look "ok" with 12.60 volts, but in real action with the aternator running, it sometime can't keep up if there is dying cell inside.
Start with basic by checking the alternator drive belt for evidence of cracking, fraying, glazing,
replace it if you see thoses. Because a slipping belt can cause low charging derfor cause the dash light to flicker.

To test maximum charging system output, you will need to connect a load rheostat to the battery. Then connect a jumper wire to the field terminal on the alternator and the battery terminal to provide a full field. Connect a voltmeter and ammeter to mesure total output.
Increase engine speed between 2000 and 2500 rpm. You should get between 13.8 V and 14.5 volt.
If less than that then the system in underchage.

Sorry I may be made it complicated.
If you a multimeter and do not have a rheostat.
Connect the read lead to the positive cable and the black to the negative cable of the battery, the multimeter should be on scale for battery voltage.
Start the engine. The base voltage should increase by appr, 2 volts. If the charging system is working properly,
now place a load on the alternator by turning on the headlight, heater, radio.
Increase the engine speed to about 2000-2500 rpm.
The voltage should now read between 13.8V and 14.5V
switch your meter to the AC scale and be certain that your AC ripple current is not excessive, indicating a failled recrifier diode(s)

if you do not have a multimeter, drive to Walmart, ask them to test your battery and you alternator.
They may do it free.