Battery Idiot lamp

[crhenkel]

Does anyone know if installing an LED lamp in place of the 3 watt oem bulb in the battery charge idiot lamp would cause alternator charging problems?

Some have said that if the bulb is burnt out or not the correct wattage, the charging system will not work properly.

About the time I changed all the idiot lamps in my cluster to leds that are much brighter and more vibrant colors that are easier to see during the day, I started seeing a low charging issue with my alternator in my 1986 190E 2.3-16valve
It has a volt meter and it shows as low at 9 volts at times with the blower motor on high, the radio on, the headlamps on, and the rpm up.
It has a new rebuilt alternator, voltage regulator and the cables test out good.
Driving or reving engine increases the charge some, but not much. With everything off and driving the car, I can get the volt meter to register over 12.5 volts but as soon as I turn something on, it drops like a rock. It is a 70amp alternator.

Thanks