alternator?

[sprinternut]

97 Sprinter 310D.Battery warning light glows dimly when load is put on the alternator, e.g. lights/heater.Output voltage when engine running at idle is 13.02 volts-does it sound like the alty is on its way out?

 

[television]

I am afraid that is diode gone down in the alternator, you could ask a Bosch service center if they can fix it