Rear Defroster Doesn't work
 

I sent a post out last week on this and got one reply. Thank you Blackmercedes. My battery went dead on Thanksgiving morning and would not take a charge. Blackmercedes, you said it was time
to replace the battery.
I bought from a new one from Auto Zone and they no longer give the battery total power; 100Amps in the Mercedes battery. Instead they only the cold cranking amps. The new one is 680 Amps against the old 450 Amps. The new battery did not help with the defroster, which comes on for 5 seconds and then shuts itself off. the blinking light says that. I can't find the relay for it.
Anyone got another suggestion!

Dan

What year, model, miles?

Has the alternator been tested to ensure proper output? A dying battery can overwhelm and ultimately damage an alternator. How is the alternator belt? Unglazed? Snug?

For what it's worth, I had a similar problem on my S420 while it was still under warranty. MB replaced the glass stating that there was a short. Hopefully that's not your problem.
CK