Some of the warning lights on my wifes 2000 C280 stayed lit during her morning commute.

While doing a little research I came to this site and tested my battery.

http://www.repairfaq.org/ELE/F_Car_Battery.html

In testing the charge of the battery, you first have to eliminate the "surface charge", or the charge done by driving the car and then measure the charge:


REMOVE SURFACE CHARGE
If you have just recharged you battery or driven your car, eliminate any surface charge by one of the following methods; otherwise, go to the next step:


Allow the battery to sit for two to three hours or
Turn the headlights on high beam for five minutes and wait five minutes, or
With a battery load tester, apply a load at one half the battery's CCA rating for 15 seconds and wait five minutes.

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6.3) STATE-OF-CHARGE TEST
Using the following table, determine the battery's state-of-charge:

Open Circuit Approximate Average Cell
Battery Voltage State-of-charge Specific Gravity
12.65+ 100% 1.265+
12.45 75% 1.225
12.24 50% 1.190
12.06 25% 1.155
11.89 0% 1.120


The most common charging system failure is a loose, worn or broken alternator belt, so check it first. If OK, then with a known good battery and the engine running at 2000 RPM or more for two minutes, depending on the load and ambient temperature, the voltage should increase to between 13.0 and 15.1 volts. Most cars will measure between 14.0 and 14.5 volts on a warm day.


Looking at these numbers, I'd check the battery again after it has rested 3 hours and check the alternator as it seems your charging voltage is low.

glenmore