Well here's the latest. Got home last night, took it off my 1.5 amp charger and tried to start the car. It turned over once, and that was all. So I jumped it from my sons benz. Don't know if the charger just didn't have enough amps or if it had poor connections. I've never been impressed with this charger. (Come On Santa!) On the way home I stopped at an indy who lives down the street and he gave me a simple device to check the battery/charging system. With the car running and no electrical load, the lights on the device indicated a good battery. Under load it pointed to a bad alternator. Drove about .5 mile to the indy that lives down the street. He connected me to a more advanced instrument and found that it was only putting out barely 11 volts. We concluded I need to look for an alternator or repair the one I have.

Not to be in opposition to other posters here, the best possible charging situation for an older battery is a 2 amp or trickle charge over an extended period of time. High amp charges do nothing to fix the fundamental problem.

The car charging system does not decalcify the plates the way a charging box does and hence the reason batteries deteriorate over time. The best medicine for a battery is to take it from the car and put it on a low amp charge for several days. The ideal situation is to have a replacement battery already charged that can be swapped in while charging.

my .02

steve a

Thanks Steve, I'm hoping the batt. hasn't been damaged by being drained. I have it back on the 1.5a charger. One thing worries me though. After 21 hrs. on the charger it still didn't have enough to turn over two or three times much less start the car.

Hi
You may have both a bad battery and bad alternator. If the alternator isn't putting out 13+ volts a idle you need to get it fixed.

Many Mercedes batteries have removable caps on the cells. A quick test with a hydrometer will ID bad cells. There is usually a round sticker on the battery giving the date it was sold (or made) in code with the last number being the year.
Joseph