2003 MCS, 70k miles

Wife went to go to the store today, battery is totally dead. (btw. Ready to kill the engineer that thought it was smart to put the battery in the trunk on a car that the trunk will not open when the battery is dead....)

Battery was the original so I went and got a new one in the hopes that nothing else would be wrong...( yeah right)

replace batter and start car, battery light is on, guages work on and off, power steering is intermittnet.

serp belt is still attached

charging voltage at the battery is 16.5v at idle (if memory serves back in college I think we learned anything over 14.8 is bad)

My conclusion based on how I think the voltage regulator works on this car: The voltage regulator is toast and instead of sending voltage to the proper places its sending too much to the battery ( which explains the high charging voltage) and not enough to the other systems in the car.

Anyone have any idea if I'm right?

 

there's a cable under the rear seat that will let you manually open the boot. I had the same thing and it was the alternator, not sure if an old battery (i have an 03 as well) over stressd it and started burning it out or if it was just old.. it is a wear part, so a 7 year run is pretty good. I would get that swapped. When they pulled mine out they said one phase was toast, put in a new one and no issues.

phil.

 

+1 for battery replacement. If your alternator is reading 16.5V, it sounds like the voltage regulator is attempting to compensate for the lack of battery voltage. I have heard if you continue running only on the alternator, you can burn it up.

If memory serves, the release cable did not exist in '02 and part of '03. Even if you cannot open the boot, you can always attach cables to the frame and positive terminal under the bonnet. That would get you power to open it up.

 

I had this happen when my electric power steering pump went out. Listen for the fan underneath the power steering not going off and draining battery.