Starting question - PeachParts Mercedes-Benz Forum

Stuiie · #1 03-23-2013, 09:17 PM

This morning I went to start the car and it cranked over like it had a week battery the first time I tried to start the car.
Then I turned the key off an tried to start it again and it lit off.
After that I did some errands driving about 10 to 20 miles or so then I shut the car off and again it started like it had a week battery for about 2 to 3 cranks then it lit off without having to turn the key off and restart it.
Im thinking it either has a week battery or charging system or a bad starter.
The battery light on the dash is not on but Im not sure how reliable that is to religh on for a definitive answer as to whether or not the charging system is working properly.
Please advise thank you.

mach4 · #2 03-23-2013, 09:41 PM

Quote:

Originally Posted by Stuiie

This morning I went to start the car and it cranked over like it had a week battery the first time I tried to start the car.
Then I turned the key off an tried to start it again and it lit off.
After that I did some errands driving about 10 to 20 miles or so then I shut the car off and again it started like it had a week battery for about 2 to 3 cranks then it lit off without having to turn the key off and restart it.
Im thinking it either has a week battery or charging system or a bad starter.
The battery light on the dash is not on but Im not sure how reliable that is to religh on for a definitive answer as to whether or not the charging system is working properly.
Please advise thank you.

The battery light on the dash must be on for the alternator to work. So that's something that definitely needs to be fixed. The symptoms you describe can be corroded battery terminals. I'd check that for sure. Obviously could be a bad battery, solenoid, starter, ground, cables and so forth, but good to start with the easy stuff first.

qwerty · #3 03-23-2013, 09:49 PM

Quote:

Originally Posted by mach4

The battery light on the dash must be on for the alternator to work.

Really?

Stuiie · #4 03-23-2013, 09:51 PM

The battery light comes on when I first turn the key on but goesout when the engine is running, the battery is new the P.O. replaced it several months before I bought the car, I wondering if it is bad connections or if it is a bad starter.
Is it possible to fit a group 31 stud battery under the hood in this car?

qwerty · #5 03-23-2013, 10:12 PM

Quote:

Originally Posted by Stuiie

The battery light comes on when I first turn the key on but goes out when the engine is running...

My car has that very same problem. Evidently, my alternator hasn't been working since I bought the car back in '83. Since it "definitely needs to be fixed," I will get right on it!!!

mach4 · #6 03-23-2013, 10:25 PM

Quote:

Originally Posted by qwerty

My car has that very same problem. Evidently, my alternator hasn't been working since I bought the car back in '83. Since it "definitely needs to be fixed," I will get right on it!!!

The original post stated "The battery light on the dash is not on but Im not sure how reliable that is...". If it's truly not on, then the alternator will not charge. The OPs follow up statement "The battery light comes on when I first turn the key on but goes out when the engine is running" indicates proper operation.

Sorry if I took things a bit too literally, but at the time of the response there was no additional information available.

Stuiie · #7 03-23-2013, 11:17 PM

mach4 sorry for the misinformation I ment to say the battery light comes on during initial key on before starting then goes out after the engine is running so if the light does not come on during or when there is trouble with the charging system or the battery then how do I know how reliable is it since there is no volt or ammeter to go by?

mach4 · #8 03-24-2013, 12:10 AM

Quote:

Originally Posted by Stuiie

mach4 sorry for the misinformation I ment to say the battery light comes on during initial key on before starting then goes out after the engine is running so if the light does not come on during or when there is trouble with the charging system or the battery then how do I know how reliable is it since there is no volt or ammeter to go by?

There is a lot of information that is not provided by gauges. For example there is no boost gauge, no vacuum gauge, no oil temp gauge, no egt and so forth. MB has provided information on the key components - fuel, oil pressure, water temperature and idiot lights for others like the alternator. It's kind of like a first cut. If there is no battery light, you can be assured you'll not have charging (the alternator needs voltage to the field in order to start charging) and the light is actually indicating that there is power to the alternator.

If you have a problem, or suspect you do, then it's time to break out the diagnostic tools - in this case a multimeter would give you a first cut on charging voltage and also battery voltage. You can't definitively test a battery without a load test, but low voltage would be a good indicator. At this point it would be good to check your battery terminals, test your battery voltage and test your charging voltage. That will provide data for any additional tests needed.

barry12345 · #9 03-24-2013, 12:25 AM

First of all to make sure it is just not slack alternator belts. See if you can turn the fan portion of the alternator. This is a common cause of an under charging alternator.

qwerty · #10 03-24-2013, 12:33 AM

Quote:

Originally Posted by mach4

If there is no battery light, you can be assured you'll not have charging (the alternator needs voltage to the field in order to start charging) and the light is actually indicating that there is power to the alternator.

Evidently, "no battery light" has a completely different meaning than "battery light not illuminated."

The purpose of an illuminated alternator warning lamp is not to warn that the alternator is operating properly.

Diesel911 · #11 03-24-2013, 10:57 AM

Quote:

Originally Posted by mach4

The battery light on the dash must be on for the alternator to work. So that's something that definitely needs to be fixed. The symptoms you describe can be corroded battery terminals. I'd check that for sure. Obviously could be a bad battery, solenoid, starter, ground, cables and so forth, but good to start with the easy stuff first.

"The battery light on the dash must be on for the alternator to work."

When you first turn the Key all the Warning Lights should go on (this checks to see if the Bulbs are working and you need a good Bulb in the Charging Light for the Alternator to charge properly).
With the Key in the run position all the wanring lights should be off unless there is a problem.

Some Members have said that when one of the Brushes was badly worn on the Voltage Regulator but the other one still made good contact the Charging Light never came on even though their Battery was not getting Charged.

Brian Carlton · #12 03-24-2013, 11:17 AM

Quote:

Originally Posted by qwerty

My car has that very same problem. Evidently, my alternator hasn't been working since I bought the car back in '83. Since it "definitely needs to be fixed," I will get right on it!!!

Me too.

I wonder if M/B will fix it under warranty since it has been this way since the vehicle was first delivered?

Who knew?

I really have an excellent battery, however, and it has lasted 10 years without an alternator to charge it.