Drove it yesterday, it was fine; this morning, engine won't turn over at all. I've read that these cars won't unlock if the battery is dead (keyless worked without a hitch), so could it be the alternator? Radio works, all gadgets on the dash come to life, just doesn't make a sound when I turn the key. A couple of weeks ago this happened and a friend checked the battery. He said it had no fluid in it whatsoever. Aren't they supposed to check that stuff when you take it in? He added fluid, charged the battery overnight, it worked fine until now. I get no warning indicators or "malfunctions" at all (except one of the fog lights is out). Anyone have any ideas?

 

OK, I'll take this one. Here's the deal. First, let's talk about your battery. Yes, you would think that most shops would check the battery when you go in for service, but obviously, they don't. They want you to believe the battery in your car is "sealed" or "lifetime" or some such thing. It's not, believe me. Your battery is probably the original. If it is, it has screw caps on top of it like any other battery, and checking the level in the battery is as simple as it always was....just carefully remove the caps with a WIDE flat-blade screwdriver and look down in there with a flashlight to see the level of each cell. The level should NOT be all the way to the top of the hole. The caps will have some plastic protruding down from them. You want the level in the battery to just come up to that extended piece of plastic. Add DISTILLED WATER ONLY!!! And add it slowly. Easy to overfill it.
Just add a tiny bit and look again. OK>now, why your car won't start>>>>It is probably 99% your battery. And 1% chance your alternator is gonzo. To check it, do one of the following things: Take it to any AutoZone, PepBoys, etc. kind of parts place near you, and ask them to bring their tester out to your car and check your battery and alternator. This is a FREE service. These places are there to sell you parts. So, they are happy to check out those things for no cost. It will check your alternator to see if it's putting out enough charge to keep your battery alive. If it is, fine. If the battery is fully charged, great. Leave and say thanks. Now start looking for something that might be draining your battery. Anything you might have left on? Could it be the dreaded "seat module" problem in this model car? I don't know. But, DO NOT buy a battery or an alternator before you get them both checked for free. Period. Free is good. Expensive alternators you don't need is not. Right? OK>>>Your battery just sitting there should have enough power with the car shut off to work the headlights, horn, etc. Try them. Working? Good. Headlights very dim? Not good. With the car not running, that points to the battery. The alternator should show about 13.8-14+ volts going into your battery when it is charging the battery which is only when the engine is running, obviously. The battery resting by itself, no engine on at all, should should at LEAST 12 volts. If not, it may be time for a new battery. And be sure nothing is draining the battery like a dome light, etc. Hope this helps you out.

 

Thanks. I'm going to have to assume it's the battery, since this happened before, for no known reason, and I can't drive it anywhere because it won't start. Can't jump it 'cuz it's in the garage. I don't have power seats, and I always check the vanity mirror before I get out of the car - it has a habit of lighting up even when shut, so I don't know what else could drain it. But last time it was almost at 0 amps. It was fully recharged, but has died again anyway, so it's probably best to just replace it. It's past it's prime anyway. I'm thinking Sears Diehard, unless you like something else.

 

I certainly can't argue with 'mrcoyote's analysis of your problem. I have one thing to add. If the battery is the original or fairly old, you can charge them but they will not RETAIN the charge. The fact that you also charged thebattery that had a large percentage of new water would tend to support this theory. I check my batteries at least once a year and add distilled water every time. Even though they are 'sealed' they still consume the acid.
I also doubt the alternator would go from OK to totally dead overnight. In my own experience an alterator tends to slowly wear out instead of dying quickly.
Push or pull the car out of the garage and get it jump started. You'll have to re-synch everything (sunroof, windows etc.) if you replace the battery. Your manual should help you out.

 

I find it really odd thatthe batterywon't retain the charge - I believe you, cuz the guy who came to tow me some time ago said the same thing about the battery. He had a recommendation for a new brand, but I forgot what he told me. Never heard of it before. As for re-synching everything - sounds like an ordeal! Would a battery place (like NTB) know how to do this?

 

I suspect that the only place that can do a total re-synchronization is your local MB dealer. Having said that, it is very easy to do yourself. Your manual should cover all the necessary items.

 

Mr Coyote - can u please help me out??? l have a similar problem with my '98 C230. My car won't turn over. The battery is not that old -- replaced maybe 3 yrs and 18K miles ago. l don't drive the car that much, but it basically never fails to start. Then all of a sudden -- dead??? Very strange. l thought that it was the alternator because all other electrical works fine. What is your opinion?
thanks,
Mike

 

Hi Folks - l need some help please. l have a problem with my '98 C230. My car won't turn over. The battery is not that old -- replaced maybe 3 yrs and 18K miles ago. l don't drive the car that much, but it basically never fails to start. Then all of a sudden -- dead??? Very strange. l thought that it was the alternator because all other electrical works fine [windows, seats, radio, lights, etc.]. What is your opinion?
thanks,
Mike

 

I hooked my car up to a good battery charger, and after an hour it started up. So, I guess it is the battery.

 

You mentioned your battery is three years old with low mileage.
That is not a good thing for a battery. Long periods of inactivity coupled with short trips can kill a battery. The best environment for a battery is daily charging and longer trips to fully charge.
However, every battery slowly wears out to the point where they will not hold a charge.
A myriad of things can affect battery life from inactivity to car accessories like heated seats and steering wheels to rear window defrosters. Even sitting still in traffic with accessories on can slowly discharge a battery.
With your driving habits, the occasional battery charge definitely won't hurt.