Red66GT

My car had been acting strange over the last month....like gremlins were taking over. And I finally realized what was happening...the battery's life was ending. Here's the symptons, and if you start experiencing them, you will know why ahead of time!

First I was getting errors in the display for the ESB, and other brake system warinigs. These were sporadic, and would not come up every time I started the car. However, as the battery wore down they were becoming more frequent.

After this started, I also noticed at night that my headlights would go dim for a split second and this would occur about every 5-10 minutes or so.

Last symptom, right before the battery gave up, my radio would stay on when I shut the car off! I was unable to use any controls for the radio....on/off, volume, change stations, play a cd. The radio would stay on whether the key was on or not. Eventually after cycling the key a few times it shut off.

The very next day after the radio incident, I got into the car in the morning and it started fine. The radio seemed to work fine. We drove to breakfast, and when we were done, came out of the restaurant to start the car, and it was dead. Got a jump, drove it home and put it on a trickle charger. Next day drove it to a mechanic friend and he put his tester on the battery and lo and behold, it had given up.

I figure the reason the headlights would dim for that split second was that was the regulator "turning on/off" the alternator. Since the battery wasnt sustaining any load, the alternator was working overtime.

Once I got the new battery in and went through all of the re-set procedures, everything has been working fine for over a month now, so I can say with certainty these were all due to the battery.

I also bought an Interstate battery rather than the Mercedes battery (mostly due to cost). And the only difference was the size and location of the battery vent. The Interstate battery has a breather that is just a little bigger, and it's farther away from the vent hole in the floor pan. To remedy this, I just purchased a short length of windshield washer fluid hose (it's the clear hose you can get at Pep Boys) and used that....see the pics. The white battery on the bottom of the first pic is of the Mercedes battery. You can see the 90 degree vent coming out of the side of the battery. On the Interstate battery, the vent is in the center/back side of the battery.

On a side note, other symptoms are power windows getting really slow or not working. Same with the sunroof. I whitnessed these symptoms on a truck I previously owned.

Cheers!

ohlord

job great tips

dan_cobb

happened to me before my battery needed replacement.

I can't understand why the radio would continue to work if the battery was on deaths' door OR if the ignition was off, but it did.
+++

sg_william

my car also had familiar problems, i chanched the battery, and the car spent like a month or more without problems, but again my car EVERY WEEKEND only, primarily friday's morning when you are coming to stop at the corner, it would stop the engine, it feels like an injection pump failure, after some minutes it would star normaly..... but we dont know, even MB specialists, we love this car, but we are just tired of this issue, have you ever heard about this problem???

RDD

I had my battery replaced by Mercedes Roadside over 2 yrs ago after my old indy mechanic used a non-MB battery just a few months prior. I paid <$100 for it from MB and it comes with a 2-3 yr warranty -- brand new battery even if you are responsible for killing it yourself. I paid well over $100 for the battery my indy put in.

ohlord

roadside is well past 100 bucks now and a non mb battery of oe specs can be had for less then 80 if you install it yourself,your indie did not know what he was doing if the battery he put in failed in two months(was there no warranty on it?)
ohlord

Air Marshall Eldritch

Very interesting thread. This may explain my random BAS warnings and funky sunroof control. My battery must be close to 6 years old by now.

blueC230K

Thanks for the tips. As a side note, does anyone know if these batteries are recharageable? Just wondering.... We drained one because the headlights were left on the whole night

MilitaryBenz

good info man sure this casn definitely help lots of members here, get a yellowtop fellas!!!

Red66GT

I'd stop and get the battery checked out. All they have to do is hook up a load tester and they will be able to tell you if your battery is on its way out or not. Make sure you go somewhere trustworthy and not someplace that just wants to sell you a battery!


They are rechargeable, however sometimes if they drain completely, they will not fully recover. Put it on a charger and see how it does.

ohlord

if you ever drain a battery down to dead,jump start it if you need to get home.But when home always put it on a charger overnight to fully charge.The alternator and voltage regulator were never meant to charge a fully discharged battery and using the cars charging system to do so can harm the alternator and shorten battery life.
and always charge it with the key out of the ignition

bltserv

The slow window and sunroof are the dead giveaway. My CL has sucked up a battery about every 16 months. I think somewhere there is a drain but the dealer insists its normal. Just a case of the too much electronics in my CL.
I think letting roadside do it is still the best deal.

raymond g-

Good tips all around. noting the symptoms as indicators is useful, though can
be anecdotal and may lead one to draw a flawed conclusion, ie causal effect.
Better that one test the battery from several angles, as performing a limited
number of tests only measures a slice of the battery's health, I opine.

A thorough check should include:
- determination of the battery construction (simple lead acid, gel, absorbed
glass, etc ) which may require specialty charger
- check fluid level (best to use distilled water to replenish)
- check of the specific gravity using a quality hydrometer
- voltage test (over time, static, and under load)
- slow charge for several hours (and as ohlord says, not via alternator). fast
charge generates unwanted heat which isn't conducive to long life. charge
should be performed at a rate roughly 10% of the battery's capacity.

hineywineries

You may have a BCM or CAN bus not going to sleep. It appears your battery may be deep cycling and causing early failure. Car batteries are not designed to deep cycle.

RED66GT,
Thanks for the in depth sharing of information. Many here don't even post unless they have a problem. Then they ask for help, and once they get the help, they never bother to report back or thank anyone. Your input is refreshing.

When I went through electronics school back in the days of vacuum tubes, I was taught imperical electron theory. Through the many years since, I have learned that electrons don't always pay attention to theory. That being said I'm going to do a thorough diagnostic on the battery in my wife's 97 SL320.THe climate control and radio displays have been wigging out on ocassion, and the other day after she made a stop on her way to work, the car would crank but not start. We had road service tow the car to the shop. It still wouldn't start after it was unloaded. Sometimes a failing fuel pump will function again after being bounced around during towing. A half hour later the car started. I've been driving it for a couple of days, stopping and starting, without a problem. I can't diagnose what ain't happenin.

As a last comment, you can't get a much better battery than Interstate. You can go to an Interstate warehouse and see a pallet of white MB batteries. I have never been able to prove whether Iterstate manufactures them or just distributes them. Since I am not a franchised MB dealer, I was told I can't buy them.

72chevy4x4

[QUOTE=Red66GT;2557425]

Once I got the new battery in and went through all of the re-set procedures, ////


what do you mean by 're-set' procudures?

ohlord

the radio code,the windows and the sun roof so they all open in unison also turn the steering wheel all the way left to right several times to set the steering angle sensor so the abs esp lights go off.
it's all in the manual.

ohlord

hineywineries

Update on 97 SL320. Remember I had it towed to the shop for a crank no start condition. Has been working fine since. Go figure.