Cars Dead Battery or alternator?

[krisv420]

Well my car has been acting up for the past two weeks. About a week ago i got a phone call when driving by the beach side.. I had to take the call so i pulled over and threw my emergency blinkers on. I forgot that i left my fog lights on while talking for 30+ mins. As i try to start my car the computer in the middle dims and it just makes a click sound. Looks like theres no power =/ waited for triple A for like 3 hours. Car was running fine after it was jumped. A week down the road which is the day before yesterday. I got "Light Sensor Visit Workshop" error came on, I noticed things aren't really right. When I start the car, it seems to take a little more work to start up the instrument cluster dims quite a bit and flickers when I turn the key to start the car up. Car is an 02 i dunno if the battery was ever replaced is there anyway to tell the year on it? Now yesterday the car just sits.. Because it just doesn't have enough power to start up. I really don't know if its the battery or the alternator i don't have to much cash right now to buy both.. Is there a way to test each? If the battery is holding a charge? Or If the Alternator is putting out any power? Thanks again Back 2 the forums

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[Karo]

Take out your battery. Take it to any auto store. (Kragen, PepBoys, AutoZone) and they will hook up the battery and test it. Then you can really know if it's the battery or not.

It seems like it should be the battery.

There is a pretty good chance that the battery has not been changed on the car.

Edit

I saw in your sig that you have a sound system. Maybe it might be the battery.

[krisv420]

Originally Posted by jk062602kj

Take out your battery. Take it to any auto store. (Kragen, PepBoys, AutoZone) and they will hook up the battery and test it. Then you can really know if it's the battery or not.

It seems like it should be the battery.

There is a pretty good chance that the battery has not been changed on the car.

Edit

I saw in your sig that you have a sound system. Maybe it might be the battery.

Yes i had to un-install my woofers just to get another weeks use out of the car lol. But i will take out the battery and go to a place and test it soon.

[Karo]

Here is a good thread about batteries (replacement).
Time for a new battery...suggestions?

This is what Glyn said and he knows a lot about cars.

"The OE batteries usually walk 7 years which is why I recommend them. Whatever you decide don't go with a wimpy battery - 100ah or greater. Benz vehicles have huge current draw at start"

So I would go with 100ah or greater.

He said they go 7 year Mercedes batteries so since your car is an 02 I guess it really is time.

Good Luck

[TruTaing]

Messed up seat control modules have been the main issue w/ w203s draining batteries. Search and you shall find answers.

[krisv420]

Originally Posted by TruTaing

Messed up seat control modules have been the main issue w/ w203s draining batteries. Search and you shall find answers.

I know im not a newbie lol.. But they have never givin me issues ive already tried unplugin them still no help hmm

[mleskovar]

You can determine a car battery state of charge with a DVM.

100% 12.7V
90% 12.5V
80% 12.42V
70% 12.32V
60% 12.20V
50% 12.06V
40% 11.9V
30% 11.75V
20% 11.58V
10% 11.31V
0 10.5 V

You test the alternator with a VM with the motor running. Should be 13.5V to 14.5V If you find a 100ah battery other than the OEM please let us know, I don't think you will. With your "accessories" you definitely want at least a 100ah battery. Where you are just call MB Road Side Assistance and they'll bring a battery, install it, and dispose of your old one....for a premium price...about $175 (the price of the battery)? It's worth it. Lots of short trips degrade a battery quickly. And as Tru Taing said, seat modules are battery eaters. Do you have a DVM?

[krisv420]

Originally Posted by mleskovar

You can determine a car battery state of charge with a DVM.

100% 12.7V
90% 12.5V
80% 12.42V
70% 12.32V
60% 12.20V
50% 12.06V
40% 11.9V
30% 11.75V
20% 11.58V
10% 11.31V
0 10.5 V

You test the alternator with a VM with the motor running. Should be 13.5V to 14.5V If you find a 100ah battery other than the OEM please let us know, I don't think you will. With your "accessories" you definitely want at least a 100ah battery. Where you are just call MB Road Side Assistance and they'll bring a battery, install it, and dispose of your old one....for a premium price...about $175 (the price of the battery)? It's worth it. Lots of short trips degrade a battery quickly. And as Tru Taing said, seat modules are battery eaters. Do you have a DVM?

I had a digital volt meter somewere around the house.. But i would have to get the car running first.. hmm Ive tried to jump start my car in the past but i could never jump it =/

[krisv420]

I found this battery at pep boys for 99 dollars


Product Specs
Part Number 49-850B
Group Size 49
Description Bosch S5 (Pep Boys)
CCA @ 0F 850
Ca @ 32F 1000
RC min @ 25A 120
Length in Inches 14
Width in Inches 6-7/8
Height in Inches 7-7/16
SKU# 9073755
UPC# 02885155845 7


http://c2c.activant.com/ctoc/index.j...pyDkkBUnEhBQAA

[LILBENZ230]

A related question would be the menu in dyno mode that shows voltage.. is that something you could use to determine the battery strength? Also not sure if I would trust Roadside to mess with the electronics. I've explained in other threads that the people they send are not Benz specialists. Been there, done that.

[krisv420]

Originally Posted by LILBENZ230

A related question would be the menu in dyno mode that shows voltage.. is that something you could use to determine the battery strength? Also not sure if I would trust Roadside to mess with the electronics. I've explained in other threads that the people they send are not Benz specialists. Been there, done that.

I was just going to call them in the morning and get a battery.. Theres two bolts people are talking about that i don't wanna deal with because i don't have the right tools lol. I guess ill stand right next to him to make sure my car doesn't get hurt.. I don't wanna mess up the brand new paint =D

[LILBENZ230]

It's not the paint I'd be worried about. Anyone can change a battery in a Camry. It's the sensitive electronics in these cars that blow up if you don't do something exactly right. And the one time I used roadside, it was clearly not a man who had ever done anything on a Mercedes before.

[krisv420]

Originally Posted by LILBENZ230

It's not the paint I'd be worried about. Anyone can change a battery in a Camry. It's the sensitive electronics in these cars that blow up if you don't do something exactly right. And the one time I used roadside, it was clearly not a man who had ever done anything on a Mercedes before.

I'm really ready for anything right now the car just sits in my garage so any input helps.

[mleskovar]

Originally Posted by krisv420

I'm really ready for anything right now the car just sits in my garage so any input helps.

Do you have a DVM?

[krisv420]

Originally Posted by mleskovar

Do you have a DVM?

No i lost it some place =/.. I could always buy a cheeeeeeppooo at walmart or something if its needed

[mbpc320]

If you can get the car running, you can change the battery without losing any functions. It is a two person job. With car running, you disconnect the battery and put new one in place. You need to be very careful not to let the positive connector come near either battery while you are removing it and putting it in place. Your alternator will keep the car running while the battery is disconnected (assuming no problems with it).

I had an Interstate Mega-Tron plus 85, but had problems with it so I had a Duralast Professional battery installed (had one in my 300E before and have one in my wife's ML) and have had no issues.

[TruTaing]

Originally Posted by krisv420

I know im not a newbie lol.. But they have never givin me issues ive already tried unplugin them still no help hmm

Hey, I made no mention of newbies and you didnt mention you unplugged the seat control modules :P

Take mleskovar's advice...

[mleskovar]

I hate to guess but.....If you never had the battery light go on then you can assume the alternator is OK. If you replaced the battery and it still goes dead within a few days then I would recharge the battery and unplug the seat modules first. Both sides, just the 4 wire plugs in front.

[LILBENZ230]

Originally Posted by mbpc320

If you can get the car running, you can change the battery without losing any functions. It is a two person job. With car running, you disconnect the battery and put new one in place. You need to be very careful not to let the positive connector come near either battery while you are removing it and putting it in place. Your alternator will keep the car running while the battery is disconnected (assuming no problems with it).

Nay! Do NOT do this. The battery serves other functions aside from just starting the car.

mleskovar, if I put my car in dyno mode, the first screen it shows is a voltage screen. Running the car says this: "UB 13.6V" - is this screen on the pre-facelift cars? Or is this not related to battery issues, like is this not something that you could use to tell whether or not your battery is bad. When my car is parked, it says 12.3v. During start up it runs down to like 10.5, then bounces back up to 13.6-14.4v. I was just wondering.. I don't know a TON about these cars (certainly nothing like you do) and I'm trying to learn.

[Glyn M Ruck]

Kris - new battery time - and stop jump starting the car. There is an excellent chance of blowing a SAM etc. if you get unlucky. Then a new battery will seem very inexpensive.

[krisv420]

Originally Posted by Glyn M Ruck

Kris - new battery time - and stop jump starting the car. There is an excellent chance of blowing a SAM etc. if you get unlucky. Then a new battery will seem very inexpensive.

Haha i only jumped the car one time after i failed i never tried it again. I was awaiting your reply alright well i will call MB road side and get a new one.

[krisv420]

Originally Posted by mleskovar

You can determine a car battery state of charge with a DVM.

100% 12.7V
90% 12.5V
80% 12.42V
70% 12.32V
60% 12.20V
50% 12.06V
40% 11.9V
30% 11.75V
20% 11.58V
10% 11.31V
0 10.5 V

You test the alternator with a VM with the motor running. Should be 13.5V to 14.5V If you find a 100ah battery other than the OEM please let us know, I don't think you will. With your "accessories" you definitely want at least a 100ah battery. Where you are just call MB Road Side Assistance and they'll bring a battery, install it, and dispose of your old one....for a premium price...about $175 (the price of the battery)? It's worth it. Lots of short trips degrade a battery quickly. And as Tru Taing said, seat modules are battery eaters. Do you have a DVM?

I have a jump starting thing on my battery right now.. The reading came out to 10.5 -10.6

Going to see if it will charge.. If the battery will not hold a charge then its the battery correct?

[C230 Sport Coup]

[Glyn M Ruck]

Yes - but at that voltage if the charge light is not coming on the battery is shot.

[C230 Sport Coup]

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