MBenzNut

alright so I installed some new ccfl headlights the other night and the next morning my battery was dead. Well I figured it because I left them on auto.. Something I've never done before. Well I jumped my car and ran it for the last to days. No issues. Started right up. Hopped in this morning drove it for about 5 minutes. Parked it left it for a few hours and my battery was dead again! The headlights required no mods. New new wiring just plug and play. Any ideas what could be going on? It is a 2001 c320

tommy

Leaving them on auto wouldn't be the culprit - they would turn off automatically, especially since you didn't screw with the wiring.

Do you still have the original alternator? Could just be you need a new battery, too - they don't last too long in our cars.

MBenzNut

I believe in coinsidences. But that would bevan extreme coincidence. The night I put my new headlights in the night my battery or alternator go bad.. I'm doubtful of the alternator being bad because I let it run fora few hours and it seemed to charge. I was able to start my car probably 12 times throughout the daym then this morning it started good. No slow turn over. Them it suddenly after 5 hours of sitting was dead again.

Moviela

I am sorry, but I just don't know what ccfl lamps are. You need to do two things:

1. Check the battery with the specified battery tester. (A multimeter won't do the job.)

2. Use an ammeter to determine the current flowing when the key is out. If more than say 100mA, you need to find out who is not sleeping when the key is out. Early C class has a problem with the power supply bypassing of the seat modules. They fail to sleep and remain on to respond to seat commands.

MBenzNut

thanks I'll look it my power supply tomorrow. I'll check the head lights and seats out tomorrow. See if that narrows it down. I feel like my headlights although not on are drawing power for some reason. After all they are off eBay. I knew there was a potential risk with them. Will update tomorrow. Ccfl.. I have no idea what it stands for but its basically a cheaper version of led lamps. Nothing to special. Just was sick of my yellowed headlights.

raymond g-

let's presume that your battery was in good health prior to the headlight mod.
then, something caused a battery draw bad enough to exhaust the battery.

even if you drove the car for several days, if the battery voltage was way down
the alternators were never designed to replenish deep discharges. their purpose
is to apply maintenance charging

if the discharge resulted in sulfation serious enough to short cells, that condition
needs to be resolved.

hydrometer test is very helpful < $20 to purchase)
voltage test is helpful
voltage test under load is extremely helpful

the answers to those three tests should allow you to avoid guessing, or paying
for a new battery which may not be needed.

yes, there is also possible for the voltage regulator, or alternator to be operating
out of spec. but we need the battery operating in good health first....and if
that still results in failure to start, then we'll look upstream, ie alternator and/
or voltage regulator....followed by parasitic draw

MBenzNut

so i went to auto zone and had my battery tested.. they say its bad. but its auto zone.. I am a little weary. this morning before i did that i went outside to start my car, shocker... battery was dead. well this time i didn't jump it. i put a crappy battery charger on it. literally turned it on at ten volts (not engine start mode) and walked over to crank it over and it fired instantly.. then i unplugged it and started it in excess of ten times... with full cranking power. like the battery was never dead.... what to make of this?

edgarinho10

Sometimes the battery isn't completely dead. Instead, lets say the car needs around 500 to start and it's currently lingering around 450 or so. A small charge will be enough to get it started but since your car requieres a battery on the average of 800-900 at least, then it won't be able to start on it's own or support the electrical system of the car. Your car will be able to start immediately after the small charge because it is still within the battery but sooner or later, it will lose the charge. Sounds like it is the battery.

How old is the battery?

MBenzNut

you know.. I just looked at the battery I don't know where a date is on it. But. I think it might be the original battery its from Mercedes. I don't know who in there right mind would go to Mercedes for a new battery.. So I bought a new battery. I guess it all makes sense in some way. When I was installing new headlights I was listening to the radio. For the whole duration. When I started it that first time I know I drained the battery a little bit I'm thinking that I drained the battery below what it could handle and killed it. Guess I won't know for a couple of days. If it drains my battery again.

Carsy

Make sure the battery terminal clamps are clean of build up & are tight. A little vaseline on them to stop corrosion .

Moviela

Actually "right minded" people buy their battery from Mercedes because there is no aftermarket battery that meets the specifications of the OEM battery.

Your car has twelve spark plugs, count 'em 12, meaning you require 3 times the current to ignite the fuel as our four pot friends.

The battery is not that much more expensive than the under rated unit the auto parts store sold you. It will also outlast the aftermarket unit with a fancy prorated warranty.

Don't buy from the dealer. Call roadside. They will come and not charge an inflated price like many dealers who add a markup to the list price. Roadside will resync the car and only charge for the battery, the service is free as long as you have recently had a regular service at the dealer. You also enjoy a warranty good at any dealer.

Roadside carries a Midtronics tester, and will not sell you a battery if yours is good.

MBenzNut

Alright so I though I fixed the problem. I thought tinkering with my new headlights killed my battery to the point where it Would not hold a charge. So I bought a new battery. Well I left the car sitting for three weeks and now my battery is dead again my brand-new battery. So I checked for a drain On my battery and it is pushing 12 volts with the car off. So I dug a little deeper into it and unplugged my headlights and did another voltage check with the car off and both headlight harnesses are getting 10 to 11 volts.. What I really need is for someone to unplug their headlights and see if they are consistently getting high voltage. I can't find anything on it and I feel like that's not right. With the car locked up power off. It's also pushing the same voltage, maybe a little higher when the headlights are on. Any help is appreciated. I'm unplugging my headlights every night. It's getting old.

Moviela

Measuring the voltage at the headlight connectors is meaningless in this case. You need to measure the current to determine if the headlights are causing the problem. I think not, even if they are cold-cathode flourescents. When the car is off and the key removed the front SAM removes the power to the headlights. At this point you don't know if the new battery is good (sometimes new ones are bad from the box) or if you have a charging circuit failure, alternator or regulator, or even the belt. You need someone with the proper instruments to check the battery and charging system. Then look for excessive current being drawn when the car is off.

Raymond G's post #6 above is instructive on how you should proceed.

mleskovar

+1 and easy to check. Unplug both seat modules and see if drain stops.

MBenzNut

[quote=Moviela;5591108]Measuring the voltage at the headlight connectors is meaningless in this case. You need to measure the current to determine if the headlights are causing the problem. I think not, even if they are cold-cathode flourescents..........

I'll look at his post. I don't see how or why there would be voltage at the end of the harness before the headlight itself. With power off and headlights off. . Why is it meaningless? And how should I measure the current then? Thanks!

MBenzNut

Are they under the seat?

MBenzNut

So we are at these steps now. I went and bought a new battery. So battery is good now. All was fine I thought until the car sat for several weeks... It died again. So here Is where I'm at. I disconnected the battery ground at tested for a draw. It was reading 11-12 volts... The rest is in my new post. Thanks

mleskovar

Yes, seats. There is one under the driver's and one under the passenger's seat. If it turns out to be the seat modules there's several fixes available.

MBenzNut

So today I think pretty much eliminated my headlight idea. My headlights have been unplugged for 2-3 days and today after using my car numerous times the battery was dead. So I unplugged the seat actuators. I unplugged to harnesses on both seats. 1 big and one small. But there were others. What are they all for? Alarm? I don't know

mleskovar

If I remember correctly it's the small plug that carries the power. Red +12V, Brown ground, and Black ground (with the key off) to each module.

Seat belts...pressure switch for air bag?

MBenzNut

With my headlights unplugged and both seat actuators unplugged I'm still pulling 10volts... Frustrating me! Any more ideas?

phister

take it to an electrical shop have them run down the problem, they have the equipment to track down the issue.

mleskovar

10 volts? What's up with that? Anyway, you have to be careful when checking for draw. Anything that would keep the bus alive needs to be shut down.....just closing the door keeps it active I believe for 5 minutes? Have you had the modules unplugged over night? Or had the battery die after unplugging them?

MBenzNut

What I need is someone to test there's out. So they can tell me what they have being pulled while the car is off. No I haven't let my car sit for long before testing it. Yes I had the modules unplugged over night. The battery was pretty low when I started it the next morning. So I have a suspicion it's not that. Also when I disconnect either the pos or neg and reconnect them it's sparking which means something is starving for power. Also I have unplugged each and every single fuse in that car separately and checked the draw nothing stopped the draw. Also as a side note I busted my headlight/mirror switch assembly damn it. No headlights till I go to mercedes and buy one. Hopefully it's not bad I have no choice really. That thing shattered. No fixing it. After I get that headlight switch tomorrow I'm going to end up biting the bullet and taking my car to a electrical shop. I'm sick of dealing with it.

MBenzNut

Sometimes I wish my life could just be easier... So I took my car to a automotive electrical shop and payed 180 for them to tell me sorry. Take it to mercedes... Should have just done that. For cheaper. 145 to diagnose and they put that towards any fixes. Anyways the place told me my computer is kicking up about 40 codes. I think most of them where past codes held in the memory I have two full list of them. To mercedes I go tomorrow. More money :/ damn.