Hello.

Tonight I ran out to my car to grab something and quickly realized I had left my power seats in. Scared to press the unlock button, I did, and to my bitter surprise, my battery was dead.

This is my first time owning a Mercedes and I hate to say it, but I've heard horror stories about the battery dying.

What is the proper protocol to take to get my car back up and running? The battery is new (I think 2 months at oldest), and the reason it is dead is because of the power seat problem.

Should I treat my car like a normal one and jump it? or will that mess things up? I've also read that things won't work afterwards (windows, sunroof, CD player). Why is this? How can I ensure that this isn't the case.

What steps do I need to take to resync it? All my others cars I would just hook up jumpers and go. Concerned about this one. Ugh.

I did not remove the battery, and the key was not in the car while the battery died. It simply died overnight.

My car: w203 C320 Automatic. 105k miles.

Please help! thanks.

 

you can probably jump the car, does your headlights turn on for awhile, if it does the battery is not completely dead so a jump will be ok and just let the car run for awhile to charge it back up. If you need to remove it, do it in the proper order, 1. remove negative terminal first 2. remove positive next. 3. Remove battery, 4. on install do in reverse order, positive then negative.

To resync its easy and is explained in the owners manual. for all windows, just roll the windows down then hold the up switch till its completely up. test them by doing the one press, this goes the same for the sunroof.

for the ESP light, turn your car on and turn the wheel from lock to lock a couple of times, (all the way left and all the way right) itll go off after awhile.

 

our cars have a lot of modules and electronics running things so sometime removing the battery incorrectly can short things out making you have to spend a few hundred to replace them. I've removed and disconnected my battery many times with no issues so far, no CEL or issues.

 

phister, thanks for the reply.

unfortunately, she is out cold. no headlights, no cluster, nothing. can I still jump it or use one of those portable battery chargers?

If I do take it out, what's the next steps I should take?

Really don't want to mess this up.

Thanks so far for the help.

 

you can probabaly jump it just to get it running and just do the normal resync. drive around for awhile to see if it charge up the battery and then see if it'll restart after turning it off.

 

I'd disconnect the neg terminal, and charge it.
Yes, you can jump it but it's out cold, it's gonna take a while to charge,
and then when you stop, you'll have to wonder if there's enough juice to start.
+ that puts stress on your alternator.
Ever notice, people seem to blow the alternator about the time the battery
dies and turns into a giant resistor?

Charge it and get it checked at any auto parts store for it's current
CCA.

 

Charge it with a portable charger? Is this the safest route?

What's CCA? Thanks man!

 

CCA= Cold Cranking Amps at 0 degrees

You want at least 720 CCA and 900 Cranking Amps

I have the Interstate MTP-49/H8 when I replaced mine. You can do that or call MB roadside assistance and get an OEM replacement.

 

If the battery is dead, take it out and have it charged using the protocol specified by the manufacturer. You don't want to sulphate a 2 month old battery. While the battery is out, unplug the offending seat modules and send them for reman...

Disconnect the SAM's, and put the battery back in. Reconnect the SAM's and drive happily.

If uncomfortable, call roadside (number on the visor) and get help. If you don't have an OEM battery, now is the time to get one. Roadside prices are competitive, and you get a battery with enough poop to operate all the consumers in your car. Aftermarket batteries fall short of meeting the specs.

 

Check out that book thingy in your glove compartment,.... the owner's manual. MB does NOT recommend jump starting the car. MB recommends smart-trickle chargers,.... basically those Ctek chargers.

Oh,.. and check that sticky thingy at the top of the forum,... about battery,...

 

I looked through the manual and found everything I need. Was not aware they have special "under the hood terminals" for the battery.

You say MB does not recommend jump starting. Where did you get this from? It wasn't anywhere in my manual and they had instructions on jump starting it.

Would a place like autozone have a smart-trickle charger?

Double checked the battery, and it's a duralast gold. Bad?

Thanks

 

Where can I find the preferred charging method? Couldn't find it in the book.


Any instructions on how to disconnect SAM's? That is what I am most worried about.

 

just remove the battery the way the manual says. neg then positive and you'll be ok. Mine died and i just removed it that way and nothing went wrong, just had to resync everything once I installed it back.

 

Remove the battery to charge?
Why not just disonnect the neg terminal?
Once charged fully have it tested to make sure it's not on the way out.
Our cars do strange things as the battery slowly fails. It's designed like the human body in the cold, it cuts off the power to non-essential systems one at a time. 1st the radio, then the climate control, then....I dunno, I kept checking mine till it got to 400 CCA and then I replaced it.

I've read a lot of threads, people going wtf? Don't be one of those people.

Don't wait till it's completely gone, you'll probably be looking at an alternator replacement as well.

 

another warning light is sometimes the ESP light going off when the battery is going low.

 

I have seen Duralast battries at AutoZone. It seems like a house brand. They look like Johnson Controls cases so they are probably the manufacturer.

Duralast has done several things to hide the real specs of the battery, like using two different ways to calculate the CCA (cold cranking amps) and then contradict themselves on the website. The H8-DLG is shown as 850 (EN), then 900 (BCI), then the true CCA rating of 760 (EN). EN is the European standards agency, and BCI is the Battery Council International. The latter is a trade group that calculates CCA by increasing the CCA (EN) by twenty five percent. Makes the battery look more muscular.

What AutoZone is not saying is the amp hour rating of their battery. American Mercedes cars with their abundance of electrical devices need a 100 Ah unit. The CCA for this is about 830 (EN.)

The Duralast Gold in AutoZone's catalog for a C320 is rated 760 CCA (EN.) The Ah rating for battries of this type is about 77. Too small for a long life in Mercedes cars. The battery AutoZone specifies will fit ROW cars that do not have all the electrical googaws. So they are technically correct, but not for US spec cars.

Johnson Controls is the owner of the Varta brand, and in Europe a Varta Silver is properly specified for the OP's car. The Varta catalog also has good advice on charging and testing. Generally charge at ten percent of the Ah spec. So the 100 Ah battery should be charged at 10 amps until there is no further increase in the terminal voltage and specific gravity for two hours. The Duralast battery does not tell you the Ah rating, so you cannot know the proper charge rate.


http://www.varta-automotive.com/file...Folder_car.pdf


Can you use the Duralast in a Benz? Sure, but I would hate to come off the mountain "apree-ski" and discover the car won't start.

A genuine OEM battery from MBUSA roadside is about the same price, and is a 100 Ah unit.

 

Good advice as they last up to 8 or more years.