Flat Battery - what to do?

mcat · 03-09-2007

My SLK has been parked up for the last couple of months and now the battery is flat. I tried it about 4 weeks ago before going on holiday to Australia and it worked fine. Now I am back it is completely dead. I guess it was too much to hope for.

Lots of questions ...

1. Is it a case of a simple jump start to get it going? Anything I need to watch out for?

2. Will all the electronics still work fine?

3. I have the roof module fitted. Any issues getting this going again?

4. Will my service interval clock still read correctly?

5. Have I done damage to my battery by letting it drain like this?

6. How long will I have to drive around to get it fully changed again?

7. Anything else I need to be aware of?

Thanks in advance

Tslick · 03-09-2007

Bumping this back to the top.

There are precautions to take into consideration. Others like Dan would know the proper way to recharge the battery, let alone jump starting.

**Ynot** · 03-09-2007

That's happened to a handful of members already, no need to worry about it. I'm one of them. I have a battery charger, I let it charged overnight and started up the next morning, got the "roof error, visit workshop", unplug the battery for 10 minutes, and the error went away, off I went, drove around town for 15 minutes and it started just fine the next morning. It's been a few weeks, everything is fine.

DansSlk · 03-09-2007

OK from the top.

1- Do not jump start the car whatever you do worst case is you have to start a donor car and connect the jump leads to the battery with the SLK shutdown the donors voltage regulator should provide about 14 volts to the battery acting as a good charger but remember it wont control the voltage at all and you can over-charge the battery so its best to leave it connected for say 5 Min's then disconnect and check the SLK's voltage anything above 11.8 in key position 2 and the car will start if its below that re-connect and wait another 5 Min's. The proper way to do this would be buy a battery charger that will switch to trickle automatically when full.

2- Yeah they will be fine so long as you don't operate anything while charging just leave the car alone and disconnect the charger / donor before doing anything even opening a door.

3- Ynot's covered this one.

4- Yep its stored in EEPROM

5- These are not deep-cycle batteries they are not designed to be drained just to give a jolt of energy to the starter and then be relieved by the alternator a few discharges wont do any noticeable harm but if you plan on leaving the car i would recommend a trickle charger because repeated cycles will cause a noticeable voltage retention issue i.e. it will go flat all the bloody time.

6- Using a trickle charger about 30 Min's to restore the voltage lost in the start and also to get all the fluids up to temp after sitting if your using a donor then prob nearer an hour / hour and a half to get it back to full charge these alternators are designed for low parasitic drag not high performance.

7- Not really mate no as i say don't activate any of the electronics while charging and make sure the charging source is disconnected before powering up the car and if your using a trickle charger use the power terminals provided not the battery the car should accept the charger on those points OK but for a donor connect directly to the battery for the damping effect, again for donors standard stuff connect the leads to its battery then start it then connect the leads to the SLK and remove them before shutting down the donor otherwise you will be draining both battery's starting the donor for the charger connect the lines then connect it to mains power after.

The charge points are the positive under the red cover on the pre-fuse box near the electronics box under the hood and on the chassis to the left of the box you will see a few different harnesses joining up to the metal under the bolt you will see some un-lacquered metal on the connectors hook up the chargers negative to them otherwise you wont get a connection.

mcat · 03-10-2007

Thanks Dan, great answer. My problem is that I don't have access to a trickle charger (or anywhere to plug one in) so I will have to go for a donor vehicle (my other car).

1. You refer to looking at the battery voltage. Is there a meter or indicator for this on the car? One of the menu options?

2. If there is, then I wont I have to switch on the electronics to get to it while connected to the donor vehicle?

3. I have 3 options (listed in terms of what I think the wait time would be):-

- Buy some jump leads and do it myself
- Call TCS (the Swiss touring club breakdown service which I pay a $100 per year for)
- Call Mercedes 24 hr assistance which is suppose to come with the car.

Which would you recommend?

Quote:

Originally Posted by DansSlk

OK from the top.

1- Do not jump start the car whatever you do worst case is you have to start a donor car and connect the jump leads to the battery with the SLK shutdown the donors voltage regulator should provide about 14 volts to the battery acting as a good charger but remember it wont control the voltage at all and you can over-charge the battery so its best to leave it connected for say 5 Min's then disconnect and check the SLK's voltage anything above 11.8 in key position 2 and the car will start if its below that re-connect and wait another 5 Min's. The proper way to do this would be buy a battery charger that will switch to trickle automatically when full.

2- Yeah they will be fine so long as you don't operate anything while charging just leave the car alone and disconnect the charger / donor before doing anything even opening a door.

3- Ynot's covered this one.

4- Yep its stored in EEPROM

5- These are not deep-cycle batteries they are not designed to be drained just to give a jolt of energy to the starter and then be relieved by the alternator a few discharges wont do any noticeable harm but if you plan on leaving the car i would recommend a trickle charger because repeated cycles will cause a noticeable voltage retention issue i.e. it will go flat all the bloody time.

6- Using a trickle charger about 30 Min's to restore the voltage lost in the start and also to get all the fluids up to temp after sitting if your using a donor then prob nearer an hour / hour and a half to get it back to full charge these alternators are designed for low parasitic drag not high performance.

7- Not really mate no as i say don't activate any of the electronics while charging and make sure the charging source is disconnected before powering up the car and if your using a trickle charger use the power terminals provided not the battery the car should accept the charger on those points OK but for a donor connect directly to the battery for the damping effect, again for donors standard stuff connect the leads to its battery then start it then connect the leads to the SLK and remove them before shutting down the donor otherwise you will be draining both battery's starting the donor for the charger connect the lines then connect it to mains power after.

The charge points are the positive under the red cover on the pre-fuse box near the electronics box under the hood and on the chassis to the left of the box you will see a few different harnesses joining up to the metal under the bolt you will see some un-lacquered metal on the connectors hook up the chargers negative to them otherwise you wont get a connection.

DansSlk · 03-10-2007

Buy some leads and do it yourself simple option and you then have the leads should you need them again for any reason.

To get around the electronics problem you have 2 choices buy a multimeter and test the voltage on the battery or charge the car for about 5 Min's then disconnect the leads and open up the SLK then turn the key into position 1 and check the display is showing the total mileage screen then turn the key back to off and back to 1 again once its in 1 very quickly press the R button 3 times and it will show the voltmeter in the display once you have that turn the key into pos 2 and check what it reads.

Above 11.8 then because it is disconnected from the donor start the car immediately and do not shut it off until after you take it for a drive if its below 11.8 then shut it all down give it about a minute and then hook up the donor again.

Just start and stop the donors engine when it is disconnected from the SLK to avoid drain on its battery by the donor.

Because you are using a donor car remember to hook up at the SLK's battery not its charging points.

MB assistance will typically just send a local company for stuff like this and i have seen cars damaged from them using starter packs on the car and i would imagine its the same for most companies.

So much easier to get leads and do it yourself.

Hope this helps mate.

03-09-2007	#1 (permalink)
mcat Founding Member #3 Join Date: Jun 2006 Location: Switzerland & UK Vehicle: 2006 SLK350 MT LHD & 2009 SLK350 7G RHD Posts: 274 Country: Thanks: 1 Thanked 4 Times in 4 Posts	Flat Battery - what to do? My SLK has been parked up for the last couple of months and now the battery is flat. I tried it about 4 weeks ago before going on holiday to Australia and it worked fine. Now I am back it is completely dead. I guess it was too much to hope for. Lots of questions ... 1. Is it a case of a simple jump start to get it going? Anything I need to watch out for? 2. Will all the electronics still work fine? 3. I have the roof module fitted. Any issues getting this going again? 4. Will my service interval clock still read correctly? 5. Have I done damage to my battery by letting it drain like this? 6. How long will I have to drive around to get it fully changed again? 7. Anything else I need to be aware of? Thanks in advance

03-09-2007	#3 (permalink)
Ynot Founding Member Join Date: Jun 2006 Location: Colorado Vehicle: 06' MBZ SLK Posts: 2,795 Country: Thanks: 135 Thanked 35 Times in 30 Posts	That's happened to a handful of members already, no need to worry about it. I'm one of them. I have a battery charger, I let it charged overnight and started up the next morning, got the "roof error, visit workshop", unplug the battery for 10 minutes, and the error went away, off I went, drove around town for 15 minutes and it started just fine the next morning. It's been a few weeks, everything is fine. __________________ 06' SLK 350, Iridium/Ash all pkgs. 6-spd, 19" DCR. To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts.

03-09-2007	#4 (permalink)
DansSlk Dude Join Date: Jun 2006 Location: Wales Vehicle: 05 B55S (Brabus 6.1 S) Posts: 6,752 Country: Thanks: 96 Thanked 221 Times in 173 Posts	OK from the top. 1- Do not jump start the car whatever you do worst case is you have to start a donor car and connect the jump leads to the battery with the SLK shutdown the donors voltage regulator should provide about 14 volts to the battery acting as a good charger but remember it wont control the voltage at all and you can over-charge the battery so its best to leave it connected for say 5 Min's then disconnect and check the SLK's voltage anything above 11.8 in key position 2 and the car will start if its below that re-connect and wait another 5 Min's. The proper way to do this would be buy a battery charger that will switch to trickle automatically when full. 2- Yeah they will be fine so long as you don't operate anything while charging just leave the car alone and disconnect the charger / donor before doing anything even opening a door. 3- Ynot's covered this one. 4- Yep its stored in EEPROM 5- These are not deep-cycle batteries they are not designed to be drained just to give a jolt of energy to the starter and then be relieved by the alternator a few discharges wont do any noticeable harm but if you plan on leaving the car i would recommend a trickle charger because repeated cycles will cause a noticeable voltage retention issue i.e. it will go flat all the bloody time. 6- Using a trickle charger about 30 Min's to restore the voltage lost in the start and also to get all the fluids up to temp after sitting if your using a donor then prob nearer an hour / hour and a half to get it back to full charge these alternators are designed for low parasitic drag not high performance. 7- Not really mate no as i say don't activate any of the electronics while charging and make sure the charging source is disconnected before powering up the car and if your using a trickle charger use the power terminals provided not the battery the car should accept the charger on those points OK but for a donor connect directly to the battery for the damping effect, again for donors standard stuff connect the leads to its battery then start it then connect the leads to the SLK and remove them before shutting down the donor otherwise you will be draining both battery's starting the donor for the charger connect the lines then connect it to mains power after. The charge points are the positive under the red cover on the pre-fuse box near the electronics box under the hood and on the chassis to the left of the box you will see a few different harnesses joining up to the metal under the bolt you will see some un-lacquered metal on the connectors hook up the chargers negative to them otherwise you wont get a connection. __________________ One thing you will learn with German cars - If it's simple it ain't happening.

03-10-2007	#6 (permalink)
DansSlk Dude Join Date: Jun 2006 Location: Wales Vehicle: 05 B55S (Brabus 6.1 S) Posts: 6,752 Country: Thanks: 96 Thanked 221 Times in 173 Posts	Buy some leads and do it yourself simple option and you then have the leads should you need them again for any reason. To get around the electronics problem you have 2 choices buy a multimeter and test the voltage on the battery or charge the car for about 5 Min's then disconnect the leads and open up the SLK then turn the key into position 1 and check the display is showing the total mileage screen then turn the key back to off and back to 1 again once its in 1 very quickly press the R button 3 times and it will show the voltmeter in the display once you have that turn the key into pos 2 and check what it reads. Above 11.8 then because it is disconnected from the donor start the car immediately and do not shut it off until after you take it for a drive if its below 11.8 then shut it all down give it about a minute and then hook up the donor again. Just start and stop the donors engine when it is disconnected from the SLK to avoid drain on its battery by the donor. Because you are using a donor car remember to hook up at the SLK's battery not its charging points. MB assistance will typically just send a local company for stuff like this and i have seen cars damaged from them using starter packs on the car and i would imagine its the same for most companies. So much easier to get leads and do it yourself. Hope this helps mate. __________________ One thing you will learn with German cars - If it's simple it ain't happening.

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03-09-2007	#2 (permalink)
Tslick Elite SLK World Member Join Date: Aug 2006 Location: Long Beach, Ca Vehicle: SLK32 AMG Posts: 1,326 Country: Thanks: 74 Thanked 56 Times in 29 Posts	Bumping this back to the top. There are precautions to take into consideration. Others like Dan would know the proper way to recharge the battery, let alone jump starting.

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