W211 OM642 Lead acid Battery problem

[wilko50]

Hi to you all. This is regarding the main battery in the boot ! I just want to share something that I experienced with my car so you don't have to make the same mistake. My 2005 E Class CDI, (OM642) was suffering from low voltage although the battery I got from Tanya was only a year old. It was reading 11.9 volts in the morning, would start, but all sorts of odd things were happening like the alarm would go off unlocking it, one the the door modules packed up. Also kept getting "Convenience features not available" message even after a long drive, and the heater stopped working.

I did some research and found that only AGM batteries should be placed in these cars, the lead acid type get wrecked by the powerful electrical systems in these vehicles and do not cope well. I looked everywhere for the best deal on a AGM and found Mercedes main dealer to be the best , and they were £40.00 cheaper then Halfords for a Varta , it cost me £200.00 including VAT.

I installed it and all the problems disappeared within a few days without replacing or repairing anything. Resting volts in the morning are now 12.6 to 12.7. For a long time with the lead acid battery I thought I had a power drain from a bad module ( like the door) but that was not the case. The car is now problem free regarding the electrics and it has made a huge difference. I was not aware that lead acid batteries are not suitable for these cars as other people may not be. Many of you will already know but some wont so I hope I have helped.

 

[ambjoinery]

Hi to you all. This is regarding the main battery in the boot ! I just want to share something that I experienced with my car so you don't have to make the same mistake. My 2005 E Class CDI, (OM642) was suffering from low voltage although the battery I got from Tanya was only a year old. It was reading 11.9 volts in the morning, would start, but all sorts of odd things were happening like the alarm would go off unlocking it, one the the door modules packed up. Also kept getting "Convenience features not available" message even after a long drive, and the heater stopped working.

I did some research and found that only AGM batteries should be placed in these cars, the lead acid type get wrecked by the powerful electrical systems in these vehicles and do not cope well. I looked everywhere for the best deal on a AGM and found Mercedes main dealer to be the best , and they were £40.00 cheaper then Halfords for a Varta , it cost me £200.00 including VAT.

I installed it and all the problems disappeared within a few days without replacing or repairing anything. Resting volts in the morning are now 12.6 to 12.7. For a long time with the lead acid battery I thought I had a power drain from a bad module ( like the door) but that was not the case. The car is now problem free regarding the electrics and it has made a huge difference. I was not aware that lead acid batteries are not suitable for these cars as other people may not be. Many of you will already know but some wont so I hope I have helped.

Mine is still on original mb battery wk26 2011 stamped on battery post. Car is parked in garage mostly all wk , mainly wk end use. I can't believe it's lasted this long, I've owned Car 7 years!

 

[BTB 500]

The battery in our Vito (which also has the OM642) is hidden away under the passenger seat ... it's the original one from 2007 so I assume it's lead/acid, but I've never looked!

 

[wilko50]

Mine is still on original mb battery wk26 2011 stamped on battery post. Car is parked in garage mostly all wk , mainly wk end use. I can't believe it's lasted this long, I've owned Car 7 years!

That's amazing , yes being in a garage probably helps hugely, mine is on a street. That's a rare and desirable Merc you have

 

[wilko50]

The battery in our Vito (which also has the OM642) is hidden away under the passenger seat ... it's the original one from 2007 so I assume it's lead/acid, but I've never looked!

That is incredible. I have had me car 11 years now and cant see the point of changing it because I still love it. I am on my third big battery though . I bet your Vito has the AGM Mercedes Varta. It believe that's what they were fitted with back then , even my car which is 2005 had the AGM from factory.

 

[BTB 500]

That is incredible. I have had me car 11 years now and cant see the point of changing it because I still love it. I am on my third big battery though . I bet your Vito has the AGM Mercedes Varta. It believe that's what they were fitted with back then , even my car which is 2005 had the AGM from factory.

The battery in my SL is even older - that was fitted in 2004. But that car is always hooked up to a maintenance charger when not being driven, so doesn't count

 

[wilko50]

The battery in my SL is even older - that was fitted in 2004. But that car is always hooked up to a maintenance charger when not being driven, so doesn't count

Incredible. I just got an AA solar trickle charger for mine because it sits during the week. I checked the resting volts today and it's 12.8. I am hoping that mine may follow yours if I look after it

 

[Plopy]

My Rear Battery in my W221, is the Original 14 years old and still going! the car only has 40k mileage, so the Battery hasn't had that much of an active life. But the car has always been serviced by Mercedes, and now a very good indie. When I check the Standing Voltage in the morning, it lies between 12.1-12.4 volts. I am soon going to replace it (although I feel pained to do so) and will use a genuine MB one from the dealers again.
My other Car (which I sold) was an W204 with 163k miles on it, same Batteries, and Clutch at 10 years old.

 

[wilko50]

My Rear Battery in my W221, is the Original 14 years old and still going! the car only has 40k mileage, so the Battery hasn't had that much of an active life. But the car has always been serviced by Mercedes, and now a very good indie. When I check the Standing Voltage in the morning, it lies between 12.1-12.4 volts. I am soon going to replace it (although I feel pained to do so) and will use a genuine MB one from the dealers again.
My other Car (which I sold) was an W204 with 163k miles on it, same Batteries, and Clutch at 10 years old.

That is fantastic,also considering the low mileage. My car before my Mercedes was a VW Passat. I had that 10 year's and never changed the battery. The W221 is my favourite S class and in my opinion the best looking along with the W126. I would like to get a W221 and some point

 

[johnsco]

I did some research and found that only AGM batteries should be placed in these cars, the lead acid type get wrecked by the powerful electrical systems in these vehicles and do not cope well.

I'm sorry wilko50, but I don't agree.
I've got a lead acid battery in my W211 E280 cdi Sports Estate, which I have owned for around 9 years and used as my work-horse.
There is nothing special about the "powerful electrical systems" in these cars, and the battery has not been "wrecked" and has given excellent service and continues to do so.
Battery voltage in these cars is critical to their reliable performance.
11.9 volts in the morning is not good enough.
It's not surprising that there were problems as described in post #1.

 

[E55BOF]

I'm sorry wilko50, but I don't agree.
I've got a lead acid battery in my W211 E280 cdi Sports Estate, which I have owned for around 9 years and used as my work-horse.
There is nothing special about the "powerful electrical systems" in these cars, and the battery has not been "wrecked" and has given excellent service and continues to do so.
Battery voltage in these cars is critical to their reliable performance.
11.9 volts in the morning is not good enough.
It's not surprising that there were problems as described in post #1.

The OPs car came with an AGM battery from new; it was replaced with a conventional lead/acid battery; a year later the lead/acid battery was dying; it was replaced with an AGM battery, which has solved the problem. Why do you think that might be?

Conventional lead/acid batteries do not generally last as long as AGM batteries. AGM Batteries cost more than lead/acid because they are copnstructed differently, and because they perform better, and almost invariably last longer, than lead/acid batteries. This better performance is needed for the higher electrical demands in more modern cars with complex electrical systems, and the charging voltages and parameters are not the same as for lead acid batteries either. Using a lead/acid instead of an OE AGM battery usually means that it doesn't last long.

Some cheapskate has replaced the OE AGM battery in your car with a conventional lead/acid battery, and you've been iuncredibly lucky it's lasted so long. Either that, or you actually have an AGM battery anyway...