CLS left for 2 days and now dead as a dodo

[Trickythemerc]

Just for my own peace of mind when it comes to battery issues after trying to convince a Fiat professional dealer that the battery on a two month old van could be dead, I bought a Topdon BT300P battery tester.
The battery on the Ducato kept failing, so Fiat changed the starter motor ? Then it was my driver leaving his Tom Tom on when making a delivery, next up was the lights being left on in the load area ? They had it for two days and charged the battery overnight to 75% apparently that is how battery chargers work ? The alternator will put the other 25% in "Honest Guv"
So I put the Topdon on and did a full test on battery/charging system/CCA Etc. Then took the printout in to the service manager, He looked at it and said Oh that's clever bit of kit.

 

[Petrol Pete]

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[philnewmerc]

Well I need the car reliable for tomorrow so gone ahead and bought a beefy Varta with a little more capacity than standard:

Varta Silver 019 Car Battery - 5 Year Guarantee | Euro Car Parts

Varta Silver 019 Car Battery - 5 Year Guarantee at the lowest UK prices from Euro Car Parts UK’s No.1 for Car Accessories, Car Styling & Car Care. Buy today Online, In store or by Phone + Branches Nationwide – Next Day UK Free Delivery.

www.eurocarparts.com

Ideally I would have got the old one checked but no time to find a place to do it. If it turns out it was a parasitic drain then I'll have a bargain half life varta for sale on ebay (no postage ). Last time I had a similar issue was with my clk500 and after being told the battery was fine by the garage I eventually took it to mercedes who diagnosed a new battery for 400 quid (and no parasitic drain)... From that experience I'm gambling on new battery this time but I will of course update (ie moan like feck ) if this isn't the case.

Thanks very much for the advice all

 

[Bobby Dazzler]

Good points. So was it a drain on yours or not?

One thing that does make me suspicious it may not be the battery (or weak battery and some other issue) is it was 100000% dead after just 2 days and I've left it a week before now. But on the other hand the resting battery voltage is just under 12.5 so not in rude health and as said its been pressed into short trips in the past couple of months just as the temps plummeted. The breakdown chap tested the alternator and said it was charging. How can i check, just see if it's at >14v i presume?

Thanks again

You’ll need to charge it or go on a verrrrrry long trip to charge it more than that. Get it on a charger, you might be surprised.

 

[clk320x]

I didn’t know you drove an EV Phil?

Only pulling your leg. Hope you get it sorted soon.

 

[ChrisPDuck]

In addition to its output voltage, another check to do on the alternator would be the diode pack. A faulty diode can cause a continuous heavy drain on the battery. Such a drain will not show up on any parasitic drain testing in the fuse boxes.

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I also have experience of a faulty voltage regulator causing a significant continuous drain - enough to flatten the battery after a day or two. I suspected a faulty diode, but when I took it to be refurbed they said the diodes were ok. I asked them to change the regulator as a precaution (since it was a major effort to get the alternator out), and that solved the drain.

 

[philnewmerc]

I'm going to monitor the battery I took out over a few days and see what voltage it retains. Then use the table AMGeed provided to see if it's healthy. Or I suppose I could just take it to a shop when I have time and see if they'll test it.

One other thing of note was the battery in the car was an AGM but the new one recommended by Varta was not... Can't imagine that makes amy different tho? The new one doesn't seem to have a vent which puzzles me slightly.

Oh and there was no date stamp on the terminals that I could see but maybe it had been scraped off at some point.

 

[Smiley]

Good points. So was it a drain on yours or not?

One thing that does make me suspicious it may not be the battery (or weak battery and some other issue) is it was 100000% dead after just 2 days and I've left it a week before now. But on the other hand the resting battery voltage is just under 12.5 so not in rude health and as said its been pressed into short trips in the past couple of months just as the temps plummeted. The breakdown chap tested the alternator and said it was charging. How can i check, just see if it's at >14v i presume?

Thanks again

I checked for current drain after charging the batteries back up but could not find anything. Has not happened again and that was a year ago.
Re the alternator check - yes 14.3 volts when running.
Funny thing is that a friend with a 211 had exactly the same thing happen as a one off complete battery drain - been fine ever since.

 

[Smiley]

Not sure why anyone would go to the additional cost of putting a AGM battery in? Don't see how that could cause the problem you have though. I think that cars with AGM batteries (to support the stop start functionality) also have different alternator output rates - not that it would have caused your issues.

 

[philnewmerc]

Might have been too hasty?! The battery I took out was a Varta AGM and after a very long run beforre I swapped it it was at 12.7 V (decided to swap it anyway as I went through a complete carry-on with my CLK that turned out to be just the battery when even the local garage said it was ok). Anyway, day 2 and the voltage is 12.6 V on the old battery. According to the battery health table above that means it's healthy . Reasons I decided to swap are, though I was told it was newish I have no idea as cannot see a date stamp, it is an AGM type but lead acid is spec'd from new (According to Varta... not sure if that's correct? No idea if that makes a difference, I would presume not but I've presumed too much before), and if the car does still go flat I'll know for certain that I need to take it to Mercedes to be sorted. I'm going to monitor the old battery for a couple of weeks and if it holds voltage I'll try and sell it (amazingly there are 350 used Varta batteries on Ebay!)... but I hope it looses voltage as I'll feel better about the 195 quid I spent yesterday

Hang on Yuasa say "OE BATTERY IS AGM. ONLY REPLACE WITH AGM BATTERY"

Halfords also says AGM

Tanya say AGM

But Varta themselves say this one
600 402 083 | Varta Automotive

Hmmmm, why would Varta direct, the OEM supplier, say non-AGM if it wasn't right? Anyone know how to check for sure what battery is right?

 

[philnewmerc]

ooof, I feel a bill sick. I was in a hurry to buy yesterday to have a relibale car for the week so used Eurocarpats. I bought this for £195

Varta Silver 019 Car Battery - 5 Year Guarantee | Euro Car Parts

Varta Silver 019 Car Battery - 5 Year Guarantee at the lowest UK prices from Euro Car Parts UK’s No.1 for Car Accessories, Car Styling & Car Care. Buy today Online, In store or by Phone + Branches Nationwide – Next Day UK Free Delivery.

www.eurocarparts.com

But it is on Tanya for £135.

Varta 019 (H3) Silver Dynamic Car Battery 12V 100Ah - 600 402 083

H3 VARTA Silver Dynamic Car Battery <i>Innovation with Purpose, Premium Experience, Powerful History</i> VARTA was founded in 1887 Germany, and was established fully in 1904 by delivering the first electric vehicle battery, famously driven by Thomas Edison. Soon after, VARTA delivers the first...

www.tayna.co.uk

 

[sautah]

I have a non stop start 2011 E class 250 CDI That had a Mercedes branded AGM battery. It died and I replaced with an AGM VARTA from Tanya

 

[Stratman]

Is it a real AGM or does it just have AGM badges

 

[philnewmerc]

Phoned Mercedes Ncl but they won't tell me, only that it is £220

 

[Bobby Dazzler]

Phoned Mercedes Ncl but they won't tell me, only that it is £220

Phone another dealer. When they tell you the price say “Ooof that is more expensive than I thought it would be, is that for AGM or basic lead acid??”

I think it’s very likely to be an AGM on your car. Whilst AGM is lead acid with glass matting, the charging profile is different. At best you wonnt get the best out of your investment. At worst you will have to replace it prematurely.

Finally ECP are hellishly expensive however they take returns without quibble. I bought a couple of leisure batteries from them for that reason. Returning a faulty battery to Tayna makes moon landings look easy.

 

[philnewmerc]

Phone another dealer. When they tell you the price say “Ooof that is more expensive than I thought it would be, is that for AGM or basic lead acid??”

I think it’s very likely to be an AGM on your car. Whilst AGM is lead acid with glass matting, the charging profile is different. At best you wonnt get the best out of your investment. At worst you will have to replace it prematurely.

Finally ECP are hellishly expensive however they take returns without quibble. I bought a couple of leisure batteries from them for that reason. Returning a faulty battery to Tayna makes moon landings look easy.

Good advice, will try that.
But if the car was designed for normal battery wouldn't AGM cause any issues?

 

[Bobby Dazzler]

Good advice, will try that.
But if the car was designed for normal battery wouldn't AGM cause any issues?

The charging profiles are similar but different. so whether switching from AGM to traditional lead acid - or lead acid to AGM - it’s best to bear this in mind. It wouldn’t be dangerous, it would probably just affect the useful life of the battery.

 

[Smiley]

1. If your car does not have stop start then I really doubt it takes an AGM battery.
2. As already said Euro (and GSF for that matter) became expensive (and sometimes very expensive) during covid
3. Tayna (everyone misspells it Tanya) is cheap and fast delivery. But also as already said if you have a warranty issue then stand by to be spending a lot of time and effort dealing with it and be without a battery for up to 10 days (I gave up and bought another locally)
4. There are other local battery suppliers around the country who are almost as cheap as Tayna but don't advertise - google battery supplier and call them, then pick it up - you'll get better after sales service if you need it.
5. If you do have a drain problem with the car you need a good old school mechanic rather than MB main dealer imho. It is a case of methodically checking each circuit but only after the car has had time to "go to sleep"

 

[sautah]

Is it a real AGM or does it just have AGM ba

1. If your car does not have stop start then I really doubt it takes an AGM battery.
2. As already said Euro (and GSF for that matter) became expensive (and sometimes very expensive) during covid
3. Tayna (everyone misspells it Tanya) is cheap and fast delivery. But also as already said if you have a warranty issue then stand by to be spending a lot of time and effort dealing with it and be without a battery for up to 10 days (I gave up and bought another locally)
4. There are other local battery suppliers around the country who are almost as cheap as Tayna but don't advertise - google battery supplier and call them, then pick it up - you'll get better after sales service if you need it.
5. If you do have a drain problem with the car you need a good old school mechanic rather than MB main dealer imho. It is a case of methodically checking each circuit but only after the car has had time to "go to sleep"

As stated my 2011 e class has an AGM battery from the factory. It isn’t stop start. It’s been in there since 2011 and I’ve only just replaced it. With an AGM

 

[FiveAlive]

Likewise, my 2011 E350CDI has an AGM battery and no stop-start. Mercedes switched over to AGM because it had better characteristics than standard lead-acid. It happened that these characteristics were essential for stop-start, but were still of value without it.