s211 car dead

[Will]

Your siren is probably duff then, the backup battery is supposed to keep it working if the main battery is disconnected or flat etc.

Could be related to your battery drain - worth checking

 

[Dec]

If the alarm is faulty then it’s best the siren is removed in case it was the cause of the flat battery.

The siren contains the brains of the alarm system. A NEW replacement cost around £100 from an MB dealer.

Guide here… W211 Alarm Siren replacement

Dec

 

[DavidL]

I have managed to open the tailgate and get to the battery. Its reading 4.8v. Genuine OEM part and not quite 3 yrs old. Any idea what the guarantee on these is? Can merc tell from the unit its age?
Just wondered if they might replace it.
Otherwise it looks like a new battery. I can't see that in 2 days, having had no other issues something would kill it that fast. I know modern batteries don't give warning but this is crazy.
I'll get the siren checked too.

 

[MikeInWimbledon]

OK, maybe I've missed something? Why not stick a battery conditioner on it?

Agreed something might have flattened it, but why not recondition it first before chucking it?

And then see if there's some kind of issue with the system

 

[DavidL]

Mike, Its on an accumate as we speak. After 2 hours it had made no difference but its still on there. It'll take a while to recover from 4v!
As you say worth a go but I won't hold my breathe!

 

[AMGeed]

I have found that a very flat battery doesn't respond to a conditioning charger and needs a healthy 6amp charge put into it for a couple of hours before reconnecting the reconditioner.

 

[DavidL]

As per Mr Geed - a couple of hours on an old fashioned battery charger and then over night on the conditioner and I have 11.5v. Enough to set the alarm off and send the dash a bit mad - mainly brakes it seemed concerned about and the clock spinning like a top. Anyway everything ok except the clearly isn't enough to actually start the car, no attempt to spin the starter. So I can't help feeling its a new battery needed?

 

[Will]

I think MB batteries should have 3-years warranty (2 years on most other parts)

They used to have a date stamp, might be on the lead terminals in the format Week:Year (eg 20:14 would be week 20 of 2014)

I’d take it back to them and ask, nothing to lose. They should be able to test it for you too.

If you need a new one don’t buy it from the passenger car dealer, it’s the same (identical) part they use on Sprinters etc, 100Ah from Commercial dealer - last one I bought was £62+VAT - about half what they wanted at my usual parts dealer.

They used to fit AGM batteries for £200+ but I think they stopped using them a few years back. I’ve run a regular lead acid battery in mine now with zero issues, always starts perfectly throughout the winter months and never get any convenience disabled messages either even with sporadic use (eg left a week without use, shorter journeys etc)

 

[DavidL]

week 32 2014 so just over 3 yrs! I'll see if I can reach the commercial people.

 

[Will]

week 32 2014 so just over 3 yrs! I'll see if I can reach the commercial people.

That’s the production date of the battery, the warranty will be based on date of purchase.

It’s almost certainly less than three years old if it was made in the factory on week 32 of 2014 - look for the receipt.

 

[DavidL]

I've got the receipt on a PO invoice from 11/14. But MB have just confirmed a 2 yr guarantee on parts, batteries included.

 

[AMGeed]

^ 2 years is a little mean on an OEM battery.
Even Halfrauds give you 3 years on their own branded batteries.

 

[DavidL]

MB commercial are only £10 less than MB cars and much further away I can find an bosch s5 just cheaper but as MB have one I'll go there I think £150 so not cheap but could be worse.

 

[Will]

MB commercial are only £10 less than MB cars and much further away I can find an bosch s5 just cheaper but as MB have one I'll go there I think £150 so not cheap but could be worse.

Ouch!

I paid less than that for *two* original MB batteries last January!

In fact before that I also bought one for my CLK55, including overnight FedEx or UPS (can’t recall which one) from another MB Commercial dealer and was still well under £100.

I would ask for some discount at least.

 

[Will]

Mercedes-Benz Sprinter Van Battery A000 982 33 08/26 12v 100ah 019 EN760A. | eBay

Last two from there (they may courier - worth asking)

Also used Orwell Truck and Van who did overnight courier.

If no good for you could always be useful for other members!