Do I need to replace my battery?

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Mickc

New Member
Joined
Jun 2, 2020
Messages
9
Location
Preston
Car
E350 coupe
2015 C207 e350 coupe approx 50k miles.
My aircon is functioning erratically. I only had it re-gassed around a month ago, and now most times it blows ice cold, but sometimes it will only blow ambient non-chilled air into the cabin. I had a system diagnosis carried out today, and they found it to be fully operation with no leaks or faults. Also, my ECO start stop hardly ever works, even in warm weather and after a good motorway run. Even when this system is working, and the engine stops at the lights etc, it re-starts again almost immediately. Also, my distance emergency function keeps disabling itself on initial starting - not all the time, but quite often. And lastly, my phone app keeps dinging to say my car is unlocked, even when it isn't. All these issues, which have been happening for about a week, are annoying but not disastrous. But hopefully they aren't leading up to something more troublesome.

Do I need a new main or aux battery? Or both? Both batteries are original MB parts, so presumably neither have ever been swapped (certainly not in my two years of ownership). Is there a sure fire way to tell if one of the batteries is failing? I do run a battery conditioner on my main battery every six weeks or so. If I do need to replace the batteries, can anyone suggest where to get the best prices? Non branded are fine.
Thanks very much!
 
Most fastfits will do a free battery condition test. Then ring around the factors for best price.
 
I would be tempted to buy a good quality battery conditioner before buying a battery. Unless the battery is a write-off it could revive and extend the life of the battery.

Something like a CTEK MXS 5.0 (or equivalent) would be ideal and I’ve picked them up for as little as £50 each. Don’t use it on lithium batteries though.

Even a cheap battery is expensive these days, I would prefer to use a CTEK maintained old quality battery than an un-maintained new cheap battery.
 
I would be tempted to buy a good quality battery conditioner before buying a battery. Unless the battery is a write-off it could revive and extend the life of the battery.

Something like a CTEK MXS 5.0 (or equivalent) would be ideal and I’ve picked them up for as little as £50 each. Don’t use it on lithium batteries though.

Even a cheap battery is expensive these days, I would prefer to use a CTEK maintained old quality battery than an un-maintained new cheap battery.
Hi thanks, I've used a good quality Maypole conditioner every 4-6 weeks for the two years I've owned the car. I think it might have given me an extra year or more, but after 7 years+ I think it's probably time for a new battery anyway. Whether I also need to swap the aux battery in the boot is another question hopefully someone will be able to answer...
 
If you do need to replace your battery, I got a new one from here... Tayna Batteries ,next day and half the price of Eurocarpratz
 
I had a Volvo S40 a few years back which died instantly thanks to a duff battery. No warning lights, no hints that it was about to fail, the car just completely shut down while I was in a queue of traffic. I had to get an expensive tow to my garage, and I was out of action for two days. Hence I'd rather sort this out before things go badly wrong. Both my current batteries look pretty old so I've replaced both with Vartas from Tayna for exactly £200.
I'll fit them both when they arrive tomorrow and then I can stop worrying about conking out.
Ta for all the suggestions.
 
I've used a good quality Maypole conditioner every 4-6 weeks for the two years I've owned the car. I think it might have given me an extra year or more, but after 7 years+ I think it's probably time for a new battery anyway.

The battery in our Vito is 15 years old now (142,000 miles), and has never been on a charger or conditioner. The one in my SL is 18 years old, but that is kept on a maintenance charger (low usage). These are basic lead/acid batteries though ... I suspect modern ones are a bit more fragile! Our 2019 C Class needed a new battery when we bought it at just over a year old - that was an MB demonstrator that I assume had been left standing for some time during the Covid pandemic (it had only done 5,800 miles).
 
2015 C207 e350 coupe approx 50k miles.
My aircon is functioning erratically. I only had it re-gassed around a month ago, and now most times it blows ice cold, but sometimes it will only blow ambient non-chilled air into the cabin. I had a system diagnosis carried out today, and they found it to be fully operation with no leaks or faults. Also, my ECO start stop hardly ever works, even in warm weather and after a good motorway run. Even when this system is working, and the engine stops at the lights etc, it re-starts again almost immediately. Also, my distance emergency function keeps disabling itself on initial starting - not all the time, but quite often. And lastly, my phone app keeps dinging to say my car is unlocked, even when it isn't. All these issues, which have been happening for about a week, are annoying but not disastrous. But hopefully they aren't leading up to something more troublesome.

Do I need a new main or aux battery? Or both? Both batteries are original MB parts, so presumably neither have ever been swapped (certainly not in my two years of ownership). Is there a sure fire way to tell if one of the batteries is failing? I do run a battery conditioner on my main battery every six weeks or so. If I do need to replace the batteries, can anyone suggest where to get the best prices? Non branded are fine.
Thanks very much!
Page 335 of the E Class Driver's Manual says: (edited)
* NOTE Damage to the battery from overvoltage. When charging using a battery charger without a maximum charging voltage, the battery or the on-board electronics may be damaged.
Vehicles with a lithium-ion battery # Only use battery chargers with a maximum charging voltage of 14.4 V.
All other vehicles # Only use battery chargers with a maximum charging voltage of 14.8 V.

I stopped using a no-name Chinese battery conditioner because it finishes the charge at 15.4v. My E Class has an AGM (Absorbent Glass Mat) battery So I bought a NOCO Genius 5UK which can also be used on Lithium batteries (unlike the CTEK) and has a specific button setting for AGM, whereas the CTEK determines which type of battery you have. See a comparison at NOCO Genius 5 UK vs. CTEK MXS5.0 - Car Battery Geek

I have the same problem with stop-start not working, even on a long run. The dealership says this is relatively normal and depends on battery condition, use of electronics on the car etc. But I got this on a long run of daylight driving with only the aircon on.
 
These folks are also highly competetive and free delivery....

 
I have the same problem with stop-start not working, even on a long run. The dealership says this is relatively normal and depends on battery condition, use of electronics on the car etc. But I got this on a long run of daylight driving with only the aircon on.

That was the only symptom of a battery issue on our W205 (and the Mercedes Me app always reported the battery status as 'partially charged' on the Service menu). Stop/start has worked perfectly since a new battery was fitted 18 months ago.
 
My battery was only running at 11.5 volts with no start stop so i purchased a new one for about £160 online . everything works now the auxiliary battery wasn't changed.
 

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