Main Battery life expectancy?

[Leigh Walker]

Morning all,

I have a 2017 C220d with 53k on the clock. Over the last few days the battery seems to be weak and I was wondering how long these things are supposed to last? I jump started it yesterday and left it ticking over for 10mins then left it over night... I got up this morning (in the snow) and it started fine. Went out to get fuel, upon return to the car the dash was dead but there was just enough juice to start the car..

The car went back to Merc 18months ago as the stop / start system stopped working. I noticed about 3 months ago it had stopped working again (this time, unfortunately outside of warranty)...

BTW battery was pulling over 14Volts when running...

New battery??

Thanks,

Leigh

 

[jimbg]

It is the voltage in the battery you need to check, not the voltage coming from the alternator charge.

Measure the voltage when the car has been left for a while, such as first thing in the morning.

It should read around 12.6 volts for a fully charged battery, 10 minutes idle has probably left you worst off!

I would suggest you put in on charge overnight and go from there.

 

[rorywquin]

^^^^^ what he says & use a quality charger

 

[onefortheroad]

It takes 500 miles apparently to charge a flat battery . Short trips , lights on, fans on , defrosts on . Will all takes its toll even on a new battery. Overnight charge once a month / fortnight in the winter with a smart charger is good sence.

 

[Leigh Walker]

Thanks all..... When I checked yesterday the voltage was 9V with no load on (car off). The confusion was that after jump start, 10mins idling and then overnight in the snow, car started this morning...??

The issue is, the car is just about to go back to Mercedes and I'm loathed to pay out anything unless I really have to.

I'm going to check voltage again now (it's been sat for 2 hours).

 

[EmilysDad]

.....

The issue is, the car is just about to go back to Mercedes and I'm loathed to pay out anything unless I really have to.
.....

Put the car on charge the night before you return it ...

 

[sonic]

Cold weather always finds a weak battery, but I would check you don’t have a current drain when everything is off. As others have said short journeys don’t help, you need to drive about 10 miles to put back into the battery what you have taken out starting it.
As for battery life my E class is almost 10 years old & still has the original battery. I changed the battery on the wife’s. SLK at 9.5 years, the only battery I have ever bought for a Mercedes.

 

[Leigh Walker]

Just checked; off load battery was showing between 12.4 and 12.7 volts and started first turn of the key... ‍

I haven't got the correct charger for the type of battery so I think I'll check again in the morning then take it for a good run (if the snow clears)...

Thanks all....

 

[sonic]

Just checked; off load battery was showing between 12.4 and 12.7 volts and started first turn of the key... ‍

I haven't got the correct charger for the type of battery so I think I'll check again in the morning then take it for a good run (if the snow clears)...

Thanks all....

Get a conditioner/charger, Aldi do good ones at great prices.

 

[Blobcat]

The battery may also be drying out... had a 2018 AGM one that wouldn’t hold a charge. Cells dry, refilled and working again perfectly.

 

[onefortheroad]

The battery may also be drying out... had a 2018 AGM one that wouldn’t hold a charge. Cells dry, refilled and working again perfectly.

This ^^^^ my battery was a 2016 agm . Put a bit deionised water into each cell. Normal battery charger on 4 amps had it fizzing like a good n . Blobcats idea ..