Which car battery for my w220

[shorif2000]

When battery was flat it the 2nd click initially turned on electrics but it wouldn't turn over. Pumping gas didnt help, after i tried again, inserting the key, it did not even turn anything on. Key would turn. After the full charge it seems to be all well other than what i mentioned above with the windows.

I did have to pump gas once when i turned it 1st time. Drove around for hour and half with no problems.

Also i checked voltage on the climate control. N.24 showed 13.4 to 13.9 very rarely hit 14. Would that be problem? Something to do with alternator but didn't quite understand it

Current battery has been in here for 3 years since i bought it from Previous owner. Funnily it never went flat in winter when i dont drive it for 2 weeks but in summer it went flat when i haven't driven for a month. Current battery is not AGM took me 2 days to charge it with ctek.

I have had issues with heating not being powerfull sometimes. Even had the heating unit control replaced last year

 

[steveskeggy]

Pumping the throttle does naff all with fuel injection, when cars had carburettors, the car had a device that squirted fuel into the throttle every time you pressed the accelerator, doing this when you were turning the engine over made the fuel mixture even richer than just using the choke (remember those?).
These days the ECU does all that for you, all you are doing when you pump the throttle is opening the butterfly flap and closing it,

13.4 to 13.9 is bang on for voltage when the engine is running, you can pretty much guarantee your alternator is working OK.
To be honest, in my experience with my S55, 3 years is a good life for one of these.
I have had batteries that died after six months, wont go to kwikfit again!

That you can turn the key when the battery is charged, is a bit of a relief, it means all the pre-start requirements have been reached (All the expensive stuff is working!), if you turn the key to start, and nothing happens, it can mean that the battery has a low current (Usually have the clacking noise and dashboard flashing).
It can also mean the starter motor is lunched, but usually the starter will die after a length of time, going slower and slower, not often it just dies straight away (and when it does start, if it spins normally, it most likely is not the motor).

Thirdly, it can mean there is a faulty relay, which is in the right hand SAM under the bonnet (The fuse diagram incorrectly lists this as Choke, but it is the relay for the low tension side of the starter).

In your case, yes its looking likely to be the battery.
Garages used to do what was called a drop test, it used a meter to more or less short the battery out, and depending how fast the current dropped, they could tell if the battery was had it.

Please remember, the starting proceedure for the engine has more to do with the current coming from the battery than the voltage, you can have a battery putting out 12v, but wont start the car because it is putting out low current.

Two more things.
Its up to you if you want to go AGM or Lead Acid, I cant really say any more than MB recommend AGM, I dont have any experience with AGM, so probably best to do a bit of research first.
Bigger is not always better, You may think that getting a high A/H battery would be best, however this is not always the case, if you get a higher rated battery than standard, the alternator will have to work harder to charge it up, and in some cases it will not be able to charge it up, shortening the lifetime of the alternator, and probably the battery.
The standard battery is rated as 95A/H, I wouldnt go over 100A/H.

 

[shorif2000]

Thanks

 

[Atavus]

I would only use an AGM battery on a car that’s made to charge one correctly. I understand some people have done this, but I wouldn’t.

 

[shorif2000]

I noticed another thing today. The suspension does not seem to go back down once i take key out and lock the car. The ride height stays same.

Its use to go down once key is out and locked and it use to rise up when i unlock and put key in. What is normal?

 

[alabbasi]

You can use a scanner or the SDS to set which battery is being used so that the car will charge appropriately. 3 years for a Battery in the UK, mounted in the boot does not seem like a long time. I get that kind of life out of a battery in Texas, I'd expect a lot better performance in milder weather.