Battery goes flat.

[John77]

With the car off, fuse box open, DMM on DC Volts, one probe on one side of the fuse and the other probe on the other side of the same fuse.
Blade fuses have small cut outs in the top that you can connect to with the probes.

Thank you

 

[oigle]

Only 2 options really. Have a Ctek charger connected all the time or disconnect the battery when stored. I disconnect and only issue is recoding my radio when re-connected. On later cars, there are no codes so that eliminates that. I find that 3 weeks is the max I can leave it in normal state. Battery will be quite low but just usable. Once battery has been flattened a few times, it is often stuffed. Best to not allow that to happen.

 

[sonic]

We had a 2010 SLK200K, at the start of Covid the battery was going flat in about 1 to 2 weeks but it was the original battery. The car was hardly being used.
Replaced it no further problems, not bad for a 9.5 year old battery.

 

[davidsl500]

I leave my SLK unlocked in the garage and the battery will drop down to 11.9/12V after 2 weeks of non use from its 12.7/12.8V fully charged norm. I just drop the Maypole charger on it to bring it back to optimum.

 

[Tony Dyson]

The battery is a Exide premium Car battery, so no not a cheapy.

​

The fact that it's an Exide battery tells me it wasn't replaced as an original OEM product, so there are questions that I would feel need to be resolved, firstly, the Exide brand is a goto brand and will match or exceed the performance of any other leading brand of the same specifications and this is I think something you would need to look further into, the following features should match the OEM specs:

1. Physical Size and Configuration, the battery needs to fit into the same space and secure constraints as the original.
2. Chemical Technology, i.e. Flooded, EFB or AGM, the batteries should match the on board charging algorithms for optimum performance.
3. The replacement battery should match or exceed the Ah, and CCA ratings of the original.

Confirm you have the correct battery first, then go from there.

 

[John77]

The fact that it's an Exide battery tells me it wasn't replaced as an original OEM product, so there are questions that I would feel need to be resolved, firstly, the Exide brand is a goto brand and will match or exceed the performance of any other leading brand of the same specifications and this is I think something you would need to look further into, the following features should match the OEM specs:

1. Physical Size and Configuration, the battery needs to fit into the same space and secure constraints as the original.
2. Chemical Technology, i.e. Flooded, EFB or AGM, the batteries should match the on board charging algorithms for optimum performance.
3. The replacement battery should match or exceed the Ah, and CCA ratings of the original.

Confirm you have the correct battery first, then go from there.

Hi thank you. The Ah is 72 and the CCA is 720. The size is slightly bigger than the original.

 

[Tony Dyson]

Hi thank you. The Ah is 72 and the CCA is 720. The size is slightly bigger than the original.

And did you confirm what the OEM spec is from MB for comparison?

 

[flowrider]

Is it an AGM battery?

 

[mioba]

Is it an AGM battery?

doubt it being a 2006 car

 

[flowrider]

doubt it being a 2006 car

My 2004 SL has an AGM battery, all R230's from 2001 have AGM batteries.

 

[John77]

Thank you

 

[John77]

So fully charged battery and I have not used the car in 4 days and the battery was dead. Totally dead. Would not even open the locks and when I went to charge it with my all singing battery charger, it just flashed fault and would not charge. So out came my old 1960's charger and it started to charge and after an hour put it on my other charger and now it charged. Left it on for 2 days and now put back on the car.

Locked the car but left the bonnet open and left it for at least half an hour and then did the test OF ONE fuse box. I will test the other when I have opened the door, fuse box and left again for at least half an hour. Any way this is what I found. I only followed what to do, as I have not done this before. Here are the results with photos. Are these 3 fuse tests a problem? See photos.

2nd fuse box in the car. Fuse 21 soft Top 2.5
fuse 30 instrument cluster 1.6

 

[Tony Dyson]

That level of PD across the tested fuselinks would suggest a drain of around:

1. c1.3A through a 10A fuselink​
2. c3.0A through a 20A fuselink​
3. c7.0A through a 40A fuselink​

Assuming you didn’t change the scale from 200 mV, and you need to take better photo’s!

 

[Craiglxviii]

Any of those current drains will kill a battery in short order…

 

[John77]

Any of those current drains will kill a battery in short order…

Yes 4 day and dead as a dodo. Still need to check the back fuse box.

OK so the fuses were
21 soft Top 2.5
30 Instrument Cluster 1.6
others showing drain were
60 ABS/ESP
62 Diag Socket
63 Low Beam
64 Radio/Nav

Not checked the back box yet.

 

[Craiglxviii]

Yes 4 day and dead as a dodo. Still need to check the back fuse box.

OK so the fuses were
21 soft Top 2.5
30 Instrument Cluster 1.6
others showing drain were
60 ABS/ESP
62 Diag Socket
63 Low Beam
64 Radio/Nav

Not checked the back box yet.

Check the alternator and specifically the voltage regulator.

 

[NJS5]

My solution is to connect to a decent battery conditioner when the car is parked, and when away from home & the car is likely to be unused for a few days pack my NOCO portable lithium jump starter in case it's needed.

NJSS

 

[John77]

My solution is to connect to a decent battery conditioner when the car is parked, and when away from home & the car is likely to be unused for a few days pack my NOCO portable lithium jump starter in case it's needed.

NJSS

you wouldn't expect to need to do that with a car. My Eclass will last for weeks when we go abroad, without being recharged. Surely this is a fault that can be fixed?

 

[John77]

Check the alternator and specifically the voltage regulator.

Thank you and do this how exactly, as I am not that knowledgeable on electrics.

 

[Doug1234]

Fuse 62 diagnostic socket and fuse 64 radio / nav....
Diagnostic socket not fitted with one of those bluetooth readers for monitoring engine is it ? as these will quickly kill a battery as it will be constantly on and with the radio/ nav is that also possibly searching to pair with a phone ?.