Battery draining?

[greekCL]

Hello guys,

Been having a problem recently with my CL500 ... seems to drain the battery below 9.0V in 3 days ... of sitting.

I have charged the battery on my charger yesterday ... and today the battery was showing 12.8V ... I suppose better than nothing
I have recruited a friend with V/Amperometer and put it on the battery to check drainage ...

Here are the figures, let me know if they seem normal or do I need to dig in more.

Battery is a 100AH

With the aftermarket stereo front but everything switched off
About 200mA (0.2A) drainage

Without the stero front on and everything closed ..boot, bonner, doors .. everything
About 75mA (0.075A) drainage

I am going to park the car from now on without the stereo face on and see if that 0.075A is enough to drain the battery so low.

The car does not do big trips usually ... maybe a 14miles journey 3-4 times a week.

Cheers
Vasilis

 

[BTB 500]

Sounds like your battery has had it. 9.0V is effectively dead (fully discharged is 11.9V).

To lose 100AH in 3 days you'd need a constant current of approx. 1.4 amps, which you are nowhere near.

 

[greekCL]

Whoopps... the company I got the battery from is saying that there is something draining the battery. Hence they will not admit that there is a fault with the battery.

I have removed the headunit face tonight ... I just remembered earlier actually ... that when I was living in London I used to always remove the headunit face.
However since I moved out of London ... due to parking the car off the road stopped taking it off... this is more less when the batteries started getting weaker.

I will monitor and provide an update Thanks Bill.

 

[steve333]

Whoopps... the company I got the battery from is saying that there is something draining the battery. Hence they will not admit that there is a fault with the battery.

I have removed the headunit face tonight ... I just remembered earlier actually ... that when I was living in London I used to always remove the headunit face.
However since I moved out of London ... due to parking the car off the road stopped taking it off... this is more less when the batteries started getting weaker.

I will monitor and provide an update Thanks Bill.

Ask them to give you another battery for a few days on loan to see if that discharges then you will know something is draining it otherwise if all is ok then the original battery supplied is at fault?

 

[cl55 amg]

Can I ask what battery you use? I had the same issue so gave it to a auto electrician where he monitored it for three days and could find no drain. he recommended replacing the battery with a Bosch.

 

[jefrs]

Holding 12.8V is perfect, but discharging to 9.0V is bad.

0.2A should not / cannot drain a battery down to 9.0V in three days

100Ah is 1 A for 100 hours. 72h x 0.2A = 14.4Ah

A car battery is "discharged" at 12.2V so 9.0V is very dead.

Even though you can charge it to the correct 12.8V, is it holding that that charge for long? You need to determine whether it is discharging itself i.e. by measuring off the car for some period after charging, e.g. at one day, two days. three days. A faulty battery can discharge itself.

 

[greekCL]

OK it was the headunit ... once I take off the face.
The car battery can last a whole week between car starts.
I think the battery being a cheap one does not help... but hey it does the job for now.