Go Back   MBClub UK - Bringing together Mercedes Enthusiasts > Technical > Electronics
MBClub supports BEN Official Stickers @mbclubuk


Electronics In-Car-Entertainment (ICE), satellite navigation, lighting and wiring

Reply
 
Thread Tools
Old 03-12-2011, 05:40 PM   #1
Hardcore MB Enthusiast
 
greekCL's Avatar
 
Join Date: Jun 2008
Location: Kent
Car: Mercedes 300SL-24 (R129 '92) Lexus GS300 Nav ('98) Mazda RX8 231 ('03) Renault Velsatis 3.5 V6 Initi
Posts: 362
Battery draining?

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
__________________
The faster... the better...
Mercedes 300SL-24 (R129 '92)
BMW 735i Individual M Pack ('00)
Mazda RX8 231 ('03)
Lexus GS300 SE Navigator ('98)
Renault Velsatis Initiale 3.5 V6 ('03)

Previous Cars
Mercedes CL500 (W215 '00)
Lexus IS300 SportCross ('02)
Citroen C5 2.2HDi Exclusive ('02)
Cadillac STS 4.6L ('00)
Toyota Supra N/A SZ '95 model
Smart Passion ForTwo (2003)
Mercedes 200E (W124 1989)
greekCL is offline   Reply With Quote
Old 03-12-2011, 06:13 PM   #2
Hardcore MB Enthusiast
 
BTB 500's Avatar
 
Join Date: Aug 2005
Location: Berkshire
Car: R129 SL500, 639 Vito 120 Dualiner Long, S203 C230 Avantgarde SE Sport
Posts: 14,761
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.
BTB 500 is offline   Reply With Quote
Sponsored Links
Old 03-12-2011, 11:31 PM   #3
Hardcore MB Enthusiast
Threadstarter
 
greekCL's Avatar
 
Join Date: Jun 2008
Location: Kent
Car: Mercedes 300SL-24 (R129 '92) Lexus GS300 Nav ('98) Mazda RX8 231 ('03) Renault Velsatis 3.5 V6 Initi
Posts: 362
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.
greekCL is offline   Reply With Quote
Old 04-12-2011, 08:06 AM   #4
Hardcore MB Enthusiast
 
steve333's Avatar
 
Join Date: Oct 2009
Location: Walton-on-thames
Car: W212 E350cdi sport saloon,r170 slk230k.
Posts: 3,447
Quote:
Originally Posted by greekCL View Post
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?
steve333 is offline   Reply With Quote
Old 04-12-2011, 02:23 PM   #5
Hardcore MB Enthusiast
 
Join Date: May 2009
Location: Manchester
Car: CL55 AMG
Posts: 543
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.
cl55 amg is offline   Reply With Quote
Old 04-12-2011, 03:12 PM   #6
Hardcore MB Enthusiast
 
Join Date: May 2010
Location: Berkshire
Car: S210 E320 Avantgarde '98 full load
Posts: 617
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.
jefrs is offline   Reply With Quote
Old 27-03-2013, 10:28 AM   #7
Hardcore MB Enthusiast
Threadstarter
 
greekCL's Avatar
 
Join Date: Jun 2008
Location: Kent
Car: Mercedes 300SL-24 (R129 '92) Lexus GS300 Nav ('98) Mazda RX8 231 ('03) Renault Velsatis 3.5 V6 Initi
Posts: 362
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.
greekCL is offline   Reply With Quote
Reply

Tags
battery, draining


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools



All times are GMT +1. The time now is 09:35 PM.


MB club UK is A Mercedes Enthusiast club run by enthusiasts for enthusiasts, MBClub UK is in no way affiliated with Mercedes-Benz, DaimlerChrysler or any of their respective trademarks. The posted views of our members are in no way the views of MBClub.co.uk or its owners.
Find us on Google+