Question from a client of mine
Thread Starter
Newbie
Joined: Aug 2019
Posts: 12
Likes: 0
C300 4matic
Question from a client of mine
Hey all,
i am new to this board but am really thankful for the kindness all have shown me. one year anniversary on my c300 is coming up.
However, i am a allstate agent and client of mine has a 2008 c63 amg. he is asking why the battery cuts out every few days? he buys a new one it cuts out within a week? does anyone what this can mean? i told him i would ask on here. Thank you very much in advance for any insight.
i am new to this board but am really thankful for the kindness all have shown me. one year anniversary on my c300 is coming up.
However, i am a allstate agent and client of mine has a 2008 c63 amg. he is asking why the battery cuts out every few days? he buys a new one it cuts out within a week? does anyone what this can mean? i told him i would ask on here. Thank you very much in advance for any insight.
Super Member
Joined: Jun 2017
Posts: 608
Likes: 107
From: Western NC
2009 MB C300 Sport 4matic
With the car off, key out wait 30 minutes so all the modules time out, then disconnect the battery ground cable and connect a multimeter between the bat neg post and the neg cable. With multimeter set to millivolts, should not see a volt draw greater than 20-30 mvolts...greater means some component is "active" .... then follows the rather tedious job of removing every fuse one by one to hopefully locate the source. You have engine compartment fuses and trunk fuse boxes, perhaps an interior cabin one (see Owner's Manual). A dead alternator/rectifier will drain a battery if the car is run often, not left unused. The multimeter connected to the battery pos and neg post at idle should read 13.9v - 14.3v, lower suggest a weak alternator. Other posts in Forums have pointed towards trunk/glove box lights that fail to go off.
Thread Starter
Newbie
Joined: Aug 2019
Posts: 12
Likes: 0
C300 4matic
With the car off, key out wait 30 minutes so all the modules time out, then disconnect the battery ground cable and connect a multimeter between the bat neg post and the neg cable. With multimeter set to millivolts, should not see a volt draw greater than 20-30 mvolts...greater means some component is "active" .... then follows the rather tedious job of removing every fuse one by one to hopefully locate the source. You have engine compartment fuses and trunk fuse boxes, perhaps an interior cabin one (see Owner's Manual). A dead alternator/rectifier will drain a battery if the car is run often, not left unused. The multimeter connected to the battery pos and neg post at idle should read 13.9v - 14.3v, lower suggest a weak alternator. Other posts in Forums have pointed towards trunk/glove box lights that fail to go off.
Junior Member
Joined: Dec 2020
Posts: 52
Likes: 4
From: Southern Tier, NY
2013 C300 4Matic Sport / 2003 SLK32 AMG
In older R170's, the alarm caused a serious battery drain, thus killing off batteries. Most have disconnected and done away with the alarm...could be something to look at.
