Mercedes SLK World banner

Status
Not open for further replies.
1 - 6 of 6 Posts

·
Super Moderator CA 2012 SLK55 AMG w/P30
Joined
·
13,319 Posts
Discussion Starter #1
Facts: my battery reading AT THE REMOTE posts is ~ 12.45-12.54V after sitting for 24 hr (no load ammeter reading, reading at the "bolt" and the remote red access point, not directly off the battery posts).

I'm assuming that the reading at the remote posts is lower than direct but by how much? I've read this 12.45V reading is around 75% charge (came off a 2 hr run yesterday and just sat for 24 hr then took the reading).

Searched here and elsewhere and general observation is replace at 12.4 V or so but this is not definitive.

Battery is original (5 yr old). I always keep it on a BT but this is not always possible is why I ask:

Time for a new one?
 

·
Administrator 2009 SLK 55 AMG/Founding Member 2006
Joined
·
96,615 Posts
Replace at 12.4? get out of town!
My morning reading before starting car is usually 12.3
alternator takes it to 14.4
I charge once a week.
Len, go have a beer and worry about something else :D
 

·
Super Moderator CA 2012 SLK55 AMG w/P30
Joined
·
13,319 Posts
Discussion Starter #3
You put my mind at rest :grin: Tks for the input.
 

·
Registered 2005 SLK55 AMG
Joined
·
1,697 Posts
^ Take the car to an auto store and have the battery stress tested. Then your mind can be at rest. Once they start to go, they can be unpredictable under load, and have very little reserve if you've been driving with all accessories on ( but that's more of a winter problem obviously).
 

·
Super Moderator CA 2012 SLK55 AMG w/P30
Joined
·
13,319 Posts
Discussion Starter #5
Len, go have a beer and worry about something else :D
At servicing today, had it tested: A OK.

I asked about "load test" rather than just ammeter. Mech said that if a load test was done while the battery is in the car, the electronics would fry.

His tester used some kind of algorithm to test.

Just a follow up :wink:
 

·
Registered 2005 SLK55 AMG
Joined
·
1,697 Posts
^ Yes, I should have been more specific. Modern electronic testing machines 'stress' test the battery by emitting a high frequency ac to the battery to measure internal conductance and use algorithms which accurately determine the internal condition of the battery - nothing like the crude old 'dead short' load testers, but I'm not sure if they would damage the electronics. Mine was tested at a Bosch service center with Bosch testing equipment.
 
1 - 6 of 6 Posts
Status
Not open for further replies.
Top