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car battery reading 11.8v standing

Joined
Dec 25, 2019
Messages
55
Location
bexley
Car
s55 amg kompressor
Would this be the issue of my central locking taking ages to open in the mornings, even now starting to do do this after a few hours now. Will only open using the keyless card in the mornings, but takes a few pulls of the door handle, the dashboard lights up straight away but doors wont open till they decide to. when running the battery is showing 13.8v to a maximum of 14.2 v. Have ordered a new s5 battery in hope this has been the problem with my central locking not opening after standing.
 
Doubt it tbh. Ive known immobilisers etc throw wobblers with close to death batteries . But those cars wouldnt even turn over due to the battery having no charge.
 
Would this be the issue of my central locking taking ages to open in the mornings, even now starting to do do this after a few hours now. Will only open using the keyless card in the mornings, but takes a few pulls of the door handle, the dashboard lights up straight away but doors wont open till they decide to. when running the battery is showing 13.8v to a maximum of 14.2 v. Have ordered a new s5 battery in hope this has been the problem with my central locking not opening after standing.
Yes most probably, the battery volts at rest should be 12.6-12.8 volts, it may just need charging/topup levels or it has a dead cell.
13.8-14.2 volts while running means the alternator is working correctly.
 
My old w211 display was always around 11.8 v standing . Id charge it through winter using a trickle charger. Even with a £189 varta g14 fitted it never registered 12 volts for very long after an overnight stand.
 
It's harder to interpret rested voltage in a modern car because any significant current draw pulls the voltage down but if the car was truly at rest and drawing negligible current then 11.8 volts indicates that the battery is pretty much flat and certainly no more than 25% charged. If you can't achieve a rested voltage of at least 12.6- 12.8 volts after a fully charging the battery then it's scrap. If that's the case I expect a new battery may resolve the central locking problem.
 
Don't forget as soon as you unlock the car or open a door various systems come alive and that can reduce the voltage.
 
been out all day took the keyless go card with me all good, opening and closing and stop start perfect, just got in so thought I would lock car with remote, kept my keyless card in the rfk pouch so car would not pick up on it, Low and behold would not lock car, checked via camera phone and infra red working, put key in rfk pouch had keyless card in pocket and closed and opened perfect.
 
been out all day took the keyless go card with me all good, opening and closing and stop start perfect, just got in so thought I would lock car with remote, kept my keyless card in the rfk pouch so car would not pick up on it, Low and behold would not lock car, checked via camera phone and infra red working, put key in rfk pouch had keyless card in pocket and closed and opened perfect.
I lived with a dying battery myself for a while, had similar issues from time to time plus others like power assisted doors struggling a bit to open etc. As soon as I fitted a new battery the car felt very different. If you are getting 11.8V at rest then you should change your battery.
 

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