2009 Mercury Mountaineer Premier 2wd Battery would not hold a charge even off the vehicle max would be 10.2 after drain down. Replaced battery had vehicle checked with alternator comp, said voltage re
I see no check eng light & dont know if putting this on a scanner will tell me what the issue is or not.. if so where to go to test it in the scanner system?
Cars & Trucks - Mercury - Mountaineer - 2009 Mercury Mountaineer
Answers & Comments
IF a battery drains down when out of the vehicle it indicates an internal fault in the battery (bad cell)
Most vehicles do not have anything in the CPU to refer to the alternator or charging system unless it is really late and upmarket model where the ECM provides regulation for the alternator output.
you can check the out put yourself by attaching a mulitmeter across the battery terminals and set on dc volts . Start the engine and see the volts at around 2000rpms. turn on the head lights and re-chech the voltage at 2000rpms
the voltage in both cases should read 14.5-14.7 volts
If it is lower or over that there is a problem in the regulation of the alternator output and should be checked by an accredited auto electrician