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Old 01-05-2013, 12:22 PM
JNMNL52 JNMNL52 is offline
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Location: Woodbridge, Virginia
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Mein Auto: 2006 X-5 / 2014 X-5
Delayed alternator charging in cold weather

Long story short been experiencing red battery symbol lights for the past three weeks in the mornings. Lots of troubleshooting since got me to this point. Each time the battery light has come on it has been soon after the first engine start of the day when the engine was cold and the outside temperature around 30 degrees. I performed voltage tests on several occasions, during engine start and observed that the alternator did not charge. When the voltage dropped to 11.5 the red battery light came on. Then after 5- 15 minutes I hear a surge in the engine and the alternator starts charging on its own and the light goes out. Once warmed up after a few minutes the system charges normally at 14V all day long. It will not happen again the rest of the day/night. This is just a problem in the mornings for a few minutes. I am trying to zero in specifically on the problem and not convinced it is the alternator at this point. When charging I turned on all all electrical systems -- steering wheel & seat heaters, wipers, high beams, etc. Voltage stayed at 13.7. No current or pending OBD II fault codes are indicated when the alternator is not charging. I inspected the drive belt while the engine was running with no alternator charge and there was no slippage. The tensioner spring is tight and normal " play in the belt when static. I am thinking there is a contact in the charging system that is not making contact when cold, but after running a few minutes, warms up and makes contact allowing the alternator to charge. My suspects are: voltage regulator which I thought was solid state with no electrical contacts, the wiring harness connector plug on the voltage regulator or the battery cable connection on the voltage regulator. I was unable to check the connections on the regulator because of the alternator's location requiring disassembly of various components. This is where I am. So a few questions to the group:

Has anyone experienced this problem before? Any ideas on what is going on? Are there electrical contacts within the regulator?

Last edited by JNMNL52; 01-05-2013 at 01:42 PM.
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