Electrical woes

[jfoj]

I also charge pretty consistently around 13.8 watching my UltraGauge.

[jfoj]

Might humor me and try this, not sure it will resolve anything.

Disconnect the battery and short the battery cables together for at least 30 seconds.

Reconnect battery terminals, start vehicle and see what if anything is different.

[wsmeyer]

You must be as old as I am. I do that whenever I change a battery. No idea if it does anything on newer cars but couldn't hurt.

[jfoj]

Actually does more on the newer cars than the older cars.

Often times one or more of the cars modules can go stupid and often the capacitors all need to be discharged and put back in a "known" logic state.

Not sure if this is a problem with these cars, but sometimes certain programming/configuration can be lost or corrupt.

Before I would pull the alternator, I would be trying to re-register the battery first.

What is a bit strange/unusual is you do not mention that there is any sort of indicator that there is a charging/electrical problem.

[wsmeyer]

So this morning battery read 12.54V started car and it dropped to 12.4V. I let the car idle with headlights on and it steadily dropped for a good 1/2 hour then at 11.95V it jumped to 14.x. I immediately shut off the car and battery read 12.7 and car fired right back up. Acting normal again now.

[jfoj]

You need to monitor the Voltage to see what is going on.

There may be an intermittent problem still.

Use the OBDII App and Log the engine RPM, Speed and Voltage for a few days.

If it was me, I would confiscate the car from the wife for a few days to make sure things work properly, otherwise your X5 will be traded for a Silver Honda Odyssey!

[wsmeyer]

I have been logging it since yesterday. Nothing strange till this morning. When it had gotten down to 11.95V I was certain the car wouldn't start, then when I shut the engine off I was surprised to see the voltage jump to 12.7 and even more surprised when it fired right back up.

The whole time it was idling in the garage I had both the BlueDreiver and my Fluke meter attached and they both read the same.

[jfoj]

Either the alternator is not charging, this is why the Voltage is around 11.95 Volts and/or there is a bad connect with too much Voltage drop.

Where are you taking the measurement with you Fluke?

Do you know how to perform Voltage drop measurements?

Have you taking a jumper cable cable and connected them to the negative under hood jumper post and then connect to a good solid metal engine part? This adds a supplemental engine to body ground. If there is an obvious change in the Voltage when the jumper cable is connected, chances are the body to engine ground is bad.

Something still does not seem right, I see a Silver Honda Odyssey in your future.

[wsmeyer]

Originally Posted by jfoj

Either the alternator is not charging, this is why the Voltage is around 11.95 Volts and/or there is a bad connect with too much Voltage drop.

Where are you taking the measurement with you Fluke?

Across the jump points.

Originally Posted by jfoj

Do you know how to perform Voltage drop measurements?

Yes but cars are almost exclusively parallel circuits so I'm not sure where that apply.

Originally Posted by jfoj

Have you taking a jumper cable cable and connected them to the negative under hood jumper post and then connect to a good solid metal engine part? This adds a supplemental engine to body ground. If there is an obvious change in the Voltage when the jumper cable is connected, chances are the body to engine ground is bad.

Definitely will try this

Originally Posted by jfoj

Something still does not seem right, I see a Silver Honda Odyssey in your future.

Why would you be so mean to someone you don't know?

[jfoj]

Originally Posted by wsmeyer

Why would you be so mean to someone you don't know?

All the women go to the same school and do the same thing. If the BMW strands her again, its/your days are numbered!