Electrical oddities

[Nibroc99]

Update: Battery is fine, took a charge no problem. I'm doing some more testing because after going for a long drive yesterday and testing the battery when I got home - it was back to 10.5V. Something is obviously wrong. Today I will charge the battery back up, leave the battery alone (i.e., not connect it to the car, and see how long the voltage remains at ~13VDC). Then I will connect to the vehicle and see what happens over time.

That almost sounds like a bad alternator to me - I would do your test on the battery first, and I'd also check the alternator for sure. Almost sounds like it's not charging the battery.

 

[Nibroc99]

Update: Battery is fine, took a charge no problem. I'm doing some more testing because after going for a long drive yesterday and testing the battery when I got home - it was back to 10.5V. Something is obviously wrong. Today I will charge the battery back up, leave the battery alone (i.e., not connect it to the car, and see how long the voltage remains at ~13VDC). Then I will connect to the vehicle and see what happens over time.

Just so you know, my alternator is healthy and goes between 14.6 volts and 13.8 volts (usually sticks around like 14.2-14.6 range while driving). Just so you have a number to look for.

 

[runningonfords]

Just so you know, my alternator is healthy and goes between 14.6 volts and 13.8 volts (usually sticks around like 14.2-14.6 range while driving). Just so you have a number to look for.

How do you know the alternator's output while driving?

 

[Nibroc99]

How do you know the alternator's output while driving?

I have a 12V outlet phone charger with a live voltage readout. It reads 12.6-12.8 volts when the engine's off, and it reads what I said while driving. Pretty handy tool, and I did confirm it's accurate with a multimeter and a friend reading both readings. My friend held the pos and neg poles of the multimeter to a positive and negative wire I have for aux lighting, and it matched the voltage reading of the phone charger spot-on. Pretty cool. (I have a Ford police interceptor utility to clarify, always have the dash apart working on wiring things haha)

 

[runningonfords]

Oops, nibroc I confused you with the the original poster. Mueller should check his belt tensioner and belt health too.

 

[Nibroc99]

Oops, nibroc I confused you with the the original poster. Mueller should check his belt tensioner and belt health too.

No worries! And also good point - if the belt is slipping it can't turn the alternator very well!

 

[MuellerAndrewRay]

Oops, nibroc I confused you with the the original poster. Mueller should check his belt tensioner and belt health too.

I had the serpentine belt replaced just a few months back. Should be in GREAT shape since the dealership charged me 2 hours labor for a job that took them only 45 minutes (I watched). They also washed the car which took them the rest of the time (time not spent waiting for the part).

 

[1Neptune]

Seeing that your alt output is pretty good then it seems that there is a faulty connection/wire problem. Between the alt and batt. One other thing is to check your starter for shorts. Even small amounts of current being drained while driving. Good luck in tracing it down.

 

[Nibroc99]

Seeing that your alt output is pretty good then it seems that there is a faulty connection/wire problem. Between the alt and batt. One other thing is to check your starter for shorts. Even small amounts of current being drained while driving. Good luck in tracing it down.

OP never posted about their alternator output, but I did for them to reference. They should still test their alternator output too.