Battery Mysteriously Died: Turning on Headlights Kills Electrical System After Jump Start

I was just going to ask that. Start at the battery.

I hate electrical gremlins.

 

The engine/computer draws a small amount of current compared to headlights, so it's possible to drive on just battery power for a while with no accessories on. The alternator may only be putting out a small amount of current, enough to keep the battery charged while driving without lights.

Try measuring voltage at the battery with voltmeter with engine running, then with headlights on.

 

And the only reason I mentioned getting my oil changed was because when my truck was up on the hoist, the tech unbolted my skid plate and let it crash to the ground. I heard the crash from the waiting room and knew instantly what it was. Because of that, I made them a suspect in this even though they probably had nothing to do with it...probably.

I guess I'm going to start looking at all the connections now.

 

I'll try that.

 

I would get a multimeter and test the voltage while the truck is running. Then turn the truck off and test the voltage of the battery while it's still connected. Then test the voltage while the battery is disconnected. What this will do is tell you whether you have a parasitic draw somewhere in the system. For example if the battery doesn't drain while it's disconnected from the car, but it drains while it's connected to the terminals, that will indicate a parasitic draw. If it drains while it's on and off the car. Bad battery.

 

Went out to test the battery. The truck started right up. I shut it off and hopped out to go get the multimeter.

But before doing that, I noticed this USB cup holder thing I have that plugs into the 12v outlet.



I unplugged it yesterday when I was trying to start the truck. I plugged it in and tried to start the truck again. No go. Unplugged it and still no go. Just makes a click sound.

Too many variables for my little brain.

 

Start by eliminating possible problems. I'd still have battery checked and check alternator voltage. Or drive to oreilys and have them check alternator output on the vehicle

 

Truck started again. Checked the battery: running was ~14.1, not running was 12.5.

And it wasn't a click when I tried to start earlier. It's more like a buzzing sound, like a small electric motor is running. It's seems to resolve itself somehow after a short time.

 

I'm getting a starter vibe. But, I think the starter can't spin until the gear extends out. Maybe the motor you are hearing is the fuel pump?

 

And what is the voltage with headlights on, engine running and not running?

 

Check for a loose ground while you are at it.

 

Running, it was the same.

Isn't the fuel pump is in the gas tank?

 

Just checked again with the lights on. Running was about 13.8, not running was 11.98.

 

yes. If theres a electrical sounding whine when you turn the key on thats prob the fuel pump you hear.

 

Id get the battery load tested and alternator checked just to be safe.

 

do you have any corrosion in your electrical

 

That's my next move as soon as the guy patching a big hole in my dining room ceiling finishes.

 

Not that I'm aware of, but I haven't inspected the connections underneath.

 

Connections can look clean. The only way to be sure is to take them off the battery post. Just clean them to be sure. Eliminate the unknowns.

 

My mustang looked clean ended up being the ground wire corroded on the frame connection lol just an idea all your instances mimicked mine