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

This is a mystery to me and I'm hoping the TW collective can shed some light.

Somehow my 2-1/2 year-old battery went dead while I was at work yesterday (10/3). Went to start it and got absolutely nothing. No dash lights, no beeps, no radio, nothing. Wouldn't even try to turn over. It was like the battery was disconnected. However, there was enough juice to turn on my auxiliary lights momentarily, but they were pretty dim.

I jump started the truck and drove home. I noticed my radio reset. On the way, I turned my headlights on and the truck immediately shut down. I turned the lights off and everything was fine.

I don't know enough about auto mechanics to rule out anything, so I'll list everything I know that could be a factor.

• Had my oil changed and tires rotated on Saturday
• I installed new brake pads on Sunday; brake fluid leaked from the reservoir when I pushed the caliper pistons back, enough to drip on the floor
• I have the "Ultimate Headlight Upgrade" harness running 100/90 watt bulbs and have had zero issues with it (headlights worked just a few nights prior)
• No issues starting up until yesterday afternoon

When I got home, I turned my lights on again while the truck was running and it died. I removed the headlight harness and inspected it for exposed wires that might be causing a short. I didn't check or test its two relays. It was a little dark, so I'm going to take another look at the harness.

After removing the harness, I connected the OEM sockets and hooked up a battery charger hoping the battery would recharge overnight. The truck started this morning while the charger was connected. I disconnected the charger while the truck was running thinking everything was ok. I shut the truck off and tried to start it again and got nothing. Same as before.

Thanks in advance for any input.

 

bad alternator, not charging battery...
headlights draw a ton of current, btw.

on an offroading trip, a buddys alternator went out. popped in a new battery and had to drive him home in the middle of the night with his headlights off for him to make it back, battery power only

 

Take the battery out and have it checked by autozone. Sounds like battery went bad. Battery terminals clean?

 

Did you try a different battery? You can damage a battery by drawing it down too deep and it won't take a charge after that. Potentially the charger will say it's charged, but the capacity of the battery will be significantly reduced. It's possible as xperivent said, maybe the alternator went bad which would've then made the battery die too. At least those are the first things I'd check.

 

If you didn't notice a battery light on dash anytime before this, then it's probably a bad battery.
If aux lights were LED, low power draw of le explains how they were able to be a little dim.

 

Terminals are clean. Going to take it to O'Reilly. That's where I bought it. Just seems strange that it completely drained in eight hours.

 

Hadn't considered the alternator. For what it's worth, I have a the Ultragauge Blue on my phone and it indicated the battery was charging.

 

Haven't tried a different battery. I had no indication the battery was draining. Starts were strong. If the alternator failed, wouldn't my battery just get noticeably weaker after each start? My battery seems to have fully drained over the course of a work day.

 

Around 14.2 if I remember correctly. It's usually around there.

 

If my battery was completely dead and the alternator wasn't charging, wouldn't that keep the truck from running? I apologize if that's an ignorant question.

 

Nvm.


I don't disagre with anyone else, have O'Reilly check the battery first.

 

if your alternator is not working it uses the battery to run. If the battery is toast it basically negates the alternator where it will barely run but turning on anything else typically uses all the power and doesnt let it run. If your alternator is still good, the battery can be toast.

 

So, one possibility is the alternator is bad and the battery held enough juice to get me home and turning the headlights on interrupted that. That makes sense.

I've experienced driving with a shot alternator, driving on battery power only, but I've never experienced a battery draining so quickly between starts without something being left on. There are usually signs, like the typical slow cranking delivered by a weak battery. Mine fired right up in the morning and didn't even try to turn over in the afternoon.

 

And that's what I find puzzling about the bad alternator scenario. If my truck had no problem starting in the morning, it would suggest that the battery was, at least, in fair condition and holding a good charge. And if the alternator was charging on the way to work (if we trust the Ultragauge Blue) and somehow failed before I parked, I would think my battery would have enough power to start my truck 8 hours later unless something was draining it during that time.

Going to go pull my battery now.

 

Ok. I went to pull my battery and thought I'd try to start it just for fun.



It fired right up.

 

It's a ghost

 

And turning my OEM headlights didn't cause a problem.

 

Loose connection somewhere?