New battery and truck dead

[Raptors4ever]

Not sure what to do next. Bought a new battery and truck was fine for three days. Day four truck is dead after sitting overnight. Jump start and everything is fine. Go to work and it sits for 6 hours, starts right up with no problem. No lights are on, no accessories are on but is dead after sitting overnight. Maybe a bad alternator?

 

[Irregular F150]

Does sound like an alt issue… more experienced people can probably give you more insight.

 

[badm0t0rfinger]

Any sort of no start issue I always ask if you've done the fuse 27 mod. May not be it, but I always ask so we know a baseline.

 

[Nex]

What is the voltage while driving? What battery did you get and where did you get it from? Could have gotten a bad one. Also do a draw test on the system.

 

[Gryphon313]

Did you reset the BMS? It’s not as simple as just swapping in a new battery.

 

[MurderedOutSVT]

Did you reset the BMS? It’s not as simple as just swapping in a new battery.

This


Also, the parts store will do a load test (giggity) to see if it has a dead cell or anythjng

 

[Raptors4ever]

Did you reset the BMS? It’s not as simple as just swapping in a new battery.

Did not know this as I have not done this on any prior battery changes. Just did it and will see if great helps. Also will head to autozone to test alternator.

 

[Gryphon313]

Yeah. I am am sure many F150 owners have been in the dark about that. Basically, the pcm needs 8 hours of uninterrupted “off” time after you replace the battery to determine the new state of charge. Otherwise, it will treat the new battery as if it’s old and charge it accordingly. This can lead to early failure of the new battery and result in exactly what you experienced. You can force the reset on the BMS via several methods.

Also, when you jump start your truck, it is very important to ground to the chassis/body points and not the negative terminal on the battery.

 

[ziggy2022]

Did you reset the BMS? It’s not as simple as just swapping in a new battery.

BMS?

 

[Bozz]

BMS?

Battery Management System