Battery going dead

[Bucephalus]

Anyone experiencing issues with the engine battery suddenly going 100% dead overnight? Jump starts easy and performs fine for a time...and then repeats. No check light, no codes, no explanation, no pattern? Had techs plugin and found nothing? Anyone?

 

[Cdubya]

If you are sure your battery is good, is probably some parasitic draw. One potential issue I found with my 2020 ST was that the on some occasions, the headlights would not turn off--the headlight switch would not turn it off either. I always managed to catch it before the battery completely died but replacing the headlight switch/module solved the problem. 2020 also had issues with deep sleeps and what I would assume are parasitic drains--TSB out there saying to update modules to newer firmware. It might be hard to solve, especially if this happens intermittently. I personally recommend having a voltage display in the car--my radar detector does that but some use a cig lighter plug that displays it. At least you will know if your alternator is performing correctly. Others will tell you to reset the BMS (google procedure).

 

[EDWYER]

How many miles do you have on it?

 

[Nascarbilly]

Anyone experiencing issues with the engine battery suddenly going 100% dead overnight? Jump starts easy and performs fine for a time...and then repeats. No check light, no codes, no explanation, no pattern? Had techs plugin and found nothing? Anyone?

@Bucephalus :
Do you have an aftermarket alarm system? My 2016 GT Premium Convertible would not start if it sat for more than a week (if you drove every other day, NO problems/no indications). After being towed back to the selling dealer (3) three times, battery/alternator replacement and countless calls and emails with FORD they accidently figured out the problem. The car alarm was installed wrong and was somehow getting a electrical ground that was killing the battery.