According to a recent tweet from Tesla owner and software data miner @greentheonly, Tesla has added new fault codes in its latest firmware versions to warn users when a “pyro fuse has reached life expectancy.”
Tesla is adding a "pyro fuse has reached life expectancy" fault codes in latest firmwares because pyro fuses in model s/x battery packs in 2015 to 2018 range used non-replaceable li-ion batteries only rated for ~10 years.
The tracking is done by fuse manufacturing date. pic.twitter.com/0OSOrHCtHb— green (@greentheonly) January 28, 2022
A pyro fuse (or switch) serves a vital function in crashes, exploding and destroying the circuit between the two halves of a Tesla’s battery pack. This immediately cuts the voltage in half, avoiding a short circuit or battery fire.
The warnings have been added because the pyro fuses used in battery packs for the 2015-2018 model year Model S and Model X vehicles were powered by non-replaceable lithium-ion batteries that are only rated to last approximately 10 years.
The fault codes will track the status of pyro fuses by their manufacturing date, warning users and putting the car in Limp Mode when a fuse crosses its end-of-life threshold.
Pyro fuses are an essential safety component and will need to be replaced once they’ve reached their specified end-of-life.
Whether Tesla will offer free replacements for pyro fuses as they fulfill their life expectancy remains to be seen, but 10 years past manufacturing is well beyond the warranty period the company offers for its electric vehicles (EVs).
If you want to learn more about this, there's a great video by @ingineerixhttps://t.co/8XDHVCwvQs
If you scroll to the 11:50 mark – the expected lifetime and replacement parts they used is spelled in newer packs.
— green (@greentheonly) January 28, 2022
To learn more about pyro fuses and Tesla’s implementation of them, check out @ingineerix‘s YouTube video on the subject below and how the automaker came up with a new solution to no longer need batteries for pyro fuses:
Tesla on Tuesday started rolling out software version 2022.4 to users, and Full Self-Driving (FSD) beta 10.9 was released alongside software version 2021.44.30.10 earlier this month.
