The lifespan of a key fob battery is something most car owners rarely ponder—until it becomes an issue. For owners of vehicles like the Lincoln Nautilus, understanding the expected battery duration and potential early failures is crucial. This account details the surprising experience of a new Lincoln MKX (the Nautilus’s predecessor) owner with unexpectedly short key fob battery life, raising questions about battery selection and longevity.
This timeline begins with the order and delivery of a new MKX in late 2016. The vehicle was ordered on October 5th, 2016, with the VIN assigned around October 14th. After spending time in transit, arriving in Memphis around November 20th, and undergoing pre-delivery at the dealership, the MKX was finally delivered on December 12th, 2016. While the exact moment the key fob was first energized remains a factory detail, what followed delivery was quite telling.
Barely two and a half months after delivery, by February 25th, 2017, one of the key fobs was completely dead with almost no usage. The second fob, used intermittently and handled with care to prevent accidental button presses, was tested on March 1st, 2017, revealing a battery voltage of 3.014V. While 3.014V might seem reasonable, it’s important to consider battery specifications.
The key fob utilizes CR2025 batteries, with a nominal voltage of 3V and an ampacity of 165mAh, sized at 20mmX2.5mm. A fresh CR2025 battery typically measures around 3.32V at room temperature. The end-of-life voltage is considered to be 2.0V, and around 2.9V at normal ambient temperature, battery failure is imminent. The fact that the tested fob was already at 3.014V after such a short period raises concerns about its remaining life, potentially only around a third of its total capacity, depending on the fob’s power demands.
Interestingly, the Lincoln MKX key fob uses two CR2025 batteries in parallel. This decision to use CR2025s instead of the slightly thicker and higher capacity CR2032 (225mAh, 20mmX3.2mm) is speculated to be a decision not driven by engineering necessities. Time will tell how long the second fob battery lasts. For now, spare batteries are proactively stored in the center console, a testament to the owner’s anticipation of further battery issues.
In contrast, a 2013 Lincoln MKS fob battery lasted for years, only requiring contact cleaning and lubrication before trade-in. Even a 2001 Dodge 2500 diesel key fob battery (CR2032) lasted an impressive 16 years before needing replacement. This early experience with the Lincoln MKX fobs certainly sets a low bar, and there’s hope that future battery performance will significantly exceed this initial, concerning trend.
