Ford’s Mustang Mach-E EV is pretty damned impressive for a first effort at a built-to-purpose electric vehicle. Of course, no new model is without its faults, and the owners of some early Mach-E examples have found a significant fault with the 12-volt battery system.
According to a report published on Thursday by The Verge, some owners of these very early Mach-Es are going out to their vehicles after leaving them on the charger overnight and finding the vehicle in something called Deep Sleep Mode. Essentially, their fancy new EV is bricked.
How does this happen, though? Well, it has to do with the way that the vehicle’s 12-volt battery keeps itself charged. In an internal combustion vehicle, the battery is charged by the alternator when the engine is running. In the Mach-E (and most EVs), the 12-volt battery siphons off some of the energy from the big, high-voltage propulsion battery. But in these Mach-Es, the vehicle computer wouldn’t let the 12-volt battery do that if the vehicle was on a charger.
Without being able to charge itself, the 12-volt battery would drain overnight in some instances, and the vehicle would become unusable. The battery could still be jumped, like on an internal combustion vehicle, but because the battery lives in the Mach-E’s frunk, which is latched electronically — with the latch’s power coming from the 12-volt battery — you’re kind of out of luck.
“We are aware that a small number of Mustang Mach-E owners have had their 12V battery reach a low voltage condition,” a Ford representative said in a statement. “We proactively worked with early owners experiencing this issue to identify the root cause and a fix. In the rare instances where this still occurs, customers can now contact their local EV-certified Ford dealer to have the matter resolved.”
Ford has issued a technical service bulletin to assist its technicians with sorting out this issue, but it hasn’t turned into a full-blown recall as of yet.