I have always gone along with the frustration and irritation felt by EV owners over 12V issues. I have driven EVs for 9 years now, and back then it was a serious problem. I had two incidents with an early Leaf 24. Over the years, various tweaks and software upgrades have reduced the problems. But the fundamental problem has always been that, gradually, some driving patterns allowed the 12V battery to become at a lower and lower voltage until eventually it failed as the voltage became so low that it wouldn't even throw the relay to engage the traction battery on start-up. Critically, this boiling frogs situation went on unnoticed by the driver.
What I didn't know at the time was that such abuse of a standard lead/acid battery by frequent and prolonged low voltage periods would inevitably lead to the death of the battery. And as it went unnoticed for months at a time that was often the result.
At that time everybody drove ICE vehicles and this was never a 'thing' because we were always made aware of a failing 12V battery because it began to be sluggish when turning a cold ICE engine over. We then immediately took action to charge it and/or change it for a new battery if it was a few years old. However, in an EV no such early warning was given. Just a final incident and a dead battery.
At that time, I recognised that early warning would be key to avoid such incidents and I began to pay closer attention to the condition of the battery. I started to clip on a smart mains battery charger as part of the monthly regime of tyre kicking and screenwash bottle filling. That kept away any possibility of a gradual voltage drop, and since the early Leaf issues, I have had no 12v problems. I attribute this to my closer attention to this normally forgotten piece of equipment.
Later, I fitted a BM2 to make such monitoring easier. And on one occasion, this has indeed flagged up a low voltage and less than 50% SOC in the 12v battery. At that time the car was just over 3 years old and I took the opportunity to swap the OEM L/A battery for a modern AGM battery, as common advice was that they could tolerate such low voltages better.
The point of this narrative is to say that I fully understand the people who prefer to stand on their dignity and proclaim that such attention should not be necessary. And that they would instead insist on their 'rights' in warranty terms and then official bodies if that failed to deal with their car being bricked. They are correct, of course. Such is common in modern thinking.
But personally, I am of an age where we didn't always seek to blame others for any problem in our lives. I prefer to take some level of personal responsibility to avoid such problems by being proactive, as long as the means just involve a bit of vigilance.
So, I check the BM2 regularly. Takes a few seconds to fire up the Bluetooth app. And I attach a smart charger overnight once a month as they can check for any developing problems and can repair and then float charge to balance all cells if needed. Such minimal attention is part of my overall philosophy of preventative maintenance being preferable to being locked out at 2am one rainy morning in an airport car park.
Perhaps that's just me. And I should relax and be prepared to do battle with third parties instead. But my strategy has worked over the 12V saga for the last 9 years, and I will probably continue with such an old-fashioned approach.
