Tesla also has no smart 12V monitoring. Same failures happen like with Leaf.
BMW uses extremely smart, self-sustaining module right on the negative terminal of the battery
(powered directly from battery) starting from 2005. And some other premium brands as well.
It reports to driver : a) battery has been discharged slightly b) battery has been discharged deeply
c) yellow warning, battery degraded, replace recommended soon d) red warning, battery is no good
With A/B it recommends to to charge battery (or drive ICE vehicle for longer).
12V battery SOC is monitored like Leaf monitors HV battery. 24/7. Until voltage drops to near zero.
It recalculates capacity according to Ah consumed, voltage, temperature, etc.
BMW keeps battery charged at 70-80% state of charge. This way 12V AGM batteries usually last 4-8 years.
But they all die eventually.
So Nissan and Tesla could all implement this basic tech. But they don't. And I don't know why.
For ICE vehicle it adds like 300-400€ of cost. But for EV, 12V converter is already capable doing all that is required.
Examples of messages:
Some vehicle functions are not enabled until battery is adequately charged during driving.
This one explains that there was abnormal draw during resting period.
For example, during very long parking periods (months) when BMW owner comes back to vehicle he/she might
be surprised that doors do not open. Well this BMS was counting all the amp-hours that have been used up during sleep
and right before it is too late it switches off those last consumers, like clock settings, telematics, alarm and central locking.
But opening the door manually with physical key will wake up the vehicle and will allow that last cold start.
With the price of slight inconvenience (clock, seat memory, radio memory etc) and not able to use many power hungry
electronics for limited period (like half an hour), owner doesn't have to call a friend for a jump.