Ninjarider1978 wrote:Ok, makes sense, seems like the best fix would be for Nissan to properly charge the aux battery when the vehicle is ON. Not sure if that's what the fix was supposed to do or what the deal was but I guess in the meantime I will be topping up the battery occasionally with a separate charger.
The problem there is the car has no prior knowledge of how long you'll leave the car on in seconds, minutes, or hours. The faster it charges the more damage it can do to the 12v and can cause off gassing (fire/explosion concerns). The slower it charges it may not complete before you turn the car off again.
Another factor is you can only reliably check the voltage on a 12v battery with a steady known load and no charging occurring. But the systems in the car will vary the load as each subsystem is powered up or down. They could make a special diagnostic menu for 12v battery check and charging profile but there is no great way of automatically getting the charge profile right given the three gotchas
1. safe disconnect when off
2. unknown time on / unknown time off
3. variable loads while on and off
Toyota did it way worse with the 2004-2009 Prius, Slight improvement for the 2010-2015 Prius. But the failure mode is the car won't turn on, the brakes are always safe to use because their capacitor dedicated to the brake system works to prevent the issue the Leaf sees.
Tesla has a different issue but still is killing 12v batteries way too often because they have a higher vampire load when the car is off. They have the dash tell you to go to the service center and get a free 12v when it gets too weak. AKA they throw money at the issue (replace the battery proactively at the first sign of weakness). See http://www.teslamotorsclub.com/showthre ... rvice-Tech
if you want details.
Nissan has more of an issue with the Leaf that doesn't have the solar panel, probably on par with what you'd see on a current gen Prius. Less of an issue with the Leaf + solar panel as it gives a little bit more charging when the car is in the sun. Not much but better than nothing.
What Nissan needs to do is either
A. make the system immune to the brake issue like Toyota did (redesign, retro fit, hardware change)
B. make the system immune to the issue by pulling a Tesla and have it tell you to replace the battery (software change)*
* The software could tell you to manually charge the battery instead of replacing it but if Leafs start popping up battery warnings even 12v related it'd have a negative connotation.
End result is Hybrid or EV there is no easy answer. If you as the end user maintain the 12v your issues will be less than if you trust the car to try and do it on its own.