JRoque said:
... Correct, the 12V battery does not instantly charge after a jump start. My point was that big jumper cables and another vehicle, as it is typically done with ICE, are not needed. As long as the 12V rail is somewhere near that, the vehicle will initialize and the DC-DC takes over. Yes, you have to run the car and/or charge it to get the 12V fully charged.
...
But the LEAF 12V charging protocol will leave it not fully charged to the fully charged state that a good quality 12V trickle charger will.
I watched the current flow to very discharged 12V on the LEAF the other day.
Was down around 9.6V, just barely enough to start the LEAF.
And the LEAF DC to DC does initially put 100 amps into the 12V for a long time.
But once it drops back to 13V float, it then periodically sees that float current is too high, and bumps back up to 14.6 V periodically with current into the 12V at 15 amps to 20 amps range.
But after spending 5 hours charging the high voltage pack to 100%, when you put an external 12V trickle charger on it will take at least six hours for the 12V to show fully charged.
The LEAF protocol does not fully charge the 12V.
If you don't have a current drain problem like you and BrovkWI do, and you drive the LEAF frequently a 12V might last five years.
But if you do have current drain problem and don't drive frequently and do not use an external 12V trickle charger, then you will rapidly destroy the 12V which is what you have been doing.
I agree the LEAF DC to DC should be able to fully charge the 12V.
But in your situation it does not.