How to avoid a dead Nissan Leaf after taking a long trip
While you cannot "brick" a Nissan Leaf, that electric car can be rendered dead if the 12 volt accessory battery runs down. A member of the MyNissanLeaf forum found this out the hard way. He'd left his Leaf plugged in to a charging station and left on a long trip, only to return to find his car "totally dead". After a "jump start" the battery pack was full, which leaves us puzzling over why a Leaf can appear dead with a full battery pack. Fortunately there is a simple answer, some advice on what to do if this happens to you, and how to avoid the problem in the first place.
The condition of the Nissan Leaf in question was described as "totally dead, locks won't made any sound when pushing the button, when I turned the lights on (inside) I did not see even a glimmer on the filament." How this came about is as simple as leaving the car plugged in to a charging station, and leaving on a 2 week trip to Hawaii. It's got to be a fairly attractive idea to leave the car plugged in to a charger, because that will keep the cars battery pack topped up. But this turns out to be a bad idea. As several people noted on the MyNissanLeaf forum, when the car is plugged in to a charging station it does not maintain the voltage of the 12 volt accessory battery, and that battery eventually runs down.
The 12 volt accessory battery on any electric car assists in running the 12 volt system. The 12 volt system controls the lights, information, and other systems, including the control circuits that allow the car to turn on. In other words, it's nearly the role as the 12 volt lead acid battery on a gasoline car. On an electric car the 12 volt accessory battery is not recharged by an "alternator" but by a DC-DC converter powered from the battery pack. DC-DC converters take battery pack voltage and produce the 12-13.2 volts required to run that part of the car. If the DC-DC converter is disconnected from the 12 volt battery, it will eventually run down.
The fix, if this happens to you, is to do a jump start. It's just like any jump start you've done with a gasoline powered car. Pull out your jumper cables, connect the black cable to the frame of each car, and connect the red cable to the positive terminal of the 12 volt battery in each car. This will bring 12 volts to the car, letting the 12 volt system turn back on. You may need to leave the cars connected long enough to recharge the 12 volt battery, but it will probably be enough to get the car turned on and from there the DC-DC converter should take care of recharging the 12 volt battery. A 12 volt automotive battery charger can also be used to jump start, because what's required is to recharge the 12 volt battery.
What's better is to avoid the problem in the first place. That is as simple as not plugging the Nissan Leaf in to a charging station if you're away for awhile. If it is a long trip you should disconnect the 12 volt battery, or connect a "battery tender" style charger to the 12 volt battery. As we noted a couple months ago, the Nissan Leaf can sit idle, and not plugged in, for a long time with no risk of damaging the battery pack.
However this is not a universal recommendation. When we covered the risk of "bricking' a Tesla Roadster we learned that Tesla's recommendation is, while on a long trip, to leave the Tesla Roadster plugged in, to keep the battery pack topped up and not risk being damaged. The universal recommendation, then, is to study the specific needs of your car, starting with the contents of the owners manual.
You can read all the details on the mynissanleaf forum.