I recommend my own easy to follow instructions for vehicle long-term-storage (3+ months).
There are many steps missing that apply to vehicles with combustion engine.
Most of these steps apply to all EV-s but are specifically written for Leafs.
0) Wash the car thoroughly. Be sure to remove salts and tar. Wash wheel wells. Vacuum the interior.
Throw out all junk, air-fresheners. Purge all windshield washer fluid in case it might freeze.
Inflate tires to 20% above recommended. So instead 2.5bar (36psi), 3.0bar (43psi) is definitely enough.
If you have newish wiper blades you can remove them and store them in the vehicle. Cover metal
arm with piece of tape or cloth and set to rest on the glass surface. Do not raise bare metal arm up for
more than a second as if you accidentally flip it down without supervision you will crack your windshield.
It's safe to leave the metal arm touch the glass when you do the second wiper.
1) Discharge main battery to anywhere between 30-50%.
2) If you have used AC lately, turn it off manually and blow hard hot air through HVAC system for 15 minutes.
If it is freezing outside, turn on recirculation mode for 10 minutes and turn off again for last 5 minutes.
3) Close all windows fully*, fold the mirrors. Engage Park, disengage parking brake (e-brake) and switch vehicle off.
Fold the rear seat down (at least one half).
4) Remove floor mats, clean them and store in the trunk. Keep them flat. This is especially recommended for damp climate.
5) (In case of damp climate) If you have, place dry (unused or regenerated in oven) desiccant onto the floor of front passengers.
Anything less than a kilo is too little (two pounds).
Or go get a high quality cat litter as an alternative, many will absorb moisture from the air (find ones that are have air-tight package).
Fill two socks, tie them up and place on floor. One extra in the trunk will help. Also there are salt dehumidifiers available.
6) Open the hood.
7) Verify that vehicle has been off for 5 minutes and then disconnect NEGATIVE battery terminal from 12V battery.
Tie it up with zip tie or wrap with plastic so it will not straighten itself back and touch the battery terminal later on.
Keep the wrench in the car for later use.
Alternatively, you can connect 12V trickle charger. Be sure that voltage does not go above 14V as this will degrade battery.
8) Close all 3 doors manually from inside. Close driver's door with mechanical key. Verify all 4 doors are locked. Verify charging
port is closed. Verify trunk is closed. Close the hood. Remove the battery from both keys. Leave the keys stored. Don't drag them with you.
Vehicle is now offline and locked.
It is recommended to keep vehicle in averaged ambient temperature between -15*C (+5*F) and +15*C (60*F) if possible.
Storing at up to +25*C (75*F) is acceptable.
9) Please return to the vehicle once every 6 months to recharge 12V battery
Either with external 12V battery charger or by switching vehicle on or charging the vehicle
(two hours in sub-freezing temperatures, one hour in mild temperatures).
Keep in mind that even if 12V battery is recharged with external charger you still have to
reconnect the negative terminal to wake the vehicle up to verify traction battery state of charge.
Expect to lose up to 5% of battery charge if you recharge 12V battery with main battery (no driving, no HVAC usage).
There is no need to "warmup test-drive" the vehicle, especially if it gets dirty.
Verify that state of charge of main battery doesn't dip below low battery warning nor too much for you to reach closest charging location.
Also visually verify that tires are still adequately filled. If possible, move the vehicle for quarter turn of the tires (one feet, half a meter).
Verify that emergency brake is released and switch off the vehicle once again.
*If you keep your vehicle in closed garage, especially heated/dry one, you can leave all 4 windows slightly open (one finger gap)
and skip desiccants. Natural air circulation will dry out vehicle if kept in dry garage.
Do not keep EV plugged in for months. It will raise state of charge and will not guarantee topped up 12V battery.
Power might go out or breaker might trip or plug might be unplugged or EVSE might be unplugged or lightning can damage unattended EV.