Long term EV storage procedure

[arnis]

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.

[LeftieBiker]

I disagree with three of the above.

First, washing a car that you are about to store makes it likely that rust will form in places that normally get dried by moving air after the car is washed. This also includes the brakes, which should be used enough to heat them up after any washing. If the car isn't dirty, don't wash it! If it is dirty, wash it well before storage begins, and drive it afterwards.

Second, leaving the 12 volt battery connected for that long may or may not work - it's a roll of the dice. Disconnecting the battery terminals and then fully charging the battery will guarantee that it stays charged - with no top ups required.

Third, in colder weather when the battery warmer may come on, 60-80% is a safer storage charge. In this case charge the 12 volt battery but leave it connected, with ALL 12 volt accessories off or disconnected. If it appears the battery warmer may run often, consider heating the storage space just to 20F or so to prevent this.

[arnis]

I disagree with three of the above.

First, washing a car that you are about to store makes it likely that rust will form in places normally get dried by moving air after the car is washed. This also includes the brakes, which should be used enough to heat them up after any washing. If the car isn't dirty, don't wash it! If it is dirty, wash it well before storage begins, and drive it afterwards.

Second, leaving the 12 volt battery connected for that long may or may not work - it's a roll of the dice. Disconnecting the battery terminals and then fully charging the battery will guarantee that it stays charged - with no top ups required.

Third, in colder weather when the battery warmer may come on, 60-80% is a safer storage charge. In this case charge the 12 volt battery but leave it connected, with ALL 12 volt accessories off or disconnected. If it appears the battery warmer may run often, consider heating the storage space just to 20F or so to prevent this.

1) you think that if you "store" a vehicle, time stops and vehicle will stop drying up? Well that is ridiculous. Driving has little to do with drying the vehicle. Car has plenty of time to get dry as it is still in ambient air. Also it's the salt that corrodes surfaces, not clean surface. Brake discs are designed to get rusty. People can't stop judging rusty brake discs, which is... pointless. Stating "don't wash a clean car" gives no new information anybody should learn.

2) There is no such thing as "that long". Procedure is for long term storage. EV or not, connected or disconnected, all batteries will deplete in normal ambient temperatures. Charging lead acid battery to 100% doesn't guarantee anything else than around one more extra week-month of storage before it reaches optimal recharge window. This thread is not for discussion of lead acid battery deeply. There are other topics full of it (and with my replies AFAIK).

3) Mostly incorrect. Battery warmer will come on not in "colder weather" but very cold weather.. with 24h average below -20*C (-4*F). That is rare for most and shouldn't be called "regular cold weather". Having any higher state of charge gives absolutely no advantages as heater will drain HV battery to optimal low state of charge (within a week) and stop operating after that. And IF very cold temperatures are going to happen then no state of charge will be enough to last conservation period. More importantly, 12V battery has nothing to do with HV battery heating as heating system is controlled by BMS which is powered by HV battery, not 12V system.
Considering heating storage place is not acceptable waste of resources with zero advantages. Same as saying Tesla should actually be plugged in for half a year for storage. Teslas have gigantic parasitic draw that will actually cost money to run from the grid. And it will still cycle 12V battery a lot, degrading it significantly (more than with daily vehicle usage).
Lithium ion batteries will freeze no sooner than -40*C (-40*F). If that temperature is unheard of then there is absolutely no reason to worry about. There is no need to keep battery warm enough so it could drive without turtle... for months and months.

Not a thread to discuss technical aspects of things that are self-evident (like store the vehicle in clean shape). Though there might be more things to do for better results.

[LeftieBiker]

Arnis, your arrogance is impressive, although maybe not for an Estonian. What I wrote about washing cars and them 'putting them away wet' is very true for all but the driest climates. Water pools in areas that are mostly enclosed. It dries much faster when the car is moving than when it is parked. Believe that or not - it isn't controversial.

What I wrote about putting away brakes wet unnecessarily is also true; while they aren't going to be unusable when storage ends, they will be rustier and noisier than most people would like. Leaf brakes in particular will get a fine layer of rust on the rotors after a normal rain - there is no reason to 'pre-rust' them.

Finally, a 12 volt battery that is fully charged and disconnected will stay charged for many months longer than a connected one, especially in a modern car. Again, what you choose to believe is your concern. Just try not to post what you happen to think as set-in-stone fact.

[Logger]

@arnis, I think you are incorrect when you say, "Please return to the vehicle once every 6 months to recharge 12V battery. "

Page EV-5 in the 2017 Leaf owner's manual says:

While the vehicle is not in use
When the EV system is off for an extended time,
the 12-volt battery may be automatically charged
for a short period of time on a regular basis.

So looks to me like one does not need to worry about maintaining the 12 volt battery, as the Leaf will do that for you, as needed from time to time.

There is also this tip under "MAINTENANCE PRECAUTIONS" on page 8-6, which describes a method to override this automatic charging:

The power switch is in the OFF posi-
tion. Place the power switch in the ON
position and then in the OFF position
to prevent the 12-volt battery auto-
matically being charged by the Li-ion
battery. For additional information, re-
fer to “Charging the 12-volt battery” in
the “EV overview” section of this
manual.

So if you intend to store the car long-term, make sure you drive it and then just turn it off. Don't turn the switch OFF-ON-OFF before you store the car. In other words ON-START-DRIVE-OFF is ok.

[LeftieBiker]

Depending on the year Leaf (2013 is worst, 2015+ are best) it may not charge the 12 volt battery as well in storage as the manual suggests.

[arnis]

@arnis, I think you are incorrect when you say, "Please return to the vehicle once every 6 months to recharge 12V battery. "

No I'm definitely correct. Please read Step 7 again.
The best way to recharge 12V battery is to reconnect negative terminal and start the vehicle for few hours. Then switch off and disconnect again. Vehicle will recharge 12V battery. If in doubt, additionally, plug from current sensor on the negative terminal can be disconnected temporarily for 12V battery recharge. This will guarantee maximum safe charging speed is used (recommended to save time), that includes 2013 Leafs.

[Lothsahn]

@arnis, I think you are incorrect when you say, "Please return to the vehicle once every 6 months to recharge 12V battery. "

No I'm definitely correct. Please read Step 7 again.
The best way to recharge 12V battery is to reconnect negative terminal and start the vehicle for few hours. Then switch off and disconnect again. Vehicle will recharge 12V battery. If in doubt, additionally, plug from current sensor on the negative terminal can be disconnected temporarily for 12V battery recharge. This will guarantee maximum safe charging speed is used (recommended to save time), that includes 2013 Leafs.

I understand what the manual says, but there's a lot of evidence in the forums from people with dead 12V batteries that the Leaf both does not properly do the maintenance charges on the early years as documented, and does not use enough voltage to properly top off the batteries. It also appears to potentially be a problem only affecting certain cars, as my 2011 is still running fine on the original OEM battery--something that is quite uncommon.

Another bug in the early Leafs is if you leave the EVSE plugged in, it tends to drain the 12V battery rather quickly. My 12V battery will be completely dead if left plugged into the EVSE for 3 days without turning the car on and not charging. This is quite silly--the car has power both at the lithium pack and from the EVSE, but it does not use it to top off the car's charge. I've heard it's related to the car frequently polling the EVSE to see if it's still plugged in.

My recommendations before storing the vehicle, which echo yours:
1) Charge or discharge to a 40-50% SOC
2) Unplug the EVSE
3) Disconnect the 12V battery
4) Store in a cool, preferably dry location. 35-40F would be the ideal storage temperature.
5) Check on the car at least every 6 months. Top off the 12V battery and charge the car back to a 40% SOC

[cpmiller15]

Thank you for this vey helpful information. I am a new LEAF owner and will be leaving for summer for 3 months. Just to be clear, after draining the main battery to 30-50%, I can leave the EVSE plug unplugged for the entire three months and this will not damage the main battery, correct? Also, is it advisable to put a trickle charger on the 12V battery?

[jlv]

I'd leave the battery with more SOC than that; more like 60-80% (as stated above). Definitely do not leave the LEAF connected to an EVSE.

If you have an ODB-II reader (for LeafSpyPro), disconnect it. Some of them continue to put a load on the 12V battery.