Leaving LEAF unatended for months

I will not be using my LEAF for a fewmonths, is there any action I should take? disconnect from charger?
help/advise here, I don't want to ruin the battery left unattended.

JC :?:

joecaymin said:

I will not be using my LEAF for a fewmonths, is there any action I should take? disconnect from charger?
help/advise here, I don't want to ruin the battery left unattended.

JC :?:

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The owner's manual has this to say:

If vehicle will not be used for long period of time:
— NISSAN recommends charging with long life mode.
— Charge once every 3 months.

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So, charge it up to 80%, and don't worry unless you're going to be longer than 3 months. If you are, get someone to plug it in at least that often.

I read an interesting article at Battery University. It says "For long-term storage, manufacturers recommend a 40 percent charge. "

You can read the whole article here:
http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

While they are talking about Li-ion batteries, it might refer to cell phones, lap tops, etc.

Dennis

Orphan Leaf June 27, 2011. Still using trickle charge....

That article has a lot of good information around temperature and charging limits (even though we're talking about very different capacities with the Leaf). The general consensus in the forum is to keep the Leaf around 50% charge (and NOT plugged in) for long-term "storage". The big picture is: don't keep it above 80% or below 30%. It would be interesting if some of these folks in this situation post charge status "updates" periodically (like every couple of weeks or so) to see what kind of self discharge rate the battery pack actually displays; I assume you can get this via CarWings (although it may shut down after a period of non-use?).

I had mine charged fully before I left for 7 weeks in Hawaii. It worked fine when I returned. I have no idea if the car was harmed. It works fine.

Stanton said:

That article has a lot of good information around temperature and charging limits (even though we're talking about very different capacities with the Leaf). The general consensus in the forum is to keep the Leaf around 50% charge (and NOT plugged in) for long-term "storage". The big picture is: don't keep it above 80% or below 30%. It would be interesting if some of these folks in this situation post charge status "updates" periodically (like every couple of weeks or so) to see what kind of self discharge rate the battery pack actually displays; I assume you can get this via CarWings (although it may shut down after a period of non-use?).

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Excellent write-up, I would just add that CarWings will not update if the Leaf was not driven once in two weeks. This came up in another thread, and it's something to keep in mind while you are traveling.

If I was to go on a six months long trip, I would charge the Leaf to seven bars. Unplug it, disable timers, make sure that everything was turned off and the car was protected from sun and heat. I would check CarWings once or twice during the first two weeks to see if the Leaf was not losing charge unexpectedly fast. There will be probably about three bars left upon your return.

Since you will be gone for such a long time and we don't know what the actual self discharge rates are, it might be a good idea to have a friend or a neighbor plugin the car once a month to see if there is at least one solid blue light visible behind the windshield. If there is only one blue light blinking, I'd instruct them to leave the Leaf plugged in for about an hour.

I hope your trip goes well, and please report back to the forum if the Leaf behaved while you were gone

Let your neighbor drive it. No LEAF should be left alone...

Run it down most of the way. Then set the timer to charge 30 minutes per week to 80%.

smkettner said:

Run it down most of the way. Then set the timer to charge 30 minutes per week to 80%.

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Interesting idea! How about leaving the Leaf with 3 bars and setting an 80% timer to 10 minutes per week? That would add about 2kWh or about one bar per month to the pack. I would expect self discharge losses to be less than 8% of rated capacity per month, and the Leaf should be about half full after six months.

TangoKilo said:

Let your neighbor drive it. No LEAF should be left alone...

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Or put it on a flat bed truck and send it to me. I'll be happy to drive it while you don't need it.

I have experience with that. My Leaf arrived in late Dec. 2011, I was scheduled to travel Jan-Mar 2012, so I asked the dealership what I should do? Since it was winter, they recommended that I charge it to 100% and leave it plugged into the L2 charger (GE WattStation, btw) with the charging timer set to charge everyday (if needed). They said this was best because if it got cold, the battery could keep itself warm. Anyway, I checked using the Internet every week while I was away, although being in my garage, sometime it could not communicate with the Leaf. In those cases I would ask my wife (via Skype) to check on the Leaf. After about 6 or 7 weeks, when she checked the Leaf, there was no power, that is, she could not turn it on. What happened was the 12 volt battery had gone dead. Apparently, the 12 volt battery gets charged only when the Leaf is on and not charging the Li batteries, or via the solar panel. Anyway, when I returned about a week and a half later, I did what they old me and jump started the Leaf 12 volt battery using my Ford Ranger. Then I took it to the dealership to be checked out and get the Nissan free software/shield upgrade, no problems with anything detected. I had only had a chance to drive it once before I left on the trip, and only for about 20 or 30 miles, so maybe the 12 volt battery had never been fully charged, I don't know.

Based on that experience, I asked them if, in the furture, I need to leave the car idle for a long time, what should I do, should I put the 12 volt battery on a trickle charger like I do my boat battery? No one had an answer at the dealership, or the Nissan help line either. I guess they didn't anticipate that situation when they designed the Leaf?

If the 12 volt battery goes dead, the charger/charge timer will not operate. Seems to me they should set things up so that when the Li batteries are not charging, even while hooked to the L2 wall unit, some charge could be provided to the 12 volt battery to keep it going. When the Li batteries are hooked to the L2 charger, it apparently (what I was told by Nissan) disconnects a DC-DC converter between the Li and 12 volt batteries that charges the 12 vlt when the Leaf is operating.

Something of a conundrum/cathc 22...

Sounds like you should tell your dealer to look at what the owners manual says. No catch, no conundrum. Just do what davewill said on the previous page. Charge to (at most) 80% and leave it unplugged. The high voltage battery will be good for many months, and will keep the 12v battery charged. If plugged in it will not keep the 12v battery charged, as you discovered. And as for keeping it topped off at 100% -- <shudder!>

Ray

CHLPatent said:

I have experience with that. My Leaf arrived in late Dec. 2011, I was scheduled to travel Jan-Mar 2012, so I asked the dealership what I should do? Since it was winter, they recommended that I charge it to 100% and leave it plugged into the L2 charger (GE WattStation, btw) with the charging timer set to charge everyday (if needed). They said this was best because if it got cold, the battery could keep itself warm.

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Truly, your dealership gave you the absolute WORST advice possible on this subject. Here are some things wrong with it:

1) When it is OFF and plugged in, the LEAF draws significantly more current from the 12V battery than when it is unplugged.
2) The LEAF ONLY charges the 12V battery in that situation while it charges the traction battery. Since your traction battery was charged to 100%, it would never charge the 12V battery.
3) Storing the LEAF with the battery at 100% causes permanent battery degradation to occur faster than at a lower SOC such as 60%.
4) Discharging the 12V battery to dead and leaving it in that results in permanent damage to the battery.
5) Their description of why it was "best" is simply wrong, even if you live in Minnesota and have the cold-weather package. Why? Because nothing works once the 12V battery dies, regardless of the temperature.

In other words, their advice ENSURED that your 12V battery would die as soon as possible and that your traction battery would sustain as much degradation as it could while you were away.

CHLPatent said:

Seems to me they should set things up so that when the Li batteries are not charging, even while hooked to the L2 wall unit, some charge could be provided to the 12 volt battery to keep it going. When the Li batteries are hooked to the L2 charger, it apparently (what I was told by Nissan) disconnects a DC-DC converter between the Li and 12 volt batteries that charges the 12 vlt when the Leaf is operating.

Something of a conundrum/cathc 22...

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Agreed. But it seems there is another solution available to Nissan: Design the LEAF so that it charges the 12V battery from the traction battery every day or so while plugged in BUT DON'T CHARGE THE TRACTION BATTERY AT THAT TIME. The traction battery can continue to get charged by whatever schedule is set up and there can be an override function to stop charging the 12V battery if the traction battery is below 20% or so.

Nissan really needs to come up with some form of "storage" mode for the LEAFs that dealerships and owners can use that maintains the health of BOTH the traction AND the 12V batteries. I'm thinking it would require the car to be charged above 70% and then unplugged. It would then discharge the traction battery to around 70% and then maintain the 12V battery daily or so from the traction battery until the traction battery slipped below 20%. After that, open the contactor and let the 12V battery be damned.

They essentially already do. Just leave it unplugged and the pack charge will remain essentially where it was left for MANY months, and will charge the 12volt battery every 5 days to keep it healthy.

RegGuheert said:

Nissan really needs to come up with some form of "storage" mode for the LEAFs that dealerships and owners can use that maintains the health of BOTH the traction AND the 12V batteries.

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TomT said:

They essentially already do. Just leave it unplugged and the pack charge will remain essentially where it was left for MANY months, and will charge the 12volt battery every 5 days to keep it healthy.

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They do have that mode. While I agree that it will keep your 12V from being fully drained, I will disagree that it will keep it HEALTHY. The testing that I have done indicates that the 12V battery SoC is maintained at about 50% or below and is never fully recharged, meaning that the lead sulfate that forms as a result as the discharge reaction has plenty of time to harden, thereby reducing the capacity over time. By not ever fully charging the 12V battery to 100% SOC, the battery will eventually die. Like most things, this death will occur much more rapidly in a hot climate.

RegGuheert said:

1) When it is OFF and plugged in, the LEAF draws significantly more current from the 12V battery than when it is unplugged.

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I am going to withdraw the "significantly" part of that statement for the time being. Here's why:

I am starting a "plugged-in" 12V battery test this morning and the first thing I did was to measure the resting voltage with the car NOT plugged in. It was 12.49V. Then I plugged in the vehicle and let it rest for about one hour to find the resting voltage. Plugged in resting voltage was 12.46V. Since the drop was possibly due to a combination of a reduced SOC and an higher load current, I then did a third test by pulling out the plug again and allowed it to settle. Unlike plugging in, unplugging does not perturb the car (beeping and flashing, etc.), so the SOC should not be affected. After resting for over 30 minutes, the voltage only rose to 12.47. The conclusion is that there is an additional current drawn from the 12V battery when it is plugged in. This current is enough the reduce the battery terminal voltage approximately 10 mV (+ or - 10 mV).

After a few days, I will be able to determine how much more quickly the battery voltage drops while plugged in than what I measured in my previous test with the LEAF unplugged. In that test, I observed the 12V battery voltage dropping at a rate of about 25mV/day.

A clamp-on ammeter would be a better judge of 12v draw than the resting voltage.

smkettner said:

A clamp-on ammeter would be a better judge of 12v draw than the resting voltage.

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Agreed, but what I'm really after is voltage drop over time so that I can estimate how quickly the SOC is dropping. (We don't know what the capacity of the battery is!)

TomT said:

They essentially already do. Just leave it unplugged and the pack charge will remain essentially where it was left for MANY months, and will charge the 12volt battery every 5 days to keep it healthy.

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I've done this a couple of times with no issues (for a couple of weeks, not months).

This discussion begs the question of what to do for long term storage of a LEAF in extreme cold weather, with temperatures below -4ºF (-20ºC). I guess I'd be inclined to put it at about 50%, plugged-in, charge timer set to charge about 15 minutes a day with an 80% limit. That way the 300 W battery heater could run as needed and the 12 V battery would get charged up during the daily charge cycle. But once the battery hit 80% the 12 V battery would no longer get charged.

Another possibility would be to charge to 80%, leave it unplugged and let the battery heater draw the traction pack down as needed. I believe that it shuts off when the traction pack hits 30% though.

Any thoughts?

I'm glad I don't have to deal with this: my garage doesn't go below freezing and I don't expect to need to leave my LEAF unused for more than ten days or so.