long-term storage (months)

I'm going to be traveling for a few months, and wondered what I should do to best keep my leaf in good health. I've read in other threads here that the drive batteries should be at either 50% or 80% when I leave. I also have a battery maintainer that I use for other cars, should I use that on the 12V battery? The car will be in a garage, shaded from sun, heat, and weather.

Everything that you posted is correct. Maintainer on battery yes. 50% +/- on traction battery and your good to go.

caSteve said:

I'm going to be traveling for a few months, and wondered what I should do to best keep my leaf in good health. I've read in other threads here that the drive batteries should be at either 50% or 80% when I leave. I also have a battery maintainer that I use for other cars, should I use that on the 12V battery? The car will be in a garage, shaded from sun, heat, and weather.

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A few months, leave the main car battery charged to 60% and for the 12 volt battery, be sure it is a very small trickle charger that can reset charging. The Leaf will top off the battery every week, so a regular 12 volt charger can be fooled into a "finished' state this way if it does not reset and check the battery on its own.

Is it best to disconnect the 12V battery from the car while it's connected to the maintainer? If not, is it okay to connect the maintainer through the car's 12V "cigarette lighter" port? That's how I've done it on my other cars, but they're a different breed.

caSteve said:

Is it best to disconnect the 12V battery from the car while it's connected to the maintainer? If not, is it okay to connect the maintainer through the car's 12V "cigarette lighter" port? That's how I've done it on my other cars, but they're a different breed.

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Even disconnected, you want a maintainer for the 12 volt battery. If not to help extend the life of it. The 12V port is only powered when the vehicle is on ACC/Drive mode and you wouldn't want to leave the car like that for months.

i followed the suggestions posted here:

http://sfbayleafs.org/ev-resources/leaf-tips-tricks/how-to-store-your-leaf-when-going-on-vacation/" onclick="window.open(this.href);return false;

i put my leaf into storage on dec 1, 2014 with the traction battery charged at 40% and the 12v battery reading 13.0v. i turned off everything inside the car and removed the negative lead from the 12v battery. that's it. no battery charger attached.

i took my leaf out of storage on march 26, 2015, reconnected the 12v ground, and took the following readings: traction battery 39%, 12v battery 12.9v. furthermore most of my personal settings were still intact, including the radio's saved channels and the charging timer settings. oddly, enough, the only thing that changed was the clock on my dash had changed to 24-hour time while the clock on the computer's display stayed at the 12-hour display.

rhumbliner said:

i followed the suggestions posted here:

http://sfbayleafs.org/ev-resources/leaf-tips-tricks/how-to-store-your-leaf-when-going-on-vacation/" onclick="window.open(this.href);return false;

i put my leaf into storage on dec 1, 2014 with the traction battery charged at 40% and the 12v battery reading 13.0v. i turned off everything inside the car and removed the negative lead from the 12v battery. that's it. no battery charger attached.

i took my leaf out of storage on march 26, 2015, reconnected the 12v ground, and took the following readings: traction battery 39%, 12v battery 12.9v. furthermore most of my personal settings were still intact, including the radio's saved channels and the charging timer settings. oddly, enough, the only thing that changed was the clock on my dash had changed to 24-hour time while the clock on the computer's display stayed at the 12-hour display.

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Wow, was that cold storage or temperature maintained storage? Seems like it is easier to store the Leaf than I thought. Not so easy with a gas vehicle. :mrgreen:

I guess you could say it was semi-cold storage. it was kept in an unheated garage but here in vegas the temp was always above freezing.

I stored my 2014 LEAF in an attached, unheated garage on Dec 26, 2015. The garage is north-facing, in south central PA. It probably does not go as low as freezing in the garage, but does get very cold. Record cold could take the garage to freezing, perhaps. I attached a quality trickle charger to the 12 volt battery, and allowed the battery to remain connected to the car. The car was not plugged into my level 2 charger.

I returned to the car on May 9, 2016, removed the trickle charger, and checked the car over.

The battery status went from 71% to 64% over this 4.5 month period, a drop of 1.5% per month (assuming a linear drop). Range went from 58 to 52 miles.

I chose to leave the car at 71% charge status, as this was the first time I have tried this storage method, and dropping to zero was my primary concern. Thus, I wanted a bit of cushion, and decided that about 70% charge would do minimal damage. In the future, I'll probably leave it at 40% to 50% charge status for this same period.

I noted no problems with the car, and was happy with the results of this storage method.

I'm seriously considering a 2016 SV given the various incentives/rebates. One of my concerns is also long-term storage. The car would be stored in my detached unheated garage in the Seattle area from about October through April, while I am away enjoying my winter in the Valley of the Sun (Phoenix). Quite a snowbird habit I have acquired!

I have searched through the long-term storage threads here, and it seems the consensus is to leave the traction pack at about 50% SOC, then disconnect and/or use an automatic battery tender on the 12V. Sounds reasonable, and coincides with what other manufacturers suggest for their EVs, specifically the GM Volt. It also fits with what I know about Li-Ion batteries doing best when stored at half-charge, preferably in a cool environment, which my Seattle location fits perfectly.

Here is what I found in the 2016 LEAF manual on long-term storage (Page CH-4):

If the vehicle will not be used for an ex- tended period of time, charge the Li-ion battery using the long life mode once every three months. Do not operate the charging timer repeatedly while the charge connector is connected to the vehicle after the Li-ion battery charging is completed. Doing so may discharge the 12-volt battery. For additional information, refer to the long life mode charging method, in the “Charging timer” section of this manual. If the Li-ion battery becomes discharged, charge it immediately.

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Given that 80% is probably not quite that in absolute SOC, and that this would keep it simple for the average owner in all climates, I can see why it would be worded this way. If the DC-to-DC comes on every 5 days to charge the 12V, and potentially (not sure on this), the battery warmers to prevent freezing of the pack, a three month top up to 80% almost sounds like reasonable advice in the keep-it-simple approach.

Well, I wrote to Nissan for clarification, and if they had any slightly different advice for a 6-month absence. What I got back was (paraphrased):
1. Charge the vehicle to 100%.
2. Unplug the vehicle.
3. After three months, have a friend/neighbor drive the vehicle around a bit.
4. Go back to Step 1.
The author (from Nissan Vehicle Connected Services) also noted this was the only Nissan-approved recommendation for long-term storage.

This seems to go against the advice in the manual, as well as the annual Battery Information report card which has a line-item for "Long-term Parking with High State of Charge" (implying that condition is not healthy for the battery).

I would think it is best to follow manufacturer recommendations to maintain the warranty. It is disconcerting to see such mixed messages from both the manufacturer and the MNL community.

Personally, I am leaning in the direction of 50% and disconnect the 12V. Another idea I have thought of is leaving the vehicle connected to my OpenEVSE and using the RAPI interface to enable charging once every three months. I'd have to make sure that wouldn't discharge the 12V battery, or use an automatic battery tender to make sure.

Do the newer Leafs even have a "long life mode"? It was my understanding they did away with that feature after '13......maybe after '13(and before for sure) the only way to access 80% is to use the timer?......
Personally I'd charge the traction battery to 50-70% and then put the 12v battery on a tender that also incorporated a desulfication feature. I suppose you could also just disconnect the 12v battery(will save a few watts of electricity 24x7) but personally I think using a battery tender like I mentioned extends the life of the battery over just letting it sit, even without anything hooked to the battery. Oh if just letting the 12v battery sit I'd charge it full, unlike Li batteries lead acid is best left fully charged.

jjeff said:

Do the newer Leafs even have a "long life mode"? It was my understanding they did away with that feature after '13......maybe after '13(and before for sure) the only way to access 80% is to use the timer?......

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Yeah, I can't find how to set long-life mode despite searching the PDF 2016 manual for both "long life" and "80%"... plenty of mentions about the mode, but only says to see the Charging Timer section of the manual for instructions on how to set that mode. That section gives no clue.

Then again... that manual has a few typos in it, including:

... it is possible that the charger will snot start or the battery will not be charged to the level expected.

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Not sure if I should wear face protection at that point.

jjeff said:

Personally I'd charge the traction battery to 50-70% and then put the 12v battery on a tender that also incorporated a desulfication feature. I suppose you could also just disconnect the 12v battery(will save a few watts of electricity 24x7) but personally I think using a battery tender like I mentioned extends the life of the battery over just letting it sit, even without anything hooked to the battery. Oh if just letting the 12v battery sit I'd charge it full, unlike Li batteries lead acid is best left fully charged.

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My Honda Insight (2000) has an AGM battery. That did best left 100% charged and disconnected. My other car with a flooded battery did well on a Battery Tender.

Given the various errors in the LEAF manual, I'm wondering where the truth really is!

To GSHEPERD:

You should NOT buy a Leaf if you plan on leaving it in storage for 6 months out of the year. The car is not a static object that you can put away. The moment that a Leaf is made, the clock on the battery starts to tick. This car is made to be used daily. If you do not use the battery for 1/2 the year, you will (first) only get half of the useful life of the battery, and (second), the battery will deteriorate due to not being cycled, so you are really wasting your money....

I don't think the car will deteriorate due to 'not being cycled.' It will deteriorate due to age at the same rate it would if in use, though. If it's stored at roughly 50% charge, and the 12 volt battery is on a maintainer, it should do ok. Make sure the humidity in the storage area is low, though, or the mechanical components will develop a coating of rust. That will probably happen with the brake rotors anyway.

Hmm. I would expect the Li-Ion traction battery to have calendar aging, but not cycle aging during the time it is in storage. Lead-Acid, on the other hand, especially deep cycle, would atrophy from lack of cycling.

The alternative is to let agas engine sit for six months. Not ideal, though modern engines have shown to be fairly tolerant of that.

I have also considered having the car shipped south each year, although that adds its own hassle and expense, plus exposure the Phoenix heat in the Spring.

Perhaps I should pose this question on the general forum as to any snowbirds real-world experience with LEAFs?

gshepherd said:

Hmm. I would expect the Li-Ion traction battery to have calendar aging, but not cycle aging during the time it is in storage. Lead-Acid, on the other hand, especially deep cycle, would atrophy from lack of cycling.

The alternative is to let agas engine sit for six months. Not ideal, though modern engines have shown to be fairly tolerant of that.

I have also considered having the car shipped south each year, although that adds its own hassle and expense, plus exposure the Phoenix heat in the Spring.

Perhaps I should pose this question on the general forum as to any snowbirds real-world experience with LEAFs?

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I routinely leave my Leaf parked at the airport or office for up to 3 weeks at a time. I don't see measurable deterioration of the traction battery while parked (typically at about 60% charge) and the car turns on the DC-DC converter periodically so the 12-volt battery stays charged. Storing a Leaf in Seattle during the winter should be OK because it will not get cold enough to need the battery heater. If you park it at 50% to 70% charge, it would take care of itself (charging the 12-volt battery as needed). You could hook up a maintainer to the 12-volt battery, but that has its own risks of leaving it unattended for 6 months.

Gerry

LeftieBiker said:

I don't think the car will deteriorate due to 'not being cycled.' It will deteriorate due to age at the same rate it would if in use, though. If it's stored at roughly 50% charge, and the 12 volt battery is on a maintainer, it should do ok. Make sure the humidity in the storage area is low, though, or the mechanical components will develop a coating of rust. That will probably happen with the brake rotors anyway.

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There seems to be a lot of misinformation floating around the forum(s) about Leaf HV battery storage and optimal charge level; I think it is partly because of Nissan's original recommendations from a time when even Nissan didn't seem to know what was to happen to Leaf batteries in real-world usage, and partly because owners only see the consequences of their particular charge/discharge pattern.

Consider my Gen1 Leaf, built 5/12. It was one of hundreds that didn't sell in the Australian market because of a high purchase price, and sat in Nissan storage. In 2014 they were heavily discounted and sold in both Australia and New Zealand as new vehicles. At purchase (7/14) my Leaf had been in storage+transit for 26 months. AHr was 63.5 and SOH 96%. No significant evidence of age-related degradation there....

Based on what I read in this forum, my Leaf was purchased for local use only, and in practice I am never more than 10 miles from home, and usually less than half of that. It means I average only 30-35 miles/week despite use most days. Initially I was only charging a couple of times (to 80%) a month but seeing degradation despite little use. Unhappy with that, my reading led me to consider making use of (unsubstantiated) li-on battery "research" suggesting that storage at 40% or less was optimal. I decided to see what would happen if I restricted charging to the same level, 40%, and live within the range that offered.

So for the past year I have not charged past 40% but use the car daily, and charge every day or two (from about 20%). Result? Unforseen, but totally acceptable, NO degradation whatsoever in 12 months. In fact, after a P3227 software update, AHr has returned to 62.9 from 61.4, and SOH is back to 95% from 93%. In a 48 month old Leaf. Note that in moving to this strategy I found that degradation reliably kicks in above 41%. Also note that the very small range this level of charging offers, doesn't prevent my using the car in the morning, charging over lunch, then going out again. The level of total use makes no difference, the level of charging is critical.

Therefore I strongly support storage/charging at 40% or less.

I have had periods of up to 4 weeks where my Leaf sat in the garage unused (and note I never see 4 temperature bars, and a maximum of 6 bars for 1-4 weeks only mid-summer). I allow the Leaf to maintain the 12 volt battery, and leave the HV battery at 40% or slightly less. Battery readings on return are barely changed in every case, even at 4 weeks.

So it is my conclusion that the Leaf HV battery is VERY stable at or below 40% charge, and that owners should take every opportunity to maximise the time their Leaf is in this range, whether for storage or daily use.

Just out of curiosity, did you try charging to, say, 60%? 50%? You are saying that 40% minimizes degradation, and that 80% doesn't, but you don't seem to have any solid reason to believe that 40% is the actual threshold...

I do think that age degradation is probably also heat related, in that Leafs in very cool climates seem to suffer much less of it, while those that operate in just typically "warm" (not hot) climates experience what we think of as "calendar aging" even when not driven with 6 temp bars or more. So maybe the degradation is all from heat, but with a low threshold that falls within most of the climates in which the car is used. Maybe they should have named the car the "Snowflake" or maybe the "Spring." ;-)

LeftieBiker said:

Just out of curiosity, did you try charging to, say, 60%? 50%? You are saying that 40% minimizes degradation, and that 80% doesn't, but you don't seem to have any solid reason to believe that 40% is the actual threshold...

I do think that age degradation is probably also heat related, in that Leafs in very cool climates seem to suffer much less of it, while those that operate in just typically "warm" (not hot) climates experience what we think of as "calendar aging" even when not driven with 6 temp bars or more. So maybe the degradation is all from heat, but with a low threshold that falls within most of the climates in which the car is used. Maybe they should have named the car the "Snowflake" or maybe the "Spring." ;-)

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From Day 1 I kept a charging record, for about 7 months. For the first 3 months I charged to 80% plus 4 times to 100%. Degradation occurred each of these charge/discharge cycles.

In investigating a lower level of charging I first tried staying in a 30-40% range, doing a timed charge when SoC went below 30%. This sometimes resulted in an outcome under 40% and sometimes over. My recorded observations were that when the KWh level from charging exceeded 8.3, there was degradation on 31 of 42 charge/discharge cycles, and that when the resultant KWh was<=8.3, degradation occurred on only 2 of 74 cycles. At that time this 8.3KWh level corresponded to SoC around 41.5%-42.0%.

I regarded the above outcomes as a pointer to staying at or below 40%, and from then on did manual charging to achieve this. The pattern from then on was, no degradation unless the charging through oversight exceeded my goal. In those few instances, SoC rose to about 43-44%, and degradation occurred every time. I also once took the Leaf to the dealer for reversing sensors to be fitted, where they kindly did an 80% charge as a matter of course - AHr dropped 0.33 in just that one cycle. I now tape over the charge port when the car goes for a service...

My current strategy is for a 70min timed charge after going below LBW, which results in SoC mostly between 36%-39%. it's a safe level such that I now don't bother monitoring all the time.

So, is 40% an exact threshold? Not exactly, but close enough for me

I like your notion of "calendar ageing" perhaps being all from heat - my Leaf runs more or less entirely in a 10C - 24C range, and doesn't do any all-day sitting in the sun, so I'll vote for Spring!

Wow! Great input, and the thoughtful replies give me a much better idea of long term storage.

So with the datapoint from hieronymous, I can see that 1) using LeafSpy and keeping a charging log can reveal unexpected patterns and potential correlations, and 2) the oft-recommended "store at 30-40% SOC" for Li-Ion battery cells still seems to apply to the LEAF despite Nissan's official procedure in the owners manual.

How interesting to consider that one could extend the life of the LEAF battery far beyond normal expectations by limiting charging to 40%. In a way, it would be like living with a degraded pack day-to-day but having the option for higher charges when you needed it.

I plan to have my detached garage rebuilt this year, so with some insulation, the winter temps will likely be in the 0C to 10C range. I had also planned to extend the house hydronic floor heat to the garage slab which could keep the space above freezing even when we get one of the cold snap weeks down below freezing. Between that, remote home automation access, and a helpful neighbor, I should be set.