On the MyNissanLEAF.com owners forum two Pheonix, Arizona LEAF owners have reported losing 15% of their battery capacity after just over a year of ownership. The owners share the following. They both live in the Pheonix area and they both charge their vehicle to 100% capacity most of the time.
Forum user ‘azdre‘ reported the degradation occurring on the vehicles battery gauge on the dashboard at 17,000 miles after 14 months of ownership. Another forum user ‘bturner‘ reports the loss of a capacity bar on his/her LEAF at just 13,000 miles and 12 months of ownership.
Nissan have estimated battery degradation will reduce total capacity to 80% after 5 years and 70% after 10 years at which time the owner may want to replace the battery pack. Nissan’s advice to owners is to charge to 80% whenever appropriate to extend the battery pack’s useful life.
The two forum users experiences show a 1% per month battery capacity degradation. At this rate they may only have 40% capacity left after 5 years. The rate of degradation is highest when the battery is new and slows down over time, even so they are on track to overshoot Nissan’s estimates by a wide margin. It is speculated on the forum that the combination of heat and maintaining a high charge rate for an extended period may have contributed to the battery capacity losses reported. I imagine Nissan will keep a close eye on these reports. If similar reports increase they may have a technical and/or PR problem on their hands. I’ll be interested to see how Nissan handle these reports, especially if there are more.
As delivered from the dealer the default charge percentage is 100 and requires the user to setup a charging timer in order to utilize the 80% charge level. I have spoken to some LEAF owners who where not aware of this recommendation for several months after taking delivery. Nissan could do more to educate their customers about charging strategies. They do a great job at the time of purchase of explaining and making the purchaser sign an agreement acknowledging that capacity loss is not covered by the battery warranty. Why not provide charging advice and instructions at delivery?
The LEAF traction battery warranty does not cover gradual capacity loss, however Nissan do not define what ‘gradual’ means. Not that it matters, Nissan have indicated the warranty covers only loss of vehicle power due to a battery issue. Reduced capacity does not mean reduced power, just reduced range. I feel Nissan should put boundaries around what an acceptable battery capacity loss rate is, and provide pro-rated warranty coverage when a battery falls outside of the expected parameters (much like their tire or 12 volt battery warranty). A pro-rated warranty is a good way for Nissan to share the risk and costs of rapid battery degradation with the owner. As early adopters of this new technology we know that unexpected failures and costs may occur, but it would be nice if Nissan would offer to meet us ‘half-way’ if such eventualities occur.
It is postulated on the forum that the critical factor isn’t charging to 100% but how long the battery remains at a 100% after charging is complete.
Update 2012-07-21 – Nissan do Something!!
Nissan are examining 6 LEAF owners vehicles in Arizona and providing loaners until the tests are complete. To learn more view the following article/video by an Arizona TV station.
What I will do about it
I charge to 100% about 2-3 times per month when I expect to do longer trips. I will change my practice of charging as soon as I get home and program the vehicle to charge early morning on the days I need a 100% charge. This should reduce the time the car sits at a 100% charge level. When charging to 80% I will continue to opportunity charge throughout the day or when I arrive home, there is no evidence that opportunity charging reduces battery life at recommended charge levels.
Update 2012-05-18: A third Pheonix LEAF owner looses a capacity bar.
A third LEAF owner (forum handle: ‘turbo2ltr’) who also owns a ‘GID Meter’, initially reported he had lost 19% capacity from new, but had at that time not lost a capacity bar. A ‘GID meter’ measures the energy stored in the battery on an absolute scale, the meter is an unofficial tool developed by LEAF enthusiasts.
Well the capacity bar disappeared in the last few days making him the third Arizona owner to loose a significant amount of battery capacity in just over one years ownership. He too charges his vehicle to 100% daily. Read his account here.
Update 2012-05-20: Make that five owners in Arizona.
Today two more LEAF owners in Arizona reported battery degradation. The forum users are ticktock and Volusiano. This is becoming a concern, both owners have had their LEAF’s under a year. Volusiano charges to 80% most of the time and never saw the battery temperature gauge go above 7 bars. Here in Tennessee I’ve seen 7 bars occasionally for battery temperature during the hot summer last year when we reached 107 one day at my house.
One wonders if the record high temperatures experienced in Arizona last August cooked a number of batteries. The owners manual cautions against storing a LEAF at 120 degrees or more for more than a 24 hour period. Clearly if the record high was 117 owners should have been OK. However I wonder what temperatures were in direct sunlight when vehicles were parked, not just temps in the shade? Pheonix averaged 109 degrees last August, today’s temperature is 102!
Volusiano kept his/her LEAF garaged and made ventilation alterations to the garage to keep it cooler.
Update: 2012-05-22 Make that six owners who report having lost capacity.
The forum user this time is mark13..
Update:2012-05-27. Seventh owner reports battery capacity losses.
Another LEAF owner in Arizona reported battery capacity losses, The forum poster is known as leafkabob. The suitability of the LEAF in hot climates is now questionable. One assumes only a fraction of LEAF owners are posting or even reading the forums, so the number of lost capacity bars maybe two or three times as many in the Pheonix area.
Several of the owners in the area have meters that measure energy stored in battery and have seen a drop off during the past year at full capacity which would rule out a software bug in the battery capacity dash display. Some have speculated on the forum that the LEAF’s software may limit battery capacity purposefully during hot weather to protect the battery and the losses observed maybe seasonal only. Either way, a 15% loss in range in the first year is a hard pill to swallow.
Update 2012-06-20: More reports have come in from Arizona and one from the Dallas TX area. The tally now stands at 12 Arizona Owners and One Texas owner having reported battery degradation directly on the forum. It is also reported that 3 other Arizona LEAF owners who do not participate in the mynissanleaf.com forum have also lost a capacity bar. At least 17 owners in hot climates have now experienced loss of battery capacity. Several others have measured their capacity and are anticipating the losses to be reflected on the battery capacity gauge soon. Nissan are reported to have issued a statement regarding these losses, but it merely downplays the whole affair as insignificant.
Update 2012-07-01: The count continues to increase, more concerning is that several owners are now reporting a second capacity bar loss, forum poster turbo2ltr provided photographic evidence of his dash display. Forum poster Volusiano has taken it upon himself to provide a summary of all reported losses, with dates and locations. The latest tally is 16 in Arizona and 3 in Texas.