New Battery – 18 Month Check – Weak Cell?

It’s been 18 months and 22,000 miles since I had the main traction battery replaced in my LEAF. By and large it is fairing well. At 15 months old the battery was showing early signs of degradation.

Battery has increased capacity recently.

Interestingly in the last 2-3 months the battery has “recovered” some of the lost capacity I observed  and is now showing about a 5% reduction of capacity overall rather than the 7% I recorded earlier this year. That means the battery is losing about 3% per year on average which if the rate of degradation continues I will be at 15% capacity reduction at 5 years. A much better outcome than I experienced with the original battery.

That’s the good news. And now for the bad news….

Weak Cell? Click image to enlarge

Early sign of defective cell?

While the battery capacity trend is encouraging, I did experience a rapid loss of range recently near the end of a long journey where the battery was approaching the point where I would receive a low battery warning. I investigated the battery statistics when I got home and found that LEAFSpy Pro was indicating that cell pair #37 was weak. The car was at about 19% state of charge which seems reasonable for the 3.6 volts recorded. The reason the cell was flagged is because it varied from the rest of the pack by over 100 mV.

This is the first time since I got the car that I’ve recorded a weak cell. A single warning of this type does not mean the cell pair is definitely faulty, it could simply be a result of an imbalanced battery pack. However I will keep my eye on the battery cells each time I approach low battery warning.

Should this recur again with the same cell pair, I will ask for Nissan to do a thorough test of the battery.

What this means

The voltage of cell pair #37 had dropped to 3.611 volts. A battery pack is only as strong as its weakest cell. To protect the battery and its cells against damage, a single cell with a low voltage of 3.5V will prompt the car to shutdown. Hence the low battery and very low battery warnings the LEAF to let drivers know that their car needs a charge sooner rather than later.

The voltage of a cell can be used to approximate the charge level of the cell. This varies by the specific chemistry used in a Lithium Ion battery. The table below is an approximation of state of charge and battery cell voltage for Lithium Ion batteries in general.

4.2V – 100%
4.1V – 90% (LEAF full state of charge)
4.0V – 75%
3.9V – 55%
3.8V – 30%
(3.5V – LEAF Turtle/Shutdown)
3.3V – 0%

The LEAF limits state of charge between 17% and 90% of the cells theoretical capacity reserving some capacity to prevent damage at high or low states of charge. More reserve is present at low states of charge. (Source).

The LEAF battery cells have a theoretical minimum voltage of 2.5V below which the cell will become unstable when recharged, with the possibility of thermal runaway. The LEAF keeps well away from this theoretical low voltage state for both the long-term durability of the battery and for thermal safety.




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Trio of new Plug In Hybrids spotted in the wild, BMW X5, Honda Clarity and Mitsubishi Outlander.

It always interesting to spot a car for the first time in the wild. Did St. Patrick’s day come early as I found three PHEV’s in the clover today all plugged in and charging?

Here are some images of the trio that I spotted in Nashville today. Two of the cars are very new, they are sporting temporary tags.


Mitsubishi Outlander PHEV

Honda Clarity PHEV

Posted in BMW X5 PHEV, Electric Car, Honda Clarity PHEV, Level 2 EV Charger, Mitsubishi Outlander PHEV | Leave a comment

After one year, how my new battery is wearing

The original battery in my 2011 LEAF was worn enough to be replaced at 88,000 miles and I did end up replacing it at 99,000 miles. That was towards the end of 2016, 15 months later I checked to see how is the battery holding up.

Chart of how the LEAF battery has worn

There is some wear, about 7% reduction in total capacity since I purchased the new battery. The chart above shows the battery capacity expressed as Ampere Hours since May 2013 when I started keeping records until today. Prior to May 2013 there was no way for me to measure the battery capacity until I purchased a new app called LEAF Spy Pro. You can see where I replaced the battery in December 2016 when there is a big jump in the battery capacity.

No Wear for first 226 days / 8 months.

Lithium Ion batteries typically lose capacity at a faster rate when new and then one can expect the rate of loss to taper off as it ages. The odd thing about the new LEAF battery is that it lost no capacity for the first 8 months. This is highly unusual and one can only speculate why this is. I’m sure Nissan would not comment on the inner workings of their battery as it is proprietary.

My theory is that Nissan have added extra “hidden” capacity to the new battery packs and the battery management system (BMS) makes capacity available from the hidden reserve when needed, until there is no reserve left after which its business as usual.

Accelerated wear after first 8 months.

The old battery lost about 6% per year over its lifespan. The new battery has lost 4.7 ampere hours of capacity which is a rate of 4.3% per year. Sounds better than the old battery. However if I measure the rate of loss from 8 months of age until today the battery is losing capacity at a rate of 9% per year. Whoa!

This is partly explained since the period from 7/17/17 until 2/13/18 includes July and August the two hottest months of the year. Heat is not a friend of lithium ion batteries. So to be fair I compared a similar period from 7/1/13 until 2/1/14, however during the same hot months the old battery lost capacity at an annual rate of only 4%.  Hmmm, that does not sound good for the new battery.

There are many factors that contribute to battery wear.

I can only compare statistics for my new and old batteries which were used at different times and subject to different use patterns. While heat is major contributor to lithium ion battery wear, driving speed, acceleration and rapid charging can have a significant impact as well. I suspect that higher percentage of interstate driving in recent years has contributed to additional wear on the new battery.

No Better no worse

I don’t think it is fair to say the new battery technology is worse based on a sample of one and extrapolating wear rates, however it is fair to say the new battery is not any better than the old.

When I have had the new battery for 20 months I will be able to calculate a full year of continuous wear since the battery started to lose capacity at the age of 8 months.

Comparison to other electric vehicles

Competitive EV’s from Tesla and GM appear to fairing better than Nissan EV’s with less than 5% loss after 100,000 miles of driving. The technological differentiator is that Tesla and GM use active thermal management in their battery packs. This adds extra cost and complexity to their vehicles but does appear to be very effective at preserving their batteries.

LEAF’s in Europe fair much better than the southern states of the US. This is due to the lower temperatures in Europe. Active thermal management of EV batteries is necessary in warm and hot climates.


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First “Breakdown” at 111,000 miles

The day before a two week vacation I went out to the garage to go to work and the LEAF failed to start up. It turned on but stalled half way through its start up sequence. After several attempts to start the vehicle I started to wonder about getting it to the repair shop. I couldn’t even get it in neutral to allow a tow truck to pull it out of the garage. It was a poser.

I went inside to consider my options. I soon realized that modern EV’s are like computers on wheels; a reboot often resolves computer issues, the same might work for the car. I returned to the garage, disconnected the 12 volt battery and left the car for 30 minutes.

Upon reconnecting the 12 volt battery the car started normally and drove normally. I chose to take it to the local Nissan dealer for it to be checked over. The dealer retained the car for two weeks while I was on vacation. Diagnostics revealed no fault. It started for them every day without fail and has for me since I returned. The failure to start is still an unsolved mystery. This is the first time in 111,000 miles the car has let me down in anyway, and thankfully I was able to resolve the issue myself easily enough.

I carry tools with me to disconnect the 12 volt battery in case it fails me again away from home.

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Nissan agree to refund $1,000 of my recent repair bill !!

A few weeks ago my LEAF’s onboard charger failed and I was left with a $2,581 repair bill. This is just 8 months after replacing the battery. I decided to call Nissan Consumer Affairs and ask for out of warranty assistance.

I must have caught them in a good mood, they agreed to refund me $1,000. The check is in the mail. It should take about 5 weeks to get the check, but that’s fine. I’m relieved they were able to help with the cost.

Newton Nissan were instrumental in encouraging the corporate office to help me by sharing the number of service visits I have made over the last 6 years for both my LEAF and Altima. Newton Nissan do hold the distinction of being the number one rated Nissan dealer in North America.

Thank you Mr. Nissan.

Posted in Customer Service, Electric Car, Nissan LEAF, Uncategorized | Tagged | 4 Comments

Tesla Roadster spotted in Nashville

Tesla Roadster. Click to enlarge.

With only 2,450 Roadsters sold worldwide, it is very rare to see one in person. Anywhere. Never mind Nashville. It’s thought only 1,500 Roadsters were sold in the US. This is a collectors car for sure.

The car is tiny and very low to the ground. I don’t think I could manage to get into and out of the vehicle without help 🙂

The Tesla I saw in Nashville has Colorado tags with Stanford license plate holder. I saw one other Roadster in person while on a business trip to New England. Getting the car to Nashville must have taken some time. Roadsters do not have supercharger capability.

Roadsters were first sold in 2008 and their batteries are now getting to be old. Tesla have made available an upgraded battery pack that will boost the range of 244 miles to over 340, more than the longest range Model S which gets 315 miles. The upgrade to the battery costs $29,000. About the same price as a Model 3 after the $7,500 Federal tax credit. In a departure from Teslas’ exclusive use of Panasonic battery cells, the upgraded battery cells are made by LG Chem.

Tesla Roadster – Click to enlarge

Posted in Electric Car, SuperCharger, Tesla Roadster | 2 Comments

Another expensive out-of-warranty repair

One morning recently when I unplugged and started my vehicle I saw a warning lamp on the dashboard. I had seen this lamp once several years before after charging at a faulty public charging station. I wasn’t too concerned, the car drove fine. I power cycled the car when I got to work and the light went out and stayed out. Problem solved. That is until I tried to plug the car in to charge. It refused to charge even after several attempts.

Error codes from my LEAF

I have a program called LEAFSpyPro that can read the diagnostics codes from the cars computer. I saw 21 problem codes. Uh-Oh I thought, last time this light came on I got just two. With enough miles left to get me back home and onto the Nissan dealer I decided to drop the car off for repair after work.

When I got to the dealer, I shared the problem and showed the diagnostic codes to the service advisor. He asked me if I had replaced the 12v battery. No, never, was my response. Well hopefully that’s all it would be, he spoke of several LEAFs they had worked on that refused to charge and the root cause was a weak 12v battery. However the call I received the next day was not good, the 12v battery was just fine, the fault was with the built in battery charging assembly, estimated cost to repair $2,581. Unable to charge the car and with 19 miles remaining I had little choice but to get the car fixed.

Extended Warranty, good while it lasts. When I purchased the car new I bought an extended warranty good for 8 years or 100,000 miles. The car had been very reliable and and thankfully I didn’t need to use the warranty much. Six months after the warranty expired, this happened. That’s what you call bad luck. I knew that this was a risk but reasoned with the 100,000 miles of trouble free driving and only a year to take delivery of my Tesla Model 3 it should be an acceptable risk. After all I have done all the recommended maintenance. I’ve driven plenty of other cars without a warranty, and had pretty good luck, if you maintain a car it typically is faithful.

Other components in the LEAF such as the main drive motor and the inverter are also expensive assemblies. Driving a LEAF without a warranty is a financial time bomb, there are multiple expensive components that can fail, and few shops that are trained and certified to repair these EV components. With the high voltages in an EV fixing the car yourself without the expertise could prove fatal.

Good for just 100,000 miles.

It seems clear to me now that one should only drive a LEAF with a warranty. Once it gets to 100,000 miles, the car should be traded.

Fact or Myth? EV’s are cheaper to maintain. Err that would be a myth, despite fewer moving parts, the electrical components such as Battery, Charger, Inverter and Motor are all expensive.

Update 2017-07-13 Nissan agrees to refund $1,000

Nissan Consumer Affairs were able to arrange for a $1,000 refund for this repair given that it occurred close to the battery replacement just 8 months prior. See this post.

Posted in Electric Car, Level 2 EV Charger, Newton Nissan, Nissan LEAF | 5 Comments