Weird glitch with LEAF while driving – No fault found

I was driving home recently with the family from Texas Roadhouse when the LEAF made a beeping noise and I noticed warning lamps on the dash. One warning lamp was the EV System Warning Lamp. In addition to the warning lamps I also noticed that the distance to empty gauge was showing dashes. Dashes in place of miles normally occurs when the traction battery has a very low charge. However the car was 2/3rds full and it continued to show 2/3rds full after the dashes appeared.

EV System Warning light and loss of estimated range after glitch. Click to enlarge

The car drove normally. After we got home I restarted the car and everything was normal. Over the next day or two I did notice that the LEAF was more pessimistic about the range remaining compared to its normal over optimistic estimates. The estimates returned to normal within 36 hours. It seemed like a computer in the car responsible for estimating range rebooted itself and reset settings while being driven.

Not knowing what could cause such a glitch I did take it by the dealer for diagnosis. The car did register a fault code the dealer was able to read which indicated erratic CAN voltage. The dealer could not reproduce the fault and cleared the error code.

3G telematics to blame?

Ever since Nissan replaced 2G telematics units with 3G telematics units many customers have complained of random CAN errors. In some cases this has been traced back to low 12v battery voltage causing an array of random and erroneous error codes.

Everything back to normal, except the low distance to empty estimate. Click to enlarge

The consensus in the LEAF community is that the 3G telematics unit consumes more power and the 12v battery has more of a challenge keeping up with demands from the cars electrical systems. I did use the cars remote A/C pre conditioning both prior to heading to the restaurant and prior to heading home. It’s quite likely that multiple requests back to back may have weakened the 12v battery. The 12v battery is just over 1 year old so I doubt it has gone bad. If I get more errors like this, I’ll opt for a larger capacity 12v battery that will not run low so easily.

The good news is that the car did not breakdown or lose power at any time. It seems the error was spurious. The LEAF after 123,000 miles has yet to leave me stranded at the side of the road. It has been a very reliable car, all other cars I’ve owned previously have broken down at least once. EV’s are remarkably reliable vehicles.

Posted in Electric Car, Nissan LEAF | 1 Comment

Not glad to see this Tesla Model 3 blocking a charging space.

Model 3 owner blocking a ChargePoint charging space. Click to enlarge

In Tennessee a Tesla Model 3 is still quite a rare sight, I’ve only seen three in the wild in the last year. You’d think I’d be glad to see another today. Not so much, the Model 3 owner thinks its OK to park in a charging space and not plug in and charge. Not cool. When Fossil cars do this we call it ICEing. Not sure what to call this other than inconsiderate.

What motivated this driver is unknown, it could be laziness, or because this site charges a fee, it might be being too frugal. Either way its wrong.

Posted in ChargePoint, Level 2 EV Charger, Tesla Model 3 | Leave a comment

Tesla’s route planner “gas savings” strongly biased towards Model S and X vehicles.

Model S Gas Savings round trip to Florida

A few months ago Tesla released a route planner to assist prospective owners determine which vehicle would best meet their needs. Having played around with the planner using various vehicle types it seemed the Model S and X vehicles have a distinct cost advantage over the Model 3 for long trips. According to the trip planner the model 3 costs almost as much as a gas vehicle to drive. Saving just $26 on a round trip to the beach, while the Model S saves $142.

Model 3 estimated gas savings round trip to Florida

While Model S and X do enjoy free supercharging and Model 3 owners pay per use I suspected the planner was slanting the results to encourage prospective buyers to purchase a Model S or X.

 

So instead of planning a long trip, I planned my daily commute. The planner does calculate your monthly gas savings for the commute and correctly identifies that supercharging is unecessary. For all three vehicle types the monthly savings should be pretty close. But it isn’t. For a Model S 100D vehicle it calculates my monthly commuter savings to be $214 per month. This is close to the $180 per month savings I record for my LEAF. For the Model 3 the estimated monthly commuter savings is reduced to just $39/month. This is clearly wrong, the cost of electricity at my home is constant. The Model 3 should enjoy even bigger savings, its a smaller more efficient car than the Model S. Interestingly it does not matter which S or X vehicle you choose, the savings are identical $214/month. I would expect the S to be slightly more efficient than the X. This planner does a poor job of calculating savings based on vehicle type.

Model S commute savings to work

Calculated commuter savings for Model 3

The Tesla trip planner should only be used to give an idea of how many SC stops you need to make for your long trips. The gas savings calculations are biased and flawed. Ignore them.

Posted in Nissan LEAF, SuperCharger, Tesla Model 3, Tesla Model S, Tesla Model X | Leave a comment

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.

BMW X5 PHEV

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.

 

Posted in Electric Car, Nissan LEAF, Review | Leave a comment

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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