I know none of you dyed in the wool dino fuelled spanner monkeys are likely to be buying EV's any time soon and least of all something new
but I thought I'd put out a little public service announcement about the 40kWh 2018 Leaf 2, especially as you may have friends or family considering one.
In short - don't buy one or let someone you know buy one, it's a Lemon!
Or at least the battery is.
This is the new look restyled Leaf 2, which has been out for about a month now, with a claimed WLTP range of 177 miles - realistically 150 miles in summer, and a 40kWh battery.
I've watched a lot of review videos when it first came out and the reviews were very positive, and indeed in all ways except the battery it seems like a pretty nice car, and it had been on my shortlist of possible cars to replace the Ion in 5(ish) years from now once they were kicking around second hand... but it is well and truly crossed off my list now.
In short, Nissan totally dropped the ball on the battery, and it is going to come back to bite them, hard.
The battery on the Leaf's have always been their achilles heel compared to other EV's, because as well as falling behind other EV's for capacity and range, Nissan has never implemented any kind of thermal management system for the battery on the Leaf, and the new 40kWh model is no exception.
Most EV's have either ducted air cooled or liquid cooled batteries, because the battery needs to be kept within a comfy temperature range for optimal performance. If the battery gets too hot (over about 40C) rapid charging speeds have to be slashed to keep the battery from overheating, and if you're driving, acceleration would be reduced.
Conversely if temperatures are too low (below about 5C typically) you have to reduce rapid charging speeds because there is a risk of Lithium plating of the anode which causes permanent damage to the battery over time. So the colder the battery gets below about 5C the slower it will charge. This is all handled automatically by the onboard battery management system - as a driver of the car you will just notice your car charges slower in cold conditions, especially if the car hasn't driven much to warm up the batteries.
By the time you get to about -10C it will be charging quite slowly and most batteries cannot charge at all below about -30C.
For longevity of cells and balance of the pack as a whole it's also important to try to keep the temperature of individual cells as similar to their neighbours as possible. You don't want large temperature differentials between different cells as that will cause the cells to degrade at different rates.
The best possible arrangement is to have a liquid cooling loop that winds its way past all the individual cells, which can either cool the battery if it is too hot or heat it if it is too cold. This is what Tesla use, as well as the BMW i3, the Hyundai Ioniq, and even the Zoe. (Although I think the Zoe can only cool the battery not heat it) These systems work primarily during rapid charging to ensure maximum charging speeds but can also work during driving to keep the battery comfy if you were in really extreme environmental conditions.
Next best is forced air cooling which is used on my Ion. During rapid charging my Ion will take over the climate control system and switch a flap to feed it into the front of the battery pack where various ducts and fins spread the airflow out over the cells. At the rear of the pack is an extractor fan to suck the warm air out and exhaust it. So it both blows air in the front and sucks it out the back. Depending on the battery cell temperatures it will adjust the climate control to achieve an optimal temperature during rapid charging.
If they are hot the A/C runs full blast, if they are warm only the fan runs without the A/C, if they are too cold the fan won't even come on. (which has been the case lately!) So it can actively cool the battery but not heat it. That means that the Ion can rapid charge at maximum speed in hot weather without the battery overheating, but it will charge slower in freezing conditions as it doesn't have a battery heater like some other EV's.
During driving there is normally no airflow through the pack as the small power output of the motor doesn't dissipate much heat in the battery, but I believe that it can turn on the extractor fan in the rear of the pack while driving if it chooses to to provide some forced air cooling with ambient air.
The Nissan Leaf does...... none of the above. No active thermal management of the battery at all. Nada. Not any model of Leaf made to date.
They basically stuff a whole lot of tuna can shaped cells into a sealed box under the car and that's it. Not even any ventilation as far as I know.
They got away with it with the older models with the less dense batteries, but in the 40kWh model it has come back to bite them. Nobody is sure yet whether it's just a density issue, or a change in cell chemistry, but basically if you travel a long distance in the Leaf 2 and then rapid charge, then travel a bit more and rapid charge again, you'll get under half the charging speed you should get.
Maximum theoretical charging speed for a Leaf 2 is 50kW, but a lot of new owners are seeing only 22kW or less on the second and subsequent rapid charge, along with the battery temperature reading being near the red line, making the car basically unusable for any long distance travelling beyond about 200 miles, as you'll be waiting an eternity for your second rapid charge.
Basically the battery management system is severely curtailing the charging rate to keep the battery temperature from getting any higher. One user reported that the battery was reaching 50C when this was happening which is FAR too hot, not only that but there was a 13C difference between one part of the battery at 50C and another part at 37C showing that there was no airflow or ventilation in the battery pack design allowing hot spots to form.
Even at a full 50kW you'd still be looking at a good 45 minute wait to charge back up from empty to about 90%, with this issue people are seeing charging times on the 2nd and subsequent rapid charge of 1.5 hours or more, sometimes as much as 2 hours, which is completely unacceptable for a car that should "rapid" charge in under 45 minutes. Nissan have already added some weasel words to their advertising to say "dependent on battery temperature", but other than that they are not acknowledging any problem yet despite multiple sources online confirming it.
One example is Jonathan from Ecocars who I've mentioned before - he bought one for his own personal car and then "raced" it from Hinkley to Aberdeen a couple of days ago against an older 30kWh leaf and a 28kWh Hyundai Ioniq - those two cars took 12 hours including charging stops to do the 450 miles, the Leaf 2 took 15 hours due to all the additional time spent charging so slowly, despite having the biggest battery of the three....
He has been tweeting about it:
There are also a couple of long winded threads on speakev about this issue at the moment but I'll spare you the links because there is a lot of tedious bickering and disagreement in them due to a few people who have already bought one refusing to believe the evidence of what others have discovered.
What's even more of a concern is that the battery is overheating by the second rapid charge
in winter with ambient conditions of -4C to about +2C in the videos I've seen. What is it going to be like in summer ? My guess is that even the first rapid charge will be throttled in speed due to the higher ambient temperatures.
So in short if you just want to drive it around within a 70 mile radius of your home and charge at home, the Leaf 2 is probably a great car. If you want to travel any long distances that will require multiple rapid charging stops, especially with family onboard, forget it!
This is really disappointing, and although the mainstream media has not picked up on this yet, I'm sure they will soon, and I'm worried that it will give EV's in general a black eye when the "most popular" affordable EV that is available at the moment has a major design flaw and basically isn't fit for purpose as anything other than a local car, and is easily outclassed by the older shorter range model it replaces for long trips let alone other brands.
For example the 28KWh Ioniq which was racing it to Aberdeen is able to charge at 76kW on a suitable rapid, time after time without slowing down thanks to active cooling.
...... maybe more of an "open third rail" for trial purposes and easy modification