Ever since the Nissan LEAF went on sale in the UK in March 2011, we’ve seen more and more CHAdeMO DC quick charge stations appear across the country, first at Nissan LEAF dealers and then at motorway rest stops and even shopping centres. Capable of recharging a car like the Nissan LEAF and Mitsubishi i-Miev from empty to 80 percent full in around 30 minutes and from there to 98 percent full in another 20, locations with CHAdeMO quick charge facilities have quickly become natural waypoints for anyone with a compatible EV wanting to make a trip beyond the range of a single charge.
Historically, many of these public charging stations have allowed users to first charge to 80 percent full, then top their car up to between 90 and 98 percent, depending on the car and location, but over the past few weeks we’ve heard from EV drivers concerned that they can no-longer use CHAdeMo quick charge stations as they thought they could.
Most of the problems appear to be centred around newly-installed quick charge stations, but in recent weeks we’ve heard from users who have regularly used a particular quick charger, manually overriding the charge or time limit to achieve the maximum state of charge for the next leg of their trip, only to discover that suddenly the charging station will not let them go beyond 80 percent full.
With some quick charging stations being more than 60 miles apart, owners of quick-charging EVs were understandably shocked: without the ability to increase their cars’ state of charge above 80 percent full, some drivers found they couldn’t make trips they once were able to.
As with any other early-adopter community, there’s been a lot of discussion about the cause of the problem, with some pretty heated discussions taking place on owner forums and social networking sites. Some drivers have blamed Nissan directly, claiming the automaker is limiting quick charging to 80 percent to avoid costly warranty claims. Others claimed the charging station providers were restricting charging to 80 percent to reduce the amount of time drivers could stop at the quick charge station, while another group claimed the problem lay with revisions to the Nissan LEAF itself.
In order to fully understand the problem and because all of the reports we’d heard involved the LEAF, we reached out to Nissan for some help. At the time of writing, Nissan says it is still investigating the problem, but it does have some ideas as to what is going on. Here’s what we’ve learned from Nissan so far, along with some observations from high-mileage LEAF drivers.
Under-estimation of charge levels
Nissan says its engineers have discovered that the charging meter on some quick charging units are overly optimistic about the actual state of charge of the car connected to it, meaning that the charging station thinks the car has a higher state of charge than it really does.
“This can mean that a LEAF customer has a lower level of actual charge than is stated on the charging unit,” said Nissan in an official statement to Transport Evolved earlier today. “We believe that this may be technical error with the charging unit and it is currently being looked into by the European technical team and the charging infrastructure supplier DBT.”
In every Nissan LEAF we’ve ever driven — regardless of the year or model — we’ve observed this phenomenon and don’t believe this problem to be a new one. In fact, other EV drivers around the world, including Plug-in America’s Chief Science Officer Tom Saxton, have already investigated the problem thoroughly.
Writing on his own blog back in September 2012, Saxton describes the problem in great detail and even suggests that charging station manufacturers be made aware of the issue as soon as possible. Further, he advises that drivers ignore the reported state of charge as displayed on quick charge units, relying instead on the state of charge reported within the car or from an after-market state of charge meter.
A known software problem
If the first part of the problem wasn’t enough, Nissan admits that it has discovered some newer rapid charge units — specifically ones made by DBT — have been inexplicably set to prohibit charging beyond 80 percent full. In our lengthy discussions with Nissan technical staff and its press team, the Japanese automaker has gone to great lengths to state that it did not request or condone this practice.
“On the newer units, the function to override the automatic 80% charge level cutoff has been deactivated,” Nissan confirmed to us in an email earlier. “In order to charge to above 80% customers now have to disconnect and reconnect the charger after the cut off. Nissan is investigating why this has been changed and will review any potential actions with DBT.”
In other words, Nissan says that drivers who disconnect their cars after the charging station has reached the 80 percent cutoff point and then reconnect them back up should be able to charge their cars beyond 80 percent full. We’ve not had a chance to test this theory yet, but we’ve certainly replicated this behaviour in the past at stations limited to an 80 percent initial charge.
The final piece of the jigsaw seems to lie at the feet of new EV owners who are experiencing the joys of quick charging for the first time. Since every type of charging station and quick charging unit is slightly different from another, there’s a great deal of confusion from drivers who do not fully understand how the quick charge stations work, or who make mistakes — like leaving their car on — when attempting to quick charge.
The solution here of course is better driver education, both from Nissan itself and from charging station providers. But for now, here is our advice to anyone planning a long-distance EV trip which involves the use of a DC quick charge station en-route.
- Always check ahead to see if the unit is functional. Some charging providers — like Ecotricity — have a regularly-updated map detailing which charging stations are working and which ones aren’t. Other sites can be checked using something like the Open Charge Map. Finally, a quick search on twitter for #UKcharge (for UK residents) can also help identify charging stations which aren’t working.
- Always turn your car off before plugging in to a quick charge station. If you’ve got a Nissan LEAF, you can activate climate control to keep the car warm remotely while charging using the Carwings telematics service on your smartphone or PC.
- Charge to 80 percent full, then when the charging station stops charging, disconnect your car and (if you need more charge) reconnect it.
An ongoing investigation
Talking to Nissan this week, it’s become clear that the automaker — which has a clear intention to continue its support and rollout of electric car charging infrastructure across the world — wants to resolve this particular issue with its charging partners and charging station manufacturers as quickly as possible.
But perhaps the biggest challenge for Nissan is to quell the frustration of its growing customer base of LEAF drivers, many of whom blame Nissan for the problems, regardless of where fault ultimately lies.
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