Advances in regenerative braking in electric cars have allowed the advent of so-called “one-pedal driving” in which drivers can now simply press and lift off their foot from the “gas” pedal — let’s call it the accelerator — without having to use the brake pedal at all outside of emergency braking.
While the car is being slowed by the reversing electric motor, energy from the vehicle is captured and sent back to the battery, and it generally now activates automatically when the accelerator is released.
Nissan were one of the champions and pioneers of this technology with their e-pedal, taking existing regenerative braking technology that was common in many hybrid cars and making it more effective, and even safer. Great as the e-pedal has been for most, problems remain and there have been some people complaining that their regenerative braking function has not been working as it should do.
Background: How Should the E-Pedal and Regenerative Braking Usually Work?
The Nissan e-pedal was pretty groundbreaking technology when it was first launched onto the scene. Regenerative braking had previously worked by applying the brake and the regenerative force gathering and returning energy to the battery. However, some criticized this approach because it seemed to make their brakes spongy and less responsive overall — not something you want in an emergency situation.
Nissan’s e-pedal changed all that, by shifting the regenerative braking to work instead as a function of simply taking one’s foot off the accelerator rather than applying it to the brake. The regular hydraulic brakes would still be there for emergencies, and for those situations if and when regenerative braking wouldn’t bring the car to a stop when on a lower setting.
With the e-pedal in play, drivers simply press on the accelerator to move their Nissan Leaf, and then lift it off again to apply the brake. The regen system gently brings the car to a halt, making use of its cameras and sensors to ensure that proper and safe distances are maintained between the Leaf and other vehicles.
Benefits of Nissan E-Pedal
The best thing about having a one-pedal driving system like the e-pedal is that it makes driving in city traffic far more agreeable. Many electric cars today are still bought for use in cities and other built-up areas since many models don’t have the range for people to confidently purchase them as long-distance vehicles — though that picture is changing fast. Therefore, the e-pedal has been a game changer for many drivers who previously had to do the uncomfortable dance in traffic, shifting their foot from accelerator to brake, back to accelerator, back to the brake, and so on. It was even worse, of course, for those driving manual transmission cars who had to factor in the clutch and gear shifting, too!
As for the regenerative braking aspect, the e-pedal allows easier and more comfortable access to regen braking, without having to actually apply the brakes themselves. The electric motor seamlessly flips into reverse motion, thus allowing recaptured kinetic energy to be redirected back towards the main battery. As things stand at the time of writing, the technology isn’t anywhere nearly powerful enough to recharge significant amounts of range back into the battery during any journey, but in those situations where every half a mile or so still counts for getting to one’s destination, the regenerative braking can still prove decisive.
One further benefit of the e-pedal and regenerative braking system in the Nissan Leaf is that it reduces some of the wear and tear that can happen on the conventional brakes. By not having to always apply the brake pedal oneself, you ensure that your brake pads, pedal and other connected components last longer.
However, no mechanical or digital system is ever perfect, and it seems that some drivers have experienced issues with the e-pedal and regenerative braking system.
What Are the Common Regen Braking Problems in a Nissan Leaf?
Sudden Failure to Activate
One of the most common complaints for Nissan Leaf cars from 2017 onwards has been that the regen braking would very suddenly but noticeably just not work on a random occasion when the driver removed their foot from the accelerator pedal. According to users reporting the problem on Reddit, it wouldn’t happen frequently, but it seems that even a 2-percent chance overall was enough to frighten some.
The trouble is that Nissan Leaf users get so used to the regenerative braking working all the time, that they can be slow to react if and when it doesn’t work, and that can obviously have serious safety implications. The cause of this issue was traced mostly to drivers noticing that it nearly always occurred when the car was being driven on rougher or more poorly paved roads. This could include country roads, badly maintained older roads, but also those undergoing resurfacing or other construction works. It also was seen to cut out when there was tire slippage on icy road surfaces.
Regen Brake Displays Not Showing Up
Another fairly common fault that was reported was another result of cold weather, even in the latest version of the Nissan Leaf. Namely, cold snaps causing problems in battery voltages meant that drivers were getting unreliable readings on the performance of their regenerative braking systems — among other things — with the screen not displaying much of the key information they needed.
While some assumed these problems were the cold interacting with the main lithium-ion battery pack, it’s actually the simpler — and mercifully cheaper to repair and replace — 12-volt battery system that is mostly at fault here. When users replaced their old 12-volt battery systems that were being killed off in sudden cold snaps (already years old), they found that these problems tended to fade away.
Faulty Regen Braking Functions Caused By Component Faults
At times, the physical components of the overall braking system might have faults that spill over and start to affect surrounding systems, including regen braking and one-pedal driving. For example, when was the last time that you had your ABS sensor/ring checked? A problem with this component can see other issues created, as can corrosion by the wiring contacts, or unwanted fluid pressure in the master cylinder, or a slightly warped brake rotor. These are the kinds of problems that are best avoided with regular and proper maintenance and servicing.
What Can Drivers Do About These Problems?
One of the first and most important things to remember is that your regenerative braking won’t kick in while your battery is fully charged. So if you’ve charged your Leaf to 100 percent in preparation for a longer journey, for example, you might notice that it doesn’t kick in until you lose a few percent at least from the capacity. Some people confuse this with there being a problem with the regen braking, because they recall that their regenerative braking and e-pedal has been set to active, but then it doesn’t appear to do anything. Don’t panic, it will kick in when the system detects that the vehicle needs energy to be reclaimed.
Some people buy Nissan Leaf cars and think that they’ll almost never need to take it into the shop. Here’s the thing – yes, electric cars need far less maintenance than regular internal combustion engine cars do, but that doesn’t mean they are maintenance free. Your wheels, brakes, lights, suspension and whatnot all need to be regularly serviced, as do the electrical components of your vehicle.
Keeping your Nissan Leaf serviced according to the OEM-recommended guide will ensure that it remains in optimum condition and that the chances of any surprise component failures are minimized.
Keep to well-maintained roads where possible, and avoid erratic, aggressive and otherwise uneven driving patterns. The Nissan Leaf wasn’t built for rugged adventure or for the racetrack. It’s meant to be a clean, eco-friendly way for people to take themselves from A to B. Treating the car as such will ensure that systems can work properly, and respond properly to your outside conditions.
Signs That Your Nissan Leaf Regen Braking Might Be Experiencing Problems
Always be on the lookout for signs that your e-pedal or regen braking system could be in need of professional attention:
- Spotty regenerative braking performance – cutting in and out randomly and frequently during any journey, long or short
- Spongy brake pedal or a brake pedal that shows little or no resistance when pressing down to the floor
- Brake system warning lights on your dash/infotainment display
- E-pedal and regenerative braking failing to bring the car to a full stop when set up to do just that