Regen or Coasting — Which is better for your EV?
Somebody once described regenerative braking to be a bit like engine braking, where you use the car’s gears to help slow the vehicle. That’s if you don’t mind a loud sound of your pistons working overtime. Thankfully, electric driving is a little smoother and offers its regenerative powers without any glancing looks of concern from your passengers.
Regenerative or recuperative braking is a result of electromagnetic resistance inside the electric motor when the flow of electricity is stopped. This kinetic energy is dynamo-generated and converted back into the battery as chemical energy, ready to be used again.
Some EVs have a standard, strong regen, while other manufacturers offer adjustable controls at varying degrees down to turning the regen entirely off. Which most people, new to EVs, prefer.
I started driving EV’s in 2013 in a BMW i3. This EV has quite strong regen which cannot be toggled off. It was unlike any driving style I had experienced before, but it didn’t take me more than a few days to get used to it before I began using the accelerator to gradate the power up to the wheels. Over time my driving style changed to what is now known as one-pedal driving.
This term meant that you rarely had to use the footbrake for most of your driving so long as you used reasonable traffic anticipation. The car comes to a complete stop and holds still on a hill or level road. Other EVs which also have strong regen work a little differently — they will bring you down to 5mph when the regen switches off and you apply the foot brake at the end. (This is because it takes a bit of battery energy to bring the car to a complete stop).
But which method is best — regen or coasting?
It all depends on user preference. Having spoken to many EV drivers in my time on social media and watching online reviews, I know most of us prefer to have the option of adjusting the regen strength. It’s more engaging for the driver to toggle between the modes depending on terrain, traffic conditions or to gain a bit more battery range on a long, steep downhill drive or coming off the motorway onto a slip road.
Let’s have a brief look at the pros and cons:
The problems with regen braking:
- Motorway driving — some drivers are concerned about how their brake lights communicate with drivers behind.
- The immediate feeling of braking when lifting off the accelerator can feel unpleasant if you forget to lift up gently (easing off the power).
- No apparent ability to coast (not talking about a neutral gear)
The benefits of regen:
- It converts the car’s kinetic energy back into your battery as chemical energy making your EV more efficient.
- Brake pads and discs last longer.
- Braking distance is reduced in the time between lifting off the accelerator and applying the footbrake. Every metre counts, especially at higher speeds.
- It helps to prevent over-driving your car caused by frequent braking and accelerating. You can find an analogue position on the accelerator to hold your speed, even on a downhill.
Is Coasting more efficient than regen?
If you can keep moving forwards without using power, then coasting is better, but regen should be used when you NEED to brake. This combination will give you the best efficiency per mile. But you’re going to have to toggle this yourself. You either turn off regen (or set it to minimum) for motorway driving and toggle regen to maximum when you’re in traffic, frequently stopping and starting. This takes us back to the one-pedal driving style I alluded to earlier. It puts less strain on your car’s brakes and your foot switching between pedals. You won’t pollute the streets with so much brake dust and your brakes pads will last thousands of miles more, because the regen uses electromagnetic resistance in the motor instead of the brake pads.
I think it boils down to personal choice. What do you prefer? The adjustment on most new EVs is now there to use, and if you toggle it correctly, you’ll add to your overall driving efficiency (measured in miles or km/kWh).
If your EV doesn’t have adjustable regen strengths, you can still coast by holding the power level between accelerating and regen. Most EVs, like the i3, have a power indicator near the digital speed display.
In conclusion, if you’re new to EV’s you might prefer to have regen switched to low or off, but you should consider getting some of that forward energy back into your battery, rather than wasting it as heat on the brake discs.
Horses for courses, I know! But it’s worth considering making your range last and seeing a better efficiency score in your EV display. Think of mi/kWh as your new MPG and enjoy one amazing aspect of EVs — their very cheap running costs.
