Is using brake regen more efficient?

nicks-taycan

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It seems that having brake regen on (I tend to prefer it regardless) would offer better battery efficiency. Does it depend on driving style?

I’m curious because Normal driving mode doesn’t have it on by default. If I’m on a road trip trying to optimize for distance, better to have it on or off? Thanks!
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JimBob

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It's in some of the commentary from Porsche. Range mode is set up to prefer coasting. The issue might be when the regen occurs. If you apply the brakes you get regen. If you take your foot off the accelerator you may get regen. When driving for range, taking your foot off the accelerator you prefer coasting to regen.
 

JonasOfNorway

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I always use regen, why not?
Physics. Regen is not 100% efficient. There is a relatively high loss when converting the (potential) energy of the moving mass of the car to energy in the battery.

So when braking (with regen) and then later accelerating, you will have a substantial energy loss in each operation. And then it will be much more efficient to do nothing (coast).

This is a good read:
https://electrek.co/2018/04/24/regenerative-braking-how-it-works/
They say around 70% on regen.

But, having said that, how many percentages do you loose in the real world? No idea. Would be fun to see a test.
I see very little difference for example on range mode and normal mode (given same AC settings). And when taking in that the car will run of the front motor, and even dim the driving lights in range mode, the difference is not substantial in my findings.
 


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It's in some of the commentary from Porsche. Range mode is set up to prefer coasting. The issue might be when the regen occurs. If you apply the brakes you get regen. If you take your foot off the accelerator you may get regen. When driving for range, taking your foot off the accelerator you prefer coasting to regen.
in addition to braking to regen, when you coast, there is free coasting, regen off or there is coasting with a little bit of regen. watch the meter. I rarely use range mode, it retards some of the car's functions and offers minimal range gain.
 

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Physics. Regen is not 100% efficient.
with regen off there is zero regen, with it on there is some regen going on.
IMHO a little regen is better than no regen, regardless of the efficiency of the regen.
 

JonasOfNorway

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with regen off there is zero regen, with it on there is some regen going on.
IMHO a little regen is better than no regen, regardless of the efficiency of the regen.
Not totaly sure i understand what you are trying to communicate. But:

From a efficiency standpoint regen is super nice for stopping a car. The alternative is to use the brakes, they will just take your nice energy and give it away as heat to the atmosphere.

Again, from an efficiency standpoint, if your goal is to keep the car moving, and a braking operation is just temporarily, you are much more efficient with just coasting. (Compared to braking, accelerating, braking accel.)

In the good-to-know app you can read how porsche has enabled a coasting feature when the car is moving at highway speeds and certain parameters are met.
 


JimBob

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in addition to braking to regen, when you coast, there is free coasting, regen off or there is coasting with a little bit of regen. watch the meter. I rarely use range mode, it retards some of the car's functions and offers minimal range gain.
I tend to follow the manufacturers recommendations so use Range mode when travelling. As to the difference in Range vs Normal, that calls for a proper test.
 

kort

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Not totaly sure i understand what you are trying to communicate. But:

From a efficiency standpoint regen is super nice for stopping a car. The alternative is to use the brakes, they will just take your nice energy and give it away as heat to the atmosphere.
in the taycan regen is not strong enough to bring the car to a stop, or even slow it down significantly, the brakes must be applied. the braking system then applies more regen until more pressure is applied to the brake pedal to apply the brakes to bring the car to a stop. in other words there is no one pedal driving in a taycan.
I am curious, what method of bringing a car to a stop using brakes does not emit wasteful heating?
 

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I tend to follow the manufacturers recommendations so use Range mode when travelling. As to the difference in Range vs Normal, that calls for a proper test.
I am just going by the shown by the car when switching between modes. in my car the difference in range between range mode and normal mode is a mile or two
 

JonasOfNorway

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in the taycan regen is not strong enough to bring the car to a stop, or even slow it down significantly
I am gonna leave the discussion here, but for others that may find this thread and trying to find knowledge:

The gass pedal release regen is not as powerfull as for instance the teslas. But it will brake your car, and that has a theoretical impact on range. The mild regen will brake your car down to about 5-10 km/h before it needs brakes to come to a complete stop.
 

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This comment from Porsche “It is efficient to coast and keep kinetic energy in the vehicle.”

When you brake, you convert kinetic energy to electrical. There are times when this makes sense, for instance when you have to brake a lot. If you are just trying to drive a near constant speed, then coasting will be more efficient.
 

Gubbjaevel

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with regen off there is zero regen, with it on there is some regen going on.
IMHO a little regen is better than no regen, regardless of the efficiency of the regen.
Regen = braking car.
You need to use energy (> than the regen input) to get back to speed, as compared to just coasting.
That's why coasting is better than regen.

BUT

Efficiency would pretty much only come under scrutiny in range mode.
And in range mode, people would normally be on ACC/PID on a set speed.
Then it doesn't matter that much because ACC/PID dictates energy input/output. Not whether or not you have selected regen.

Real world difference, IMHO, will be very, very, very minimal.
It's more on the "feel" of the car.
 

Neptune

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There are two forms of brake regen, auto regen which happens when you let off the accelerator and regen that happens when you press the brake.

I feel that getting the max coasting distance is a better use of energy than trying to recapture it, because you recapture it when you brake anyways.
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