[electric_eel]

For an ICE vehicle, it is a well know fact that coasting in neutral is not a great idea from the safety perspective. In an EV, setting the regenerative braking to 0 has a similar feel
to it (from the driving perspective). Particularly in descents it is advisable to use the regen braking and use the brakes to the minimum just like one would do with engine braking in an ICE car.

So my question is are you comfortable using regen 0 on highways. As such I have been very wary in using it even though I know for sure that regen 0 (unlike coasting in neutral) in sparse traffic often gives the best efficiency and comfort.

There is a notable difference between regen 0 and coasting in neutral. In an ICE vehicle accelerating out is impossible from the neutral (by definition) where as in an EV, press the throttle and your car accelerates. So the two are not the same.

MODS: you might want to move it to road safety if you think it is more relevant there.

[mally2]

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Thanks for the support & understanding

[electric_eel]

@ mally2

My question is not on the efficiency. I am more interested from the perspective of safety.
Let me rephrase. Is it advisable (from the safety issue) to use regen 0 ? The typical
argument given against coasting on neutral like in https://www.team-bhp.com/forum/techn...ml#post2390149 (Does coasting save fuel?) as far as I see is not applicable for the regen 0 situation.

(Except of course the hill descent case there one should select the appropriate regen level to avoid problems like brake overheating)

[mally2]

Originally Posted by electric_eel

My question is not on the efficiency. I am more interested from the perspective of safety.
Let me rephrase. Is it advisable (from the safety issue) to use regen 0 ? The typical
argument given against coasting on neutral like in https://www.team-bhp.com/forum/techn...ml#post2390149 (Does coasting save fuel?) as far as I see is not applicable for the regen 0 situation.

(Except of course the hill descent case there one should select the appropriate regen level to avoid problems like brake overheating)

There should be no safety issue as Regen 0 is a feature provided by he manufacturer

However for those who drive ice regularly getting accustomed to Regen 0 in highway can be a bit surprising

[VaibhavShatna95]

Regen 0 in EV is just too unnatural for me and keeps me hyperactive and on my toes while applying breaks.
I would rather use cruise control with Regen 1+ but to each his own I guess, you can adapt your driving style accordingly.

I have never tried coasting in neutral as well to be honest though.

[roy_libran]

Originally Posted by VaibhavShatna95

Regen 0 in EV is just too unnatural for me and keeps me hyperactive and on my toes while applying breaks.
I would rather use cruise control with Regen 1+ but to each his own I guess, you can adapt your driving style accordingly.

I have never tried coasting in neutral as well to be honest though.

Yes it does feel surreal!

On my Tiago EV though, on long straight expressways (e.g. YEW) where I can maintain a very constant speed (80-90 kmph), Regen 0 with Cruise Control gives me the best AEC figures than even Regen 1 with CC.

[mohanphadnis]

I use regen 0 all the time on highways, but this is way easier with kona/Ioniq 5/Ev6 because of the regen paddles, which means you can change the regen mode super quick and can go to highest regen level in a snap.
If I could not do this, I would stick to atleast some regen and won't let the car just roll down.

[tsk1979]

Originally Posted by mohanphadnis

I use regen 0 all the time on highways, but this is way easier with kona/Ioniq 5/Ev6 because of the regen paddles, which means you can change the regen mode super quick and can go to highest regen level in a snap.
If I could not do this, I would stick to atleast some regen and won't let the car just roll down.

A note of caution on regen with some Hyundai's. At max regen it often is like medium pressure brake. But the brake lights do not immediately light up. So its like hitting the brakes with medium pressure, with no indication to the vehicle behind you that you are braking.

I do not recall what particular regen setting has this issue, but be aware of this quirk.

[electric_eel]

Originally Posted by tsk1979

A note of caution on regen with some Hyundai's. At max regen it often is like medium pressure brake. But the brake lights do not immediately light up. So its like hitting the brakes with medium pressure, with no indication to the vehicle behind you that you are braking.

I do not recall what particular regen setting has this issue, but be aware of this quirk.

I think this was the situation with Ioniq 5's one pedal mode. I think Hyundai fixed this issue recently though

https://www.youtube.com/watch?v=U0YW7x9U5TQ

[electric_eel]

Originally Posted by VaibhavShatna95

Regen 0 in EV is just too unnatural for me and keeps me hyperactive and on my toes while applying breaks.
I would rather use cruise control with Regen 1+ but to each his own I guess, you can adapt your driving style accordingly.

I have never tried coasting in neutral as well to be honest though.

Good for you. One should never coast in neutral.

[jalsa777]

Firstly: Zero Regeneration is exactly equivalent Coasting in Neutral

However, it is 'safer' to use zero regen than to coast in neutral because of the difference between how the braking works in an EV vs ICE.

In an ICE car, it is not recommended to be in neutral on downhill sections because all the retardation load of the vehicle will be on the brakes, i.e. on the brake disks and pads. This can cause overheating of the brakes and thus reduce braking force which can be dangerous.

However, in an EV, when you depress the brake pedal, the regen is activated and increased depending on the brake pressure. This works in conjunction with the physical brakes. Even at very low brake pressures, when the physical brakes haven't even yet reached their 'bite' point, EVs experience retardation due to regenerative action. Thus retardation load on the brakes is much lower and thus risk of overheating is lower.

Thus, technically, you can use zero regen without much safety concern.

[lina]

I feel safer using the regen set to max level on my ZS EV. In an emergency situation, the car will start slowing down even before i press the brake. It also ensures that the brakes will last a long time. I rarely press the brakes for slowing down.

[mrgx9090]

Last weekend I was driving from Bengaluru to Chennai in my kona and I was using regen 0 and i felt it was useful when it come to mileage because when I started I had 99% charge with distance of 305 with AC on which means I was short of 35 plus kms to reach my home. However since I started exploring regen 0 option I was able use the free wheel motion in the undulate roads and bridges. I didn’t wait for charging. When I reached home I had 35 kms left range in my car. I felt to extend your mileage it’s good option to use in highways considering you drive very sensibly during free wheel. Because breaking is totally different during 0 regen usage.

[DarthVeda]

You get the same effect when driving with battery charged to 100%, in most of the cars, the regen won't kick in until you empty few % of charge. Level 3 or strongest regen will kick in once you have consumed say 8-10% of charge.

[electric_eel]

Originally Posted by DarthVeda

You get the same effect when driving with battery charged to 100%, in most of the cars, the regen won't kick in until you empty few % of charge. Level 3 or strongest regen will kick in once you have consumed say 8-10% of charge.

I have speculative theory here: Regen 0 due to 100% SoC is probably more dangerous than regen 0 due to switching regen off in a multi-level regen EV. My analysis is purely theoretical and more knowledgeable folks can refute or confirm this. If you are willing to experiment and report then even better.

I think there is a theoretical difference between no regen due to 100% charge vs no regen due to setting regen 0. (I say this theoretical because it needs to be verified for the car in question)

1. When the charge is 100 %, the car can only use the frictional component of brakes. Even for a light touch of the brake, one needs to engage the frictional brakes. (Reason given below so read on)

2. When regen is set to 0 for a car which is not fully charged (say 60% SoC), the brakes can use a combination of regen plus frictional brakes. After all the user pressed brake to slow down the car and it would be a waste to not use all the braking power at our disposal

Why can't I have regen at 100% SoC (as a safety feature) ?

The regen braking in car happens when the motor (which is run in generator mode during regeneration) is loading the charging circuit. This induces a back emf which adds the braking effect. Why does this happen ? There are multiple ways to think about it but here is one (crude) way , the current in the circuit (due to the load which in this case is the charging circuit) generates a magnetic field that acts in opposition to the magnetic field of the permanent magnet and this adds repulsion. Think of two magnets with their south poles facing each other approaching toward each other. The magnetic force repel and brings down their velocity.

When the car is 100% charged, the charging circuit cannot (rather will not be allowed by the BMS to) draw current from the generator. No current in the rotor coil means no back emf and no regen braking effect.

Is there some way to get regen braking (in addition to frictional braking) when SoC is 100% at least for emergency? Yes we can have a resistive load purely for this case. In this case there should be a way to get rid of the resultant heat. I am not sure whether actual EVs have these.

Can regen 0 be as bad as 100 % SoC ?

In a car which has multi-level regen, I am assuming even when the regen is disabled, explicit user brakes should activate the regen (assuming not fully charged). I do not see a reason why not to exploit this feature.

On the other hand if your car has a single regen on/off switch, it could very well be implemented by a single switch which connects or disconnects the regeneration circuitary. So setting regen to 0 disconnect the load to the generator and thereby disabling regen braking entirely (much like the 100% SoC situation).