[ZamboniMan]

I haven't seen a post that deals directly with this, so if I missed it, send me that link.

I know that even when you hit the brake pedal, it starts with regen and then switches to the brakes if the pedal is pushed far enough. Which begs the question: How low can you go? I've tried to feel when the actual brakes kick in, but haven't been able to detect it. Is there any way to know when I'm reaching the max regen capability? I want to recoup as much energy as I can.

Thanks!

 

[srmarti]

Regeneration actually starts when you back off the accelerator. As the regen and brakes are blended I don't think it's easy (maybe impossible) to feel when the friction brakes engage. Best technique I think would be to avoid hard braking. Someone can chime in with max regen rate? Think it's somewhere around 50 kw for Gen 1.

Might want to try using L and modulating with the accelerator and see if you like driving that way. Maximizing regeneration isn't necessarily the most efficient thing to do. Others claim they do better coasting.

 

[caronjeff]

Coast and regen all you want, but remember to occasionally get hard on those brakes in order to keep them clean and functional. Forum members in high winter salt areas have experienced rusted, corroded rotors, especially the rears, from lack of use.

 

[ZamboniMan]

Might want to try using L and modulating with the accelerator and see if you like driving that way. Maximizing regeneration isn't necessarily the most efficient thing to do. Others claim they do better coasting.

Yeah, I feel like coasting gives me better range than using L. My traffic is light enough that I have more go than stop. I do sometimes switch to L when I see the light change in the distance, but am worried about the additional wear from the frequent shifting.

 

[Barry]

Not sure if this is different on the 2014, but on the 2013, you can set the DIC to display the power meter. That shows how many kWh of regen you are getting, and it shows when it maxes out.

 

[ZamboniMan]

Not sure if this is different on the 2014, but on the 2013, you can set the DIC to display the power meter. That shows how many kWh of regen you are getting, and it shows when it maxes out.

I do usually watch the power meter, but I am trying to figure out when the brakes kick in, so I can "brake" just to that point to get the most out of me slowing.

 

[obermd]

In the Gen 2 Volt, the power meter turns yellow during hard braking. I suspect that's where the brakes actually start to engage and the regen is maxed out. I don't know if the Gen 1 does the green to yellow change.

 

[freshcut]

I personally have never felt the friction brakes engage by feel. I've manually done it by shifting to neutral and didn't really notice a difference from the feeling I get through regenerative braking. I've also used the mygreenvolt app and had the checkbox for the app to alert when friction brakes are engaged and didn't notice anything that clued me into the fact I was blending. It just felt like I was braking as normal.

So back to your original question, aside from a lack of visual cues that your DIC provides for friction braking, you can always use the mygreenvolt app with "friction brake in use" sound and an OBD2 dongle.

 

[wordptom]

The My Green Volt app can be configured to produce a sound whenever the friction brakes are engaged.

Don’t forget, you get regen in both D and L.

Think of it this way. When your foot is on the accelerator, electrical energy is used to turn the motor’s shaft, which then turns the wheels to move the car down the road. When you take your foot off the accelerator, the car’s kinetic energy keeps the car moving. The turning wheels now turn the motor’s shaft, transforming it into a generator, and creating electricity (regen), even in D.

Adjusting the generator’s circuits adjusts the generator output. Increasing generator output requires applying more torque to the generator shaft. Applying more torque consumes the car’s available kinetic energy faster, i.e., coasting in L slows the car down faster than coasting in D.

The quantity of regen is affected by amount of time spent in a particular slowing down mode (i.e., D, L, paddle, or modulated brake pedal). We normally do not "coast" (slowing down without friction brake use) all the way from a moderate or high speed to a stop, and if we did, it should turn out that, but for friction losses, etc., the longer time coasting in D produces nearly the same amount of regen as the shorter time coasting in L.

In normal urban traffic, then, when you see a traffic light in the distance turning red, do you get more regen by coasting in D for a number of moments, or by keeping the foot on the accelerator until you’re closer to the light and then coasting in L for only a short moment, or somewhere in between by using the brake pedal to modulate the regen level?

Note that if it more time passes when coasting in D than when coasting in L to reach the spot where the car in front of you is stopped for the traffic light so you must stop, too, it also increases the chances the traffic light will turn green before you get there, reducing the amount of battery energy needed to get the car back up to traveling speed. Modifying your driving habits just to get more "last moment" regen might not have any impact on the overall regen quantity created in the car’s lifetime.

 

[llninja]

I haven't seen a post that deals directly with this, so if I missed it, send me that link.

I know that even when you hit the brake pedal, it starts with regen and then switches to the brakes if the pedal is pushed far enough. Which begs the question: How low can you go? I've tried to feel when the actual brakes kick in, but haven't been able to detect it. Is there any way to know when I'm reaching the max regen capability? I want to recoup as much energy as I can.

Thanks!

You are looking at this all wrong. You do not want to maximize regen, you want to minimize it, and maximize your momentum. So if you are in L trying to use regen paddles to maximize regen, you will find yourself staying on the accelerator longer until the best possible moment to pull max regen. Staying on the accelerator uses more energy, and regen is not 100% efficient - approximately 70% of your momentum is converted to battery, so yor'e burign 30% or so. Meanwhile your passengers are getting motion sickness. But if you were to drive in Normal D, and as you are approaching a stoplight with a red light, lift the accelerator very early, coast as long as possible, and quite possibly not even need to use the brakes, or if you do, hope that the line of stopped cars begin to move before you have to brake further. Over the long haul, you will see higher guessometer results minimizing regen rather than maximizing it in most conditions. The only condition where you do want to maximize regen is if you have an empty battery and you are going down a steep hill. Even then using the brake pedal should be just as effective as being in L and pulling the regen paddle. I contend the brake pedal gives you variable regen where the paddle and L only give you 2 fixed regen capabilities

As for when the brakes kick in, there are 3 scenarios:

1. Panic stop where you slam on the brakes
2. Any braking when in N
3. At about 5 mph down to 0 mph in a normal stop... in other words very little brake wear.

After nearly 80k miles of only using the brake pedal and very rarely driving in L (and never using the regen paddle, because I don't have one - gen 1) my brake pads barely look worn at all.

So for efficiency, safety, and no worries about wearing out the brakes, just drive and stop trying to maximize regen.

Edit: aw man, wordptom pretty much said the same thing that I did (we were both typing at the same time, and I got beaten to the punchline by 3 minutes).

 

[TSquare]

I haven't seen a post that deals directly with this, so if I missed it, send me that link.

I know that even when you hit the brake pedal, it starts with regen and then switches to the brakes if the pedal is pushed far enough. Which begs the question: How low can you go? I've tried to feel when the actual brakes kick in, but haven't been able to detect it. Is there any way to know when I'm reaching the max regen capability? I want to recoup as much energy as I can.

Thanks!

Don't worry about recouping energy. Just concentrate on coming to a smooth, gentle stop. The car does all the worrying for you.

 

[ZamboniMan]

Thanks, LLninja and wordptom! I probably didn't word my query properly, but your answers gave me the info I was looking for!

 

[bykerbyrd]

In every one of our 5 Prii that my wife and I have owned, as well as in our 2012 Volt, I'm pretty sure that I've felt the "modulation" or transition from regen to friction braking at around 5 to 7 mph. You can feel this by stopping slowly while in Drive with the foot lightly touching the brake, carefully holding it in the same position as the car slows, and watching the speedometer. You should feel an oh-so-subtle change in the pedal at the 5-7 mph mark.

I haven't seen a post that deals directly with this, so if I missed it, send me that link.

I know that even when you hit the brake pedal, it starts with regen and then switches to the brakes if the pedal is pushed far enough. Which begs the question: How low can you go? I've tried to feel when the actual brakes kick in, but haven't been able to detect it. Is there any way to know when I'm reaching the max regen capability? I want to recoup as much energy as I can.

Thanks!

 

[srmarti]

In the Gen 2 Volt, the power meter turns yellow during hard braking. I suspect that's where the brakes actually start to engage and the regen is maxed out. I don't know if the Gen 1 does the green to yellow change.

I does. but I think that's just an efficiency warning and not necessarily friction brakes engaging. It also turn yellow if you mash the throttle...

 

[srmarti]

In every one of our 5 Prii that my wife and I have owned, as well as in our 2012 Volt, I'm pretty sure that I've felt the "modulation" or transition from regen to friction braking at around 5 to 7 mph. You can feel this by stopping slowly while in Drive with the foot lightly touching the brake, carefully holding it in the same position as the car slows, and watching the speedometer. You should feel an oh....

I don't feel it on my Volt and I still get a regen indication at 3-4 mph in L.

 

[bykerbyrd]

Try it in Drive. Putting it in Low is like stepping on the brake 3/4 of the way down or so.

 

[ZamboniMan]

Thanks, bykerbyrd. I'll try that this evening! All in the pursuit of longer range!

 

[caskConditionedAle]

I would rather not "play games" when it comes time for braking. Brake as hard as the situation warrants. If you'd like to avoid using the friction brakes, drive in such a manner where hard braking is rarely needed.

1. Leave extra room between yourself and the vehicle in front of you.
2. Anticipate slowing down instead of waiting for the last minute.

 

[ZamboniMan]

I would rather not "play games" when it comes time for braking. Brake as hard as the situation warrants. If you'd like to avoid using the friction brakes, drive in such a manner where hard braking is rarely needed.

1. Leave extra room between yourself and the vehicle in front of you.
2. Anticipate slowing down instead of waiting for the last minute.

Thanks. That's what I'm doing. I just want to get the most "Go" from my charge.

 

[llninja]

Thanks. That's what I'm doing. I just want to get the most "Go" from my charge.

And realize that the most go from your charge would mean lowering your overall speed and avoiding any stopping. Ari_C accompanied 81.8 miles of EV range driving his gen 1 volt (with the smaller 35 mile battery) by burping the battery, using pump and glide, and driving around in a large rectangle at FedEx Field (Washington Redskins parking lot) for 4+ hours.

For me, I just put it in drive and take on any and all pony cars and ricer boys at stoplights. I'm still getting over 70 MPG on my 50 mile commute, which blows away any Prius, so I'm not worried about hypermiling any more. Live a little, just let the car do what it does.