What do the markings on the power/charge meter mean for charge?

Discussion in 'Clarity' started by MNSteve, Dec 4, 2018.

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  1. MNSteve

    MNSteve Well-Known Member

    Screen Shot 2018-12-04 at 3.37.58 PM.png
    This is an illustration from page 122 of the Owner's Manual. My question relates to the part of the arc labeled "Charge". This is obviously a measure of the regenerative braking capturing power and sending it back to the battery. The first part of this area is indented, then there is a tick-mark on the left and the indented area ends, then another tick-mark. Does anyone know the significance of these markings?
     
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  3. Viking79

    Viking79 Well-Known Member

    The tick marks represent some arbitrary power level, I don't think anyone has figured out exactly how much or if they are linear. The wider arc is probably just a style feature.

    So if the battery is not all the way charged and you brake while driving at speed you will see the regen max out. My hunch this is around 50 kW of power briefly, but just making educated guess.

    On the power side the scale is different and spread out over the range to make it more speedo like.
     
    Last edited: Dec 4, 2018
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  4. KentuckyKen

    KentuckyKen Well-Known Member

    I don’t think they have any intrinsic qualitative meaning. I just consider them to be place markers to show how fast I’m accelerating or draining the battery. In normal traffic in town, I never go past 12:00 in Econ and I can easily keep up with most traffic from a red light stop. I can’t say that they do much for me except maybe to keep me from lead footing it as much.
     
  5. MNSteve

    MNSteve Well-Known Member

    I understand the positive power-used part of the meter, although I agree that there's probably no intrinsic qualitative meaning, other than if you go past the "detent" the engine will start.

    It's the bottom part that makes me curious. It would be nice if it indicated when it transitions from regenerative to traditional braking. Not that it would change anything . . . if you're braking that hard, there's a reason.
     
  6. Ray B

    Ray B Active Member

    I agree with KentuckyKen that it probably has no absolute meaning, but - just thinking out loud here - I wonder if it may be somewhat bad for the battery to go past that first tick mark on the Charge side. Part of my commute has a long downhill off-ramp and it usually results in about 1 - 1.2 miles of added range after about 30 seconds of deceleration (just a guess) which is hovering around that first tick mark IIRC. That's about 120 mph of recharge power (approaching Tesla supercharger rate?), which is ok for occasional short recharge stints like mine, but probably not healthy for long term battery life to routinely recharge that aggressively.

    All speculation on my part ...
     
    Last edited: Dec 4, 2018
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  8. KentuckyKen

    KentuckyKen Well-Known Member

    I use the bottom, green, regen part to tell me when I’ve maxed out the regen and am into the friction brakes. As I understand it, as long as you don’t bottom it out, you’re regening and not using any more friction brakes than using the paddles. You’re just able to get more regen braking than paddles alone.
    I attribute my better than average range and MPGe to “coasting” up to stops in regen 1 and not pedal braking so hard that I bottom out the regen and call for friction brakes. I think that it is all or almost all regen until the very last few mph to a full stop. Another plus of this strategy is that I am not getting the ICE start up at full charge/limited regen that I got twice when I had to brake hard to avoid someone who pulled out in front of me right after leaving home.
     
  9. insightman

    insightman Well-Known Member

    How did you come by this understanding? It would be great if there was an OBD-II signal that shows when the calipers are activated, then we (or at least AnthonyW) could validate this understanding. Either that or wait years for when the brake pads wear out and start making noise.
     
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  10. KentuckyKen

    KentuckyKen Well-Known Member

    I assume (and you know the old saw about when you assume you make an a** out of u and me) that as long as harder pedal effort increases the regen, then it’s choosing regen over friction and I haven’t reached the point where I’m calling for so much deceleration that it needs the friction brakes. But you are correct that I have no hard evidence on this. Based on this assumption, then if I bottom (or max) out the green regen, then it must then go to predominantly friction braking. But then I’m assuming (again without hard proof) that before then it’s greatly favoring regen over friction braking. It just seems logical that it is doing this.
    I too would very much like more information. What I really want would be an indicator you could call up that would show the ratio of regen to friction braking. Maybe a simple meter like an efficiency indicator in reverse; swings into red zone as friction brakes activate and staying the green is regen braking. Or even just a red idiot light that comes on when you go under 90% regen and deactivates under 5 mph. Then you could coach yourself into high efficiency driving/braking.
     
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  11. Bina12834

    Bina12834 Member

    I don't know what the "tick" marks are but I use them to help me make sure my foot isn't getting too heavy on the go pedal. Around town I usually try to keep acceleration below the 10 o'clock tick (1st longer tick on the Power side).
     
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  13. MNSteve

    MNSteve Well-Known Member

    I want to explore something related to regenerative braking. I think I understand this, but let me pose it this way . . .

    I'm tooling along [that's a technical term] and see a light change quite a ways [another technical term] in front of me. Assuming that I don't stomp on the brakes hard enough to engage any friction braking, and ignoring any small effects of higher voltage loss at higher currents or battery not accepting the incoming charge as well, my understanding is that the net effect of these ways of coming to a stop are identical in terms of capturing the energy back into the battery:
    • Lifting my foot off the accelerator and letting the default braking slow me until I get close enough to the light to apply brakes to come to a stop.
    • Light pressure on the brake so that I slow down through the entire distance, coming to a stop at the same place but not changing pressure on the brake.
    • Using the paddle to set the braking to accomplish the same thing as the previous bullet.
    • Adjusting the pressure on the accelerator so that the power meter reads zero, then applying brakes fairly close to the stop. Remember my assumption that I didn't brake hard enough to invoke friction braking.
    It's my assertion that all of these capture the same energy from regenerative braking, just in slightly different ways.
     
  14. Bina12834

    Bina12834 Member

    Since unfortunately we can't do "1 pedal driving" in the Clarity I use the regen as much as I can when coming to a stop. It may accomplish the same amount of regen as just using the breaks, but I figure at the very least I'm saving some wear on the break pads.
     
  15. MNSteve

    MNSteve Well-Known Member

    This is exactly what I am trying to understand. No, I don't think you're saving anything. Unless you brake heavily, the brakes will not invoke the pads. The effect of light brake pressure and the effect of using the paddles is exactly the same.
     
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  16. Bina12834

    Bina12834 Member

    So what you're saying is that cranking up the regen to 4 chevrons (by using the steering wheel - pedal) to slow the car down to almost a complete stop and using the foot break pedal to complete the stop will amount to the same break pad wear as only using the foot break pedal to come to complete stop?
     
  17. So far, I’m enjoying the extra involvement the paddles allow.

    I’ve been gradually increasing regen, trying to time it so brake is only needed at the very end. That, combined with brake hold, has been a pleasant diversion. It may lose its novelty after a while, but for now it’s fun.
     
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  18. Richard_arch74

    Richard_arch74 Active Member

    Here is how I look at the regen v braking: 4 chevrons = no break pads regen (which is maximum regen without using break pads). When you are coming to a stop using maximum paddle regen and you find that you need additional help to stop (even a little) you are then applying the break pads. Also, as a side note, has it been determined that break lights come on at a certain amount of regen (1 v 2 v 3 v 4 chevrons)?

    Sent from my SM-G955U using Inside EVs mobile app
     
  19. Bina12834

    Bina12834 Member

    I understand that we cannot come to a complete stop only using regen (ie. 1 foot driving as it is know in the EV community). What I'm saying is that using the regen breaking to help slow the car down to an almost complete stop, then using the foot break to finish the stop logically has to be easier on the break pads (thus less wear) than solely using the foot breaks to bring the car to a complete stop.
     
  20. MNSteve

    MNSteve Well-Known Member

    Yes.

    If you extend the stopping interval sufficiently so that you do not need to dip into the range where you invoke friction braking, it does not matter if you use the paddles or the pedal. Since you cannot invoke friction braking using the paddles, you can be absolutely sure that you're not wearing out your brake pads. But if you're gentle on the pedal, you won't hit that range either. There seems to be consensus that as long as you don't pin the needle on the bottom (where it says "charge") that you're not using friction brakes. In normal driving, that should be easy.
     
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  21. MNSteve

    MNSteve Well-Known Member

    And what I am saying is that you are NOT invoking friction braking by pressing the brake pedal under normal driving conditions. Sure, if you have to stop quickly, you need traditional friction brakes, but that's rather beside the point since you're not going to be able to stop quickly using the paddles. If I have 100 feet to stop for the light that just turned red, it makes no difference if I use the paddles or light pressure on the brake pedal. In neither case am I using the friction brakes during the deceleration.
     
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  22. Richard_arch74

    Richard_arch74 Active Member

    I am agreeing with you, that it should be easier on the break pads. I'm just questioning some of the other posters when they theorize that light pressure on the breaks is not initiating the break pads but is giving us more regen than the paddles can give us. I'm saying that once you apply maximum regen through the paddles, if you need more deceleration, you are using the break pads.

    Sent from my SM-G955U using Inside EVs mobile app
     
  23. Bina12834

    Bina12834 Member

    So light to moderate pressure on the foot brake (the regular brakes) still does not press the brake pad to the rotor but rather invokes the regen braking? Only heavy foot braking will cause the ‘regular’ brakes to engage?
     

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