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Max regen capability

Discussion in 'Model S: Driving Dynamics' started by Lbyfz450, Aug 11, 2016.

  1. Lbyfz450

    Lbyfz450 Member

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    Ok so I'm curious what the maximum holdback/regen capability of the s/x are.. I don't currently own either ( reserved a 3) but just speaking curiously...
    Let's say a model x is towing its maximum load down the steepest highway around, would max regen slow it down/hold its speed, or does it not have that "hold back" capability..
    My dodge diesel pickups exhaust brake has about the equivalent of 130hp of braking power...
    Theoretically I would I assume it could produce as much braking power as forward power, but I don't imagine the battery could handle the 450-500KW of juice being slammed into it.
    Thanks!
     
  2. beingpaulp

    beingpaulp Member

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    On a Model S 85D the display has a max of 50kWh regen, it might be more, but thats all the display has. If you regen for a long time (i.e. going down a long hill) it will actually limit regen (and regen brakes) in favor of battery safety.

    The limit takes into account SOC (state of charge) meaning if you climb a steep hill and drain the battery to 10%, then go downhill, regen will work better than if you charge at the top of the hill to 90% and go down.
     
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  3. Lbyfz450

    Lbyfz450 Member

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    Ok good point! 50kw is only about 67 hp... That's not a ton of holdback, but plenty without towing I'm sure..
    Would be cool if they could use it to charge a supercapacitor or something where it could handle high peak amps
     
  4. David99

    David99 Active Member

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    Mine does about 60 kW max. The deceleration depends on speed of course. The faster you go the less these 60 kW slow the car down. Once the speed drops down below 50 mph, regen is gradually reduced and fades out at about 4 mph.

    As mentioned, a high state of charge limits regen a little. I have never went down a mountain where regen was reduced due to long times of driving with regen.

    There is no point or advantage in adding in a capacitor to take a high peak power from regen. It would just add more weight and complexity in the system without a real world gain.
     
  5. Lbyfz450

    Lbyfz450 Member

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    Race track/aggressive driving maybe?
    I'm sure the constant "in/out" of power creates a lot of heat, where just out may not be as bad.

    So even if you were at say 30% soc, 60kw would be the max you'd see likely?
    Wonder if the car is sensing it's slowing down so that's all it cares about, but if you had a heavy trailer on if it could provide more stopping power.
     
  6. MP3Mike

    MP3Mike Active Member

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    I don't think we have heard from anyone, but it is possible that the tow mode in the Model X might enable additional regen capabilities.
     
  7. David99

    David99 Active Member

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    My car definitely has a hard limit of 60 kW no matter how loaded it is, going downhill or not or what speed I'm going at (as long as it's over 50). Once speed drops below 50 regen is reduced as the speed goes down. It roughly keeps the deceleration constant and it does that by reducing regen as the speed gets lower. Someone did a test and it showed it's keeping it constant at 0.1 G (or was it 0.2?).
     
  8. James Anders

    James Anders Member

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    Somewhere in this country (and indeed the world) there's one road that's the highest, longest, steepest that would provide maximum regen for a max period of time.

    I wonder where this road is located? In this country and the world. I wonder if there's a regen record?
     
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  9. EVie'sDad

    EVie'sDad Member

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    I took a little trip from the Bay Area over to Las Vegas, and on the way back there was a 40 mile stretch where standard regen setting kept the battery (range) at the same limit over that entire distance, effectively not losing any range during that 40 miles. Now, if I could figure out how to go downhill both ways, then that would be very efficient.
     
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  10. Lbyfz450

    Lbyfz450 Member

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    Well that's good to know! i guess being ac it has to go through the inverter, so that's likely the limiting factor, since we know if it was dc the battery can handle 120kw+ no problem.
    Seems a shame to potentially have to use the friction brakes down a steep hill when you could recapture that though.
     
  11. jdw

    jdw Member

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    Couldn't find the post, but someone here drove down Mauna Kea on the big island of Hawaii - it's almost 14000 feet from the observatory to sea level and would have to be in contention for the record. I remember he posted a picture of his energy graph which was pretty amazing.
     
  12. EVie'sDad

    EVie'sDad Member

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    Standard Regen usually relieves the need to manually brake in most situations, until I need to come to a complete stop. Within a few months, you will have it down pat and will not need to jump on the brakes except for those rare unexpected circumstances we all run into.
     
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