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My mileage is improving

Discussion in 'Gen 2 Prius Fuel Economy' started by VABeachPrius, Jul 26, 2006.

  1. VABeachPrius

    VABeachPrius Member

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    Please forgive me if this was recently discussed or if everyone knows this already. I didn't put all the pieces together until recently. I still have much to learn.

    Hypothesis: I belive that one will get better mileage by keeping the SOC as high as possible on the HV battery using the pulse and glide technique using minimal stealth on roads with speed limits that are between 35-45 mph.

    Background: On roads with speed limits between 35-45 mph, after I have pulsed up to 40 mph (pending traffic situations) I glide down to about 30 or 35 mph (again traffic and traffic light dependent). I have noticed that during my pulses (on my car it will be slow/fast enough so that I see orange arrows from the engine to the motor/generator and wheels. There are no yellow arrows from the motor/generator to the wheels and there are yellow arrows chargine the battery while I pulse). Accelerating in this manner yields about 33-36 mpg, if I have a higher SOC of the HV battery. This is as best as I remember from the thread from the marathon prius drivers.

    If I use the battery too much trying to stealth (all yellow arrows), it affect my mpg during my next pulse acceleration. Observed assumption: The distance to accelerate from 30 to 40 mph is the same regardless of HV battery SOC; the mpg during the acceleration changes depending upon the HV battery SOC.

    With just a few bars of charge (after heavy stealthing) I only get about 15-20 mpg during my pulses (see assumption). At the same locations with a high SOC, my mpg during the pulses may be 33-38 mpg (see assumption).

    I have found it might be better to use pulse and glide with almost no stealth (unless the situiation calls for it and I have a high state of charge) in an effort to keep the SOC high such that during acceleration my mpg during acceleration is as high as possilbe as it means the glide distance requried for good gas mileage is greatly reduced. I recently went out and drove 26 miles on a 2ish mile loop near my house and averaged 92 mpg (MFD). I am at 606 miles at 66.8 mpg on the MFD.

    Have others found this to be true as well?

    Thanks for listening,

    Chris
     
    #1 VABeachPrius, Jul 26, 2006
  2. SomervillePrius

    SomervillePrius New Member

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    I try to use pulse and glide where possible and I've notices similar things as you.

    If I start out with a high SOC and use stealth (no arrows) to go from 40 -> 30 I will over time drain the SOC. When I then try to pulse up from 30 -> 40 the ICE will run harder (I get the same acceleration but the engine works harder). I take this to be the Prius trying to regain charge where it can (as it gets nothing and actually loose SOC during stealth).

    I've found that after a while the Prius don't want to stealth anymore and will run the ICE in almost any condition (even with decent SOC) for a few minutes. In times like this I resign to the Prius and Pulse slower letting the ICE stay on longer and more umph going to the battery.

    It's a complicated process, the dance we do with the Prius. I've found that stealthing until the battery drains too much reduces MPG.
     
    #2 SomervillePrius, Jul 26, 2006
  3. Ichabod

    Ichabod Artist In Residence

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    "No Arrows" = Glide
    Yellow only + ICE off = Stealth
    Pulse can be orange arrows and any combination of yellow arrows.

    I'm sure you're right about losing MPG by over-draining the battery, and that's exactly the reason I wouldn't consider an EV mod, no matter how cool it would be ;)
     
    #3 Ichabod, Jul 26, 2006
  4. SomervillePrius

    SomervillePrius New Member

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    Taking you definitions I agree.. Using stealth (i.e battery to propell the car) reduces overall MPG. This is a hybrid and not an EV. The battery should be mostly used in cojunction with the ICE or when the ICE is off simply to keep brakes, sterring etc.

    Stealth might be cool but not efficient for the Prius. I use it towards the end o fthe day if I know that I will get a new "warm up" cycle
     
    #4 SomervillePrius, Jul 26, 2006
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