1. Attachments are working again! Check out this thread for more details and to report any other bugs.

coasting in neutral questions

Discussion in 'Prius c Fuel Economy' started by JupiterJ, Aug 12, 2013.

  1. drysider

    drysider Active Member

    Joined:
    Apr 14, 2008
    823
    332
    1
    Location:
    Liberty Lake WA
    Vehicle:
    2012 Prius
    Model:
    Four
    My driving is done mostly in areas with 35mph speed limits. Traffic is usually pretty light. I use the ScanGauge trip feature (AVG) regularly to assess various driving techniques. I am not familiar with BTA....I have the X-Gauge GenIII list but it is not on it, and I do not see it in the users manual. It looks like it is the same as AMP...battery amp charge/discharge. In most cases, I do not want AMP to be zero during the glide. The point is to use some battery energy to extend the glide and take advantage of the available efficiency. The discharge rate is usually below 10 amps, although it is sometimes better to increase the amp draw to avoid starting the engine, depending on road and traffic conditions. I never use the battery to accelerate from a stop. Recently, I have been using the minimum amount of accelerator pedal to push the power bar past midway and start the engine...keeping it just a hair above midway (if traffic allows). The slower acceleration seems to have a very positive effect on mileage, but I am still playing with it. Unfortunately, there are not any level stretches of road long enough to have a repeatable course for tracking mileage under various conditions.
     
  2. Agent J

    Agent J Hypoliterian

    Joined:
    Apr 27, 2010
    294
    111
    0
    Location:
    Sydney, Australia
    Vehicle:
    2007 Prius
    Model:
    N/A
    yup, AMP is the equivalent of BTA. in hypermiling, conservation of energy in whatever form is the secret. in the perfect world, you'd really want to keep amp draw to 0 while covering ground because it's the most efficent. however, this is impossible to pull off consistently so i go by the next least energy comsuming which is N.

    nothing wrong with using available battery power in accelerating as long as the car allows it with pedal play and not forcing it via EV.

    doesnt have to be a long stretch. u can still go in and out of N when u glide. see if u can improve mpg with this. : )
     
  3. drysider

    drysider Active Member

    Joined:
    Apr 14, 2008
    823
    332
    1
    Location:
    Liberty Lake WA
    Vehicle:
    2012 Prius
    Model:
    Four
    I was able to check the amp draw while driving in N this afternoon...I got the same 1.5a or as stated above. I can get the amp to zero pretty easily while in a glide. This would mean that you are wasting the 1.5 amps while in N since it is not being used to run the motor. My segment mileage was 88mpg (ScanGauge) and my current tank mileage (210 miles) is 67.5mpg. I will be above 70mpg before I need to fill up...unless something really odd happens. I used 10 amps or so from the battery while in glide, and when accelerating, I kept my I-mileage higher than my speed (which seems to be a good efficiency benchmark). I remember reading here in past years that keeping your I-mileage at half your speed while accelerating was good efficiency. I will try using N some more tomorrow.
     
  4. Agent J

    Agent J Hypoliterian

    Joined:
    Apr 27, 2010
    294
    111
    0
    Location:
    Sydney, Australia
    Vehicle:
    2007 Prius
    Model:
    N/A
    Great results man! Not sure about how the data is interpreted by the SG in the GenIII, but with the GenII, it's difficult to see consistent 0 amps when gliding. you're probably in ECO mode (?) where pedal sensitivity is less.

    If you can pull it off at the speed you want, then so much the better. I edited my post a bit and just changed 1.5 to 0.9 amps as the lower limit. That 0.9 - 1.5 amps is the normal parasitic load on the entire system when it is ON so even if you're stationary or moving, the system is drawing that amount of power unless it is regenerating at the same rate of discharge when gliding in D.

    Not really familiar with I-mileage indicator though. :)