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

Hymotion: Handling Hills

Discussion in 'Prius PHEV Plug-In Modifications' started by Arthur, Oct 11, 2008.

  1. Arthur

    Arthur Member

    Joined:
    Oct 10, 2008
    94
    55
    2
    Location:
    Corning, NY
    Vehicle:
    2008 Prius
    I had my Hymotion system installed recently at Westboro Toyota, near Boston. So far, I'm getting about 80 mpg on mostly city driving.

    I live at the top of a very big hill. I've found that I get the best mileage if I leave the Hymotion system turned off until I get to the bottom of the hill. That way, I am still able to recover most of the braking energy on the way down the hill. If I start out with the Hymotion system on, it will "fill up" the Prius battery shortly after starting the car, leaving no room for capturing braking energy on the way down the hill.

    I've also found that I get about 20-25 miles of almost purely EV driving. I live about seven miles from town and usually make two round trips to town every day. I don't have quite enough battery power to make two round trips. So, I have to use a fair amount of gas on the return leg of the second trip. That's why I'm only averaging about 80 mpg.

    Even with my "turn on after going down the hill" trick, I suspect that I am using WAY more energy on the way up the hill than I can possibly recover on the way down. My total EV range would probably be greater if I didn't live at the top of a hill.

    One thing that I am very pleased about is my car's ability to go all the way up the hill in EV mode. Granted, I have to go fairly slowly (probably less than 20 mph) to keep the engine from kicking on. If I go too fast or hit a grade that is too steep, the car will kick out of EV mode and start the engine. However, all I have to do is back off the accelerator and the engine will go off.

    On the steepest grades, I have to avoid certain speeds. Right around 20 mph, the Hymotion system gets into a wrestling match with the Prius system. Hymotion keeps switching into EV mode (enging goes off) and Prius keeps switching back (engine comes on). So, I either go faster and let the engine stay on continuously or I go slower and let it stay in EV mode.

    Since I can't make two full round-trips on one battery charge, I am looking at ways to rearrange my schedule to allow an hour or two of charging time at home before making my second trip to town.

    I have also just ordered an engine-block heater, which I suspect will be very helpful in the coming cold months.

    Recently, I had a problem with my system and had to disconnect it from the car, but A123 Systems was very helpful. They actually ended up replacing my battery pack with a new one.

    Overall, my Hymotion experience has been very positive so far.

    Arthur
     
    #1 Arthur, Oct 11, 2008
  2. PeakOilGarage

    PeakOilGarage Nothing less than 99.9

    Joined:
    Oct 3, 2008
    334
    12
    3
    Location:
    Pacific Northwest
    Vehicle:
    2009 Prius
    I have had the same experience dealing with hills. I have about a 1/2 mile climb at a very steep grade. I can have a nice average MPG of 99.9 and then get murdered climbing that hill once or twice per day.

    I will try your advice of keeping the Hymotion off during downhill legs. That makes sense.

    I also can easily get 20 miles in pure EV mode around town. speeds under 35 mph are easy to maintain the EV mode of driving. Sometimes I can edge it up to 40mph all in EV mode.

    I am most amazed that I can even climb small hills in all EV mode with the Hymotion engaged. Steep hills are impossible, but it still works for gradual incline hills.

    An Engine Block Heater is a definite upgrade. Also a programmable timer to schedule your recharging (at night) and your pre-heating.
    I have also ordered the ScanGauge II trip computer and the Japan EV button kit. The EV button is not really necessary since it is easy to control the EV mode with only the gas pedal. But I want to see how they operate together.
     
    #2 PeakOilGarage, Oct 11, 2008
  3. gkalkas

    gkalkas New Member

    Joined:
    Sep 14, 2006
    58
    7
    0
    Location:
    Chicagoland
    Vehicle:
    2005 Prius
    Congrats! Mine is scheduled for early January. :)

    But i thought their EV mode only worked up to 34 mph, not 41, as the std Prius does? Can you tell me how that works? I thought that over 34, you would be in mixed mode?

    Thanks
     
    #3 gkalkas, Oct 11, 2008
  4. PeakOilGarage

    PeakOilGarage Nothing less than 99.9

    Joined:
    Oct 3, 2008
    334
    12
    3
    Location:
    Pacific Northwest
    Vehicle:
    2009 Prius
    I think I might be able to do it when using some slight declining grade hills. The glide effect kicks in and allows you to inch your speed up in all EV mode. In my region there are a lot of hills so it seems I am always climbing or gliding somewhere. Even when it appears flat, there is really some small percentage of grade to the road.

    So my numbers are always a bit extreme to either the low or high side, depending on the trip profile.

    I think the 34 mph limit is still in effect with Hymotion. I have noticed the gas engine kicking in automatically at that point. But it is easy to lift off slightly, enable EV mode again, then maintain speed around 33-35 mph.
     
    #4 PeakOilGarage, Oct 11, 2008
  5. gkalkas

    gkalkas New Member

    Joined:
    Sep 14, 2006
    58
    7
    0
    Location:
    Chicagoland
    Vehicle:
    2005 Prius
    Ok, I get it. It sounds like my EV button. It trys to stay in EV mode, engine kicks in at 34, but btw 34 and 41, can nudge it into ev mode... Sweet!

    Thanks,

    George

    PS Tesla??! :eek:
     
    #5 gkalkas, Oct 11, 2008
  6. PeakOilGarage

    PeakOilGarage Nothing less than 99.9

    Joined:
    Oct 3, 2008
    334
    12
    3
    Location:
    Pacific Northwest
    Vehicle:
    2009 Prius
    Oh yeah :car:
     
    #6 PeakOilGarage, Oct 11, 2008
  7. boxer93

    boxer93 Psyched for PHEV

    Joined:
    May 9, 2008
    155
    22
    0
    Location:
    Southern NH
    Vehicle:
    2008 Prius
    I think you'll find many times that the MFD will show battery power at all speeds. I don't have a lot of flat terrain. I can easily maintain this mode at 45, 50 even 70+. The newest screen that I'm now seeing is battery power and ICE power with the MPG at 99.9 I'm liking this more these days since I think it will keep the ICE warmer and be able to maintain the higher speeds with battery only.
    Also on Arthur's original point. I never shut of the Hymotion switch. I understand your wanting to save as much electricity. Another observation I have is that the L5 seems to have a constant supply of electricity to the car, almost irregardless of speed. I find that the L5 will run out of charge sometimes after 20Mi sometime 35Mi.
    Chris
     
    #7 boxer93, Oct 12, 2008
(You must log in or sign up to post here.)