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Why doesnt engine charge lithium battery while underway

Discussion in 'Newbie Forum' started by Chabelo, Jul 8, 2014.

  1. Chabelo

    Chabelo Junior Member

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    Perhaps i dont fundamentally understand this design. I drove my 2014 pip home from dealer, over 80 miles almost 2 hours. Anyway, when i got home i wanted to try EV mode but it said battery was too low.

    Are there 3 discrete batteries in pips? 12 v "traction" AND lithium? And the car cant charge the lithium pack?
     
  2. Easy Rider

    Easy Rider Active Member

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    Yes you clearly don't understand the workings of a hybrid.

    There are only two batteries: 12 V for computers and other "aux" devices and the HV lithium traction battery that helps power the car and runs the AC and charges the 12 V battery.

    While driving down the road, at a normal and reasonable speed, the lithium battery is slowly charged and discharged as conditions warrant.
    The battery is used for propulsion to keep the gas engine from working too hard, that is getting too far out of it's most efficient speed and load.
    Then when the load on the gas engine is light, or coasting down hill, or during initial braking, the traction battery is re-charged for when it will be needed again.

    IF you drive too fast......like maybe 75 MPH or more......the battery won't come into play hardly at all because the little gas engine is going full blast to propel the car and there isn't anything left over to charge the batttery.

    You apparently tried to force it into EV mode when it was already "low".

    And finally, to extend the life of the propulsion battery, it operates roughly between 20% and 80% capacity.
    It never is fully charged nor fully discharged.
    On the display, that means that there will always be one or two bars left at the top and bottom.

    AND......there are probably close to a hundred threads on here already discussing and describing all this in painful detail.
    Please do a little searching and reading.
     
  3. bisco

    bisco cookie crumbler

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    welcome to priuschat! you need to plug in your pip!:) then you will be able to drive in ev almost all you want. did you get an evse cable? the car can charge the lithium pack after it runs too low and won't allow ev, but you would have to be going down a reasonably long slope, normal driving won't generally recharge it enough to go back into ev mode. all the best!(y)
     
    #3 bisco, Jul 8, 2014
    Last edited: Jul 8, 2014
  4. GregP507

    GregP507 Senior Member

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    Yes, welcome to this forum, and I'll try to answer your questions as well. I bought my Prius 3 months ago, and I was also puzzled that I couldn't use EV mode, after driving it several hours. To do that, you need a surplus of power. In the case of a PiP, you get that mostly from plugging in.

    There is only one big hybrid battery, and a tiny 12V battery that is only for running the control system and accessories. The big battery is divided into 3 virtual partitions (not real partitions). I'll call them "top, middle and bottom" partitions. The bottom partition is always kept in reserve, because the rechargeable battery pack would be damaged if the voltage got too low. The middle partition accumulates and uses power from regeneration (coasting and braking) and also gets charged by the engine when absolutely necessary. The top partition is for the EV surplus, and shows up as "EV range." The top partition will not normally be charged by the engine. This is because it's very inefficient to burn fuel to charge the battery, then use that power to drive the wheels. The system tries to drive the wheels directly from the gas engine wherever possible, instead. If you start on the top of a large hill, the regeneration can actually charge the top partition, and you can have EV miles suddenly appear and continue to climb as you descend the hill.

    Hope that helps.
     
  5. fuzzy1

    fuzzy1 Senior Member

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    Charging it (top partition of the three 'virtual partitions' described by GregP) from the engine would defeat the entire purpose of a plug-in car. Plug-in cars want to get that propulsion energy from the electric grid, not from oil.
     
  6. GregP507

    GregP507 Senior Member

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    Exactly.