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charging prius battery pack?

Discussion in 'Gen 2 Prius Technical Discussion' started by omega II, Aug 1, 2008.

  1. omega II

    omega II New Member

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    hello,

    i am currently designing/building a phev and need to know some technical questions about charging the prius battery pack.

    1. toyota has set the battery pack to only get 80% charge and discharge down to 20% for extended battery life. how are they determining these settings? is it but the voltage?

    2. if so, does anyone know what the voltage setting would be on a charger for 80% charge with a 201.6 battery pack?

    regards

    david
     
  2. efusco

    efusco Moderator Emeritus
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    go to Calcars.org (or com?). Seriously, these guys can handle the PHEV conversion questions much better than we can (though there are a few that have done conversions here).

    Also, the low end of the SOC is closer to 35% and rarely goes below 40%. I've also seen the SOC as high as 84% in my Prius. I believe it is voltage that determines but I do not know the thresholds used.
     
  3. bwilson4web

    bwilson4web BMW i3 and Model 3

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    We don't know. NiMH battery characteristics are not strictly 'voltage' based. Worse, temperature shifts the curves as well as recent history. It is a hard problem and I would recommend reading the RC model literature to learn what little we know.
    It isn't so.

    Seriously, I would recommend getting something like an MRC 989 and a couple of experimental battery modules and then mapping out the performance. Then for fun, build your own charger and use the experimental modules as test articles. If done badly, you may get this result:
    [​IMG]
    NOTE: the charging current was reported to be modest, in the 1 A. range. The problem was charging without a safety shutoff system: (1) temperature, (2) dV detect, or (3) absolute voltage limit (risky because of the temperature and current dependency.)

    You are welcome to review my tests. But seriously, you need to read the technical literature, data sheets and do your own tests.

    GOOD LUCK!
    Bob Wilson
     
  4. Flying White Dutchman

    Flying White Dutchman Senior Member

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    above picture was becasue someone charged the battery with a to high amps for to long...
     
  5. [H]ackerK

    [H]ackerK Geek

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    Yicks!

    Now does anyone have the Toyota P/N for the batt charger or even docs or pics of it? I am interested to see it.... ;)
     
  6. ken1784

    ken1784 SuperMID designer

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    It is called "THS Charger".
    http://www.autoshop101.com/forms/Hybrid15.pdf

    Ken@Japan
     
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  7. [H]ackerK

    [H]ackerK Geek

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    Thanks Ken... It looks kinda complicated to make one, esp the 04 and later model seems like it need to speak to the battery ECU....

    Also it is true the THS charger only available as a "Japanese model" and there for the need for 120V -> 100V convertor?

    Another thing it just mention
    "This tool will charge the battery from below 15% SOC to 40-50% SOC in approximately three hours. Target SOC is 60%"

    Is that mean this THS charger is only design to bring the battery up to 60% (i.e. the 100% on the photo = 60% SOC)?

    Also it looks kinda complicated for a day to day hook up.... :glare:
     
  8. ken1784

    ken1784 SuperMID designer

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    - The current Prius is not designed for a PHEV.
    - The "THS Charger" is built for maintenance purpose only.
    - The charger is designed for the Japanese 100V area, you'll need 100V->110V step-up transformer in the US.
    - The charger is used to charge from approx 15% SOC (no engine starting capability) to 40-50% SOC (engine crankable).
    - The charger is not for the daily charging purpose.

    Ken@Japan
     
  9. omega II

    omega II New Member

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    Ken, my design consist of a Manzanita Micro PFC-30 Charger. This unit has the option of setting both the amperage and voltage. The prius battery pack will have additional temperature sensor. I need to know what will the maximum voltage setting be at 80% of full charge?
     
  10. ken1784

    ken1784 SuperMID designer

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    In NiMH battery chemistry, there is no such simple voltage vs SOC relations.
    The voltage value depends on a lot of factors, such as current, temperature, internal resistance, age, manufacturing lot and others.

    Ken@Japan
     
  11. omega II

    omega II New Member

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    Ken, will there be any problems having two power sources charging the prius battery pack at one time? meaning............ when the generator is charging during driving mode, another source of power is charging the same battery pack. my initial plan is to add a 12v battery pack 400Ahr, invert to the PFC-30, then charging the prius battery pack only when in driving mode, once the prius is turned off, charging will stop.
     
  12. Flying White Dutchman

    Flying White Dutchman Senior Member

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    not a smart thing to do
    you need contactors that stop charging the pack when you standing still
    or you will over charge the HV battery or overheat it.
    this can also happen when your gliding down a hill or when the pack just gets to hot from itself by using it a lot.
    and then the prius wil stop putting more energie in it but your pack wil still be doing that
     
  13. ken1784

    ken1784 SuperMID designer

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    If you're confident both charging systems know each other and contol the target SOC correctly, the answer is yes, otherwise no.

    Ken@Japan
     
  14. omega II

    omega II New Member

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    Would it work if a relay is connected to the existing battery pack cooling fan, when the cooling fan is activated, it shuts down the PFC-30, once the battery pack is cool to a specific temperature, the PFC-30 becomes activated?
     
  15. ken1784

    ken1784 SuperMID designer

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    No, because the PFC-30 has no capability to monitor and control the SOC.

    Ken@Japan
     
  16. Flying White Dutchman

    Flying White Dutchman Senior Member

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    i think omega wants to build a relay to switch the PFC-30 off when the cooling fans come on.
     
  17. statultra

    statultra uber-Senior Member

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    the charger i made uses a variac and produces between 100-200 volts DC, at very low amps, its basically a trickle charger.

    I only used it once in the situation where my 01 prius wouldnt start due to low SOC, i charged it in halves about 138 volts each and i was able to get it started afterwards.

    I think the problem is we need a smart charger, that will work with the HV battery ECU.

    Im sure that plugin prius concept from toyota has everything we need including the ECU's and this so called "smart charger"
     
  18. Flying White Dutchman

    Flying White Dutchman Senior Member

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    lets hope its going to hit the market soon
    and not with a big extra price
     
  19. omega II

    omega II New Member

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    F white D..........you are correct! A normally close relay will open when the fan is activated causing to stop the charge coming from the PFC-30. This may not be the total solution, but it will protect the battery pack from thermal overload.
     
  20. klodhopper

    klodhopper New Member

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    Actually, the NHW10 model had a built-in charging unit that ran off a 12V battery and was tied through the ECU. It managed to bring the battery pack to an acceptable SOC to start the vehicle. As the thread I linked to states, the unit was seldom used in Japan, so it was eliminated in the NHW11, and NHW20 models later sold in the USA.

    Boosting HV battery in NHW10 Prius - CleanMPG Forums


    Also Vicor makes a very versitile DC power supply, VI-FKE6-CUX, 110V AC in, and 300V DC out at 250W, which translates to about .87A at rated output. The pack can be charged in one piece, but needs monitoring for overcharging as well. Haven't figured out how to design a curved "trickle circuit" to tie into it as yet so that it wouldn't need the constant vigilance.
     

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