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HV battery charge bars, low mpg

Discussion in 'Gen 4 Prius Fuel Economy' started by amos, Aug 7, 2023.

  1. amos

    amos Active Member

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    hello all
    in past 3 months i have noticed a down to 40 city/45 freeway. i did some maintenace like spark plugs change, air filter, battery filter, coolant replace and more minor like air pressure, with very conservative driving, mpg came up to about 50 mpg.
    yet i have noticed a full tank gets about 500 miles and it seemed like to get this 570 miles, the car has to do 58 mpg but all i got was max 47 mpg.
    now in past month, i noticed most of the time i only have 2 bars and sometimes 3. last time i went to a car wash tunnel, was in neutral ( no charge phase). charge was down to only 1 bar and flashing warning display came up asking me to put the car on D immediately.i pulled out of the tunnel with almost no battery.
    if i drove down hill for about 4 miles than i would get full bars, which than goes down to 2 bars. where that ride was supposed to give about 60 even 70 mpg ,i got 45 mpg.
    my average city mpg now is 35-40.
    i checked and no DTC , 0 dtc recorded. past DTC history shows :
    c1300 - skid control ecu
    c1241 - low or high power supply voltage, c1242 open circuit in ig1/ig2. power source circuit.
    this was past dtc's recorded. is it relevant?
    is the battery dying or else maybe just a cell? car has 147k miles on it now.
     
    #1 amos, Aug 7, 2023
  2. bisco

    bisco cookie crumbler

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    It sounds like a weak battery, but not bad enough to throw a code.
    Maybe consider a grid charger
     
    #2 bisco, Aug 7, 2023
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  3. amos

    amos Active Member

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    whats a grid charger exactly? my car is not prime, do youmean charge the battery over the 110v grid at my home? directly to the battery?
     
    #3 amos, Aug 7, 2023
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  4. bisco

    bisco cookie crumbler

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    look up hybrid automotives prolong charger. it is a charger for the hybrid battery that charges and discharges it to extend the life.
    'grid' because you plug it in? not sure to tell you the truth.

    what-s-a-grid-charger
     
    #4 bisco, Aug 7, 2023
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  5. amos

    amos Active Member

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    not a bad idea, might try it. though seems like some cells are getting weaker.
     
    #5 amos, Aug 7, 2023
  6. FuelMiser

    FuelMiser Senior Member

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    I'm guessing your Gen 4 has the NiMH traction battery, and it is simply approaching end-of-life at 7 years and 147K miles. Nothing unusual for this style of battery. Best to find a shop that refurbishes Prius NiMH batteries. They will exchange your battery for one that is refurbished with new cells and load balanced. It should not be hard to find such a shop since all Prius came with NiMH batteries prior to Gen 4, when some models came with Li-Ion. Perhaps look at the Gen 3 and Gen 2 sections for discussions of battery replacement in these models.
     
    #6 FuelMiser, Aug 8, 2023
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  7. vvillovv

    vvillovv Senior Member

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    What scan tool did you use to get the codes? what version is the software?
    The only way to know for sure - - or at least get a clue of what is or went wrong with the car is to hook the car up to techstream.

    Here are 3 links to give a general idea about what the 3 codes you listed mean

    https://www.dtcdecode.com/Toyota/C1300

    https://www.dtcdecode.com/Toyota/C1241-41

    https://www.dtcdecode.com/Toyota/C1242-42
     
    #7 vvillovv, Aug 8, 2023
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  8. amos

    amos Active Member

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    just used a basic scanner made by innova 5110. im also guessing that the old dtc i had c1241 is regards the 12v battery. i had an issue with that about a year ago. anyways it was only registered in code history
    i have no CEL now. and the DTC is 0. i am considering a battery rehab but first i need to check each individual cell for voltage. i think its supposed to be around 16v.
     
    #8 amos, Aug 9, 2023
    Last edited: Aug 9, 2023
  9. amos

    amos Active Member

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    yes with 2016 type ii model they still have nickel type battery. though its still under warranty, dealer said need to see code P0A80 before authorizing warranty replacement.
     
    #9 amos, Aug 9, 2023
  10. vvillovv

    vvillovv Senior Member

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    Why not try out DrPrius ? It might give you a better idea of what and exactly where many of the cars battery issues come from.
     
    #10 vvillovv, Aug 11, 2023
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  11. FuelMiser

    FuelMiser Senior Member

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    I didn't mean to suggest you could get a warranty replacement. Maybe my phrase "approaching end-of-life" was misleading. It hasn't failed. It's just not as efficient as it once was. You'll get lower MPG but it will still run without errors.

    We continued to drive our 2005 even though the state-of-charge (SOC) meter would swing rapidly from FULL (green bars) to EMPTY (purple bars, I think) when driving downhill or uphill only a couple of miles. After coasting downhill and filling up, we had to use B mode to save the friction brakes to assist in braking after no more regen could go into the battery.
     
    #11 FuelMiser, Aug 11, 2023
  12. amos

    amos Active Member

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    i was reading about battery recomdition. seems like an easy task but will take about 48 hrs and need to remove the battery out. i will try to find a low cost place for that or do it myself. any recomendations will be appreciated. all thats needed is about 2-3 cycles of charging and discharging the battery untill all cells will equalize the charging level. i dont believe that p0a80 will come soon. i drove this wekend about 200 miles l.a to santa barbara at about 65 mph and got 46 mpg. so maybe i will try that cell balancing process next weekend
     
    #12 amos, Aug 14, 2023
  13. amos

    amos Active Member

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    i have all that OBD and a very expensive scanner (it cost about $15k ) but its not with me. im planing to spend more time to figure it out next weekend
     
    #13 amos, Aug 14, 2023
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  14. amos

    amos Active Member

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    i had that situation as you describe when no more gen into battery. so in that situation, if on freeway and no car near me ( 6% downhill grade) i would sometimes speed up to 90 or more mph just to empty the battery again
     
    #14 amos, Aug 14, 2023
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