Is Hybrid Battery the Culprit to my Poor MPGs?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by ZBrink, Jul 21, 2020.

  1. ZBrink

    ZBrink Member

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    Trying to figure out why I have poor MPGs in my 2010 Gen3. Is it my hybrid battery on it's way out? See pics of Dr Prius App tests.

    At 135k, I currently average 39 to 40 mpgs but started at 47 mpgs at 30k. I drive it daily and it rarely sits.

    No check engine lights. 400 miles ago I cleaned the intake, throttle body, MAP sensor and the EGR valve, cooler and all components. All were very dirty or clogged. 12V battery is solid. Tires are Michelin Defenders set at 35 PSI. Spark plugs were changed at 120k.
     

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    #1 ZBrink, Jul 21, 2020
    Last edited: Jul 21, 2020
  2. Raytheeagle

    Raytheeagle Senior Member

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    How long has it taken to put in the 400 miles?

    Also, how frequently is your Prius taken out for a drive and for how long?

    Could be other reasons for the poor mpg's, but check the obvious stuff first;).

    Getting the egr circuit cleaned is a big step though :).

    Good luck and keep us posted(y).
     
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  3. ZBrink

    ZBrink Member

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    It's driven daily, a minimum of 20 miles. It took less than 2 weeks to put 400 miles on it.

    I believe I have checked all the obvious stuff which is why I'm asking about the hybrid battery. If I missed something, please let me know.
     
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  4. Raytheeagle

    Raytheeagle Senior Member

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    How fast does the battery cycle full to empty?

    Did you pull the 12 volt lead when doing the above work?

    Tire pressures and how old are the tires?

    Any other recent maintenance?

    Chasing mpg's can be difficult as there are a lot of variables:cool:.

    I also invested in the Hybrid Automotive equipment for our old 2010 to maintain the HV battery and it worked well for the over 2 years that I had it paired to our Prius:).

    It definitely helped the mpg's while ensuring other factors were accounted for;).

    Good luck and keep us posted (y).
     
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  5. ZBrink

    ZBrink Member

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    The Michelin defenders are 18 months old and I run them at 35 PSI. I know that can account for a little bit of the mileage but I have always run them at that PSI and have always run this make and model of Tire. MPGs have slowly dropped over the last 100k.

    Spark plugs we're changed at 120k. Oil changes and tire rotations are done regularly at the dealer. I've run two cans of seafoam both in the fuel tank and through the intake over the last 1200 miles or so.

    The 12V has not recently been disconnected.

    I do not know how fast the hybrid battery cycles from full to empty. If you know of a way to tie more test this, please let me know.
     
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  6. Raytheeagle

    Raytheeagle Senior Member

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    If you sit in traffic, or in a drive thru line, how fast does the battery drain and the engine kick on?

    When I was in traffic is when I noticed battery degradation which prompted the investment in the Prolong equipment.

    But battery degradation can explain mpg loss.

    I'd eliminate the low hanging fruit and plan for what solution you want when the hv battery does fail.
     
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  7. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    Have you cleaned the battery fan and associated ductwork?

    Honestly it does sound like the hybrid battery is tiring, but you might squeeze it a little longer.

    Consider a used genuine battery out of a wreck. car-part.com can lead you to parts recyclers.
     
  8. royrose

    royrose Senior Member

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    40% on the Dr. Prius test is pretty low, so you are near the brink. For comparison, I have a 2010 Prius with just under 100,000 miles that gets 65 to 70% on the Dr Prius test. My driving is less consistent than yours, so I don't see why mine is doing better. I also get worse mileage than I used to but not as bad as yours, about 42 mpg average. It is mysterious why some batteries do worse than others.
    Your daily use should be good for your battery.

    Since none of your blocks have actually failed, a Hybrid Automotive prolong system might buy you some time, but I don't know if it is worth investing that much in your weak battery.
     
    #8 royrose, Jul 21, 2020
    Last edited: Jul 21, 2020
  9. ZBrink

    ZBrink Member

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    I have not cleaned the battery fan and duct work but plan to this weekend. I can't imagine that giving me a boost mpgs.

    I'll do a Green Bean before I do another used battery.
     
  10. ZBrink

    ZBrink Member

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    Have you used the Pro Long system? Will they boost mpgs back up? I'm just recently learning about their system. It's half the cost of the new battery and seemingly a lot of effort vs just buying a Green Bean battery.
     
  11. ZBrink

    ZBrink Member

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    What were your mpgs before you added the Pro Long system vs after? What changes and effects did you see?
     
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  12. Grit

    Grit Senior Member

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    :ROFLMAO::ROFLMAO::ROFLMAO::ROFLMAO::ROFLMAO::ROFLMAO::ROFLMAO::ROFLMAO:
     
  13. ZBrink

    ZBrink Member

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    Can you please elaborate?
     
  14. Raytheeagle

    Raytheeagle Senior Member

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    Here is the thread I started for my specific situation on the topic:):

    2010 Prius II HV Battery Reconditioning

    More light reading ;).

    But if I recall correctly, I was at 44-46 mpg prior to the Prolong equipment use. Hope that helps(y).
     
  15. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    You'd be surprised. If the battery temperature isn't in the range the computer likes, it will silently limit the battery's participation in your propulsion, and the general result is more fuel burned.

    Personally I see less risk & hassle in the junkyard battery vs. the work of a repacker like greenbean.
     
    #15 Leadfoot J. McCoalroller, Jul 22, 2020
    Last edited: Jul 22, 2020
  16. ASRDogman

    ASRDogman Senior Member

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    Green Bean IS a used battery......
    The Prolong system is about $650..... A lot less than a USED greenie beenie battery... :)
     
  17. ZBrink

    ZBrink Member

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    Green Bean batteries are fully reconditioned, with a full warranty and is $1650. Junk yard batteries are a coin toss and $900 for a used one around here. As far as Prolong, I don't fully understand what it will do for me. If it's not guaranteed to significantly increase my mpgs and save my battery for 5'ish years, what's the point?

    First I need to know if the battery is my problem and I need more knowledge on Prolong.
     
    #17 ZBrink, Jul 22, 2020
    Last edited: Jul 22, 2020
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  18. ZBrink

    ZBrink Member

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    I read a bit through your thread and that seems like A LOT of continuous work. Do you have to use it regularly to keep up those mpgs?
     
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  19. Raytheeagle

    Raytheeagle Senior Member

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    Once every six months I would do a top end balance, then every thanksgiving, I would do a 2 cycle reconditioning;).

    That isn't that frequent in my book, and was scheduled:).

    Had I kept the 2010, I think it would have been fine with the same battery and the equipment. If I would notice any issues with it, I'd have the right equipment available to address it(y).
     
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  20. royrose

    royrose Senior Member

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    How long do you hope to keep the vehicle and how many miles will you put on it? That makes a difference in weighing the options which all have trade offs.
     
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