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Battery draining fast but charging slow

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by NicholasW, Sep 27, 2011.

  1. NicholasW

    NicholasW New Member

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    Just bought a 2006 Prius, ironically only has 31,000 km on it.

    My question is, recently, mostly today, i noticed the battery has been draining quite fast. I was at 2 bars from full(or 3? whatever is pre "green") and probably 5-10min later i was 2 bars and the gas engine was running. Whatever seemed odd, maybe the traffic was a little slower today.

    However i started driving 80kph and it took over 5 minutes for the car , without battery running, to bump from 5 bars up to 6. The electric motor was literally not driving the whole time, it was strictly gas the whole 5 min.

    Is this normal? What should i be looking at if it is not?

    I was also considering taking this car for an inspection at the dealer just to ensure everything is okay before winter hits.

    Thanks again let me know if i need anymore information.
     
    #1 NicholasW, Sep 27, 2011
  2. cwerdna

    cwerdna Senior Member

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    During the bolded part, was the gas engine on at all or were you in electric the whole time and/or was it mostly stop and go? If in electric, that sounds normal to me. The drain will be even faster if the AC is on. (If stopped and comparing AC on vs. off, the drain will look REALLY fast w/AC on.)

    As for the latter, that doesn't sound abnormal.
     
    #2 cwerdna, Sep 27, 2011
  3. efusco

    efusco Moderator Emeritus
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    I'm not reading anything too worrisome in what you're saying happened. The battery isn't always trying to charge up and will often settle into the 5-6 bar range with little movement during normal driving. During low speed driving when the ICE isn't running the SOC can go to 1-2 bars, esp. right after start up.

    When a battery is going bad, typically, you'll see massive rapid swings in the SOC in a more unpredictible manner.
     
    #3 efusco, Sep 27, 2011
  4. qbee42

    qbee42 My other car is a boat

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    The Prius tries to keep the battery in the middle range, just a touch toward the top. This is so it has juice to provide power, but room to absorb power from regenerative braking. Normally you will never see green, although green is not uncommon in cold weather when the engine needs to provide heat, or descending long hills when regenerative braking will top off the battery.

    Tom
     
    #4 qbee42, Sep 27, 2011
  5. bisco

    bisco cookie crumbler

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    what was the driving like as the battery became depleted and what accessories did you have on?
     
    #5 bisco, Sep 27, 2011
  6. seilerts

    seilerts Battery Curmudgeon

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    #6 seilerts, Sep 27, 2011
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  7. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator
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    Nicholas. You're in for some chilly weather, 6Ëšc mornings. If you're running the heater (which I would) I have no doubt that the engine would run and most likely charge the battery to near full. As Tom said, it will rarely get to the full-green and when it does it normally doesn't hold it for long.

    But then, in the evening, when it gets up to 13 - 14Ëš these days, you're probably not running the heater anymore and if, like you said, traffic was a little slower, it's possible that you were travelling on battery power, like Evan said.

    So I would have to say that it all sounds normal so far. You should provide some more information about what type of driving you were doing when you saw the battery drop, like cwerdna said. Please keep in mind that the 2006 Prius isn't intended to run on battery-only power for long distances and that if you are cruising along - or stop-n-go - for about a mile you can deplete the battery pretty good.

    Also, please take a few minutes to complete your profile. Location information really helps us zero in on any problems due to terrain and/or climate. For example, someone asking your question in Florida would have a completely different issue than someone farther up North. ;-)
     
    #7 TonyPSchaefer, Sep 27, 2011
  8. NicholasW

    NicholasW New Member

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    Okay that sounds good, wasnt sure what to consider was excess or not.

    I had no accessories other than radio on.

    Okay i will pick up a voltmeter from my old folks place and give it a test. I can only assume it's the original 12V battery, i will give it a check.


    ahahah. 6Ëšc mornings sound amazing. I am more expecting -15C to -30C lol. I filled it out, i'm from Calgary. It should be "warm" for another couple months. then i expect to have the heater on every time i drive.



    Thanks for all the help, i have read through a bunch of the newbie stuff. Not sure what was speculation and what was just me being unsure.
     
    #8 NicholasW, Sep 27, 2011
  9. cwerdna

    cwerdna Senior Member

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    You hadn't answered the rest of my question though...
     
    #9 cwerdna, Sep 27, 2011
  10. NicholasW

    NicholasW New Member

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    Oh sorry i was answering someone else.

    It was stop and go mostly, maybe a little more "creeping" than usual, i don't know. I just had my battery a fair bit lower than normal so was worried.

    Also it's usually never hot enough here for AC. At least in my opinion, 30C isn't hot enough to justify even bothering turning it on lol. I doubt it will ever get used, unless i have guests in the car i suppose.
     
    #10 NicholasW, Sep 28, 2011
  11. cwerdna

    cwerdna Senior Member

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    For stop and go, the behavior you saw is normal. And, as I said, if you do use the AC at all, the drain will be MUCH worse.

    As a side note, if it gets cold, if you have the heater on, the ICE could turn on to provide cabin heat if the ICE cools too much. On the 2nd gen, if coolant temp <=145 F and heat as on hi w/fan above off, the ICE will run to provide cabin heat.

    You can monitor the # amps going in and out of the HV battery, its SoC in % (what's shown on the MFD isn't 0-100%, see Prius Palm Mileage Simulator), coolant temp, etc. w/something like a ScanGuage II (ScanGauge - Trip Computer + Digitial Gauges + ScanTools). I've got an SG II.
     
    #11 cwerdna, Sep 28, 2011
  12. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator
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    I knew it was around here somewhere. I created a thread a while back because I was finally frustrated with my evening commute. There was a 4-way stop that would back up for a mile and had me creeping very slowly for up to 15 minutes. This would drain my battery and eventually would result in the ICE kicking on and me idling. very frustrating.

    They've since installed a round-about and everything is fine.

    Anyway, here's my thread. If you only read my original post, you'll recognize what happened to you and understand that though no fun, it's normal under the circumstances: http://priuschat.com/forums/gen-ii-prius-fuel-economy/66167-why-does-your-commute-suck.html
     
    #12 TonyPSchaefer, Sep 28, 2011
  13. 2009Prius

    2009Prius A Wimpy DIYer

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    Makes me wonder if it makes sense to intentionally do some harder braking to charge up the HV battery if one is anticipating a long stop-and-go traffic ahead.
     
    #13 2009Prius, Sep 28, 2011
  14. qbee42

    qbee42 My other car is a boat

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    No, that makes no sense whatsoever. Regenerative braking is a very inefficient way to charge the battery.

    Tom
     
    #14 qbee42, Sep 28, 2011
  15. uart

    uart Senior Member

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    What about force charging it in "P" if you happen to be at a dead stop in the queue?
     
    #15 uart, Sep 28, 2011
  16. 2009Prius

    2009Prius A Wimpy DIYer

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    So is engine idling during stop and go. So the question is what's the best strategy to optimize overall efficiency.
     
    #16 2009Prius, Sep 28, 2011
  17. qbee42

    qbee42 My other car is a boat

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    The engine doesn't idle during stop and go. The engine stays off until the battery needs to be charged, and then runs at an optimal level for recharging.

    The best strategy to optimize overall efficiency is avoid stop and go traffic. If you are forced to drive in stop and go, the best strategy is to allow the Prius to do its thing and don't try to outsmart it. If you have an EV button you can judiciously use it to hold off short bursts of the engine, but the key word is judiciously.

    Tom
     
    #17 qbee42, Sep 28, 2011
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  18. AustinP

    AustinP New Member

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    Sounds like a problem we started having at about 165K miles. Sometimes the car would drive very sluggish, and the battery indicator would show almost no charge; and it was very very slow to recharge on a downhill. Next day, the car would drive fine. A couple of times, but not always, it seeed to be triggered by running the AC in 100+ degree weather. Twice it seemed to be after a heavy rain. It happened both before and after we got our new 12V batery in the trunk.

    No indicator lights ever came on.

    14 months and 25,000 miles later, three separate dealerships have failed to find the cause. The last two have assured me that the hybrid system battery checks out okay.
     
    #18 AustinP, Oct 16, 2011
  19. seilerts

    seilerts Battery Curmudgeon

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    It is your battery, it just hasn't quite given up yet. I bet if you let it sit for a week and measured the block voltages, you'd have 1 or more blocks that were more than 0.5V less than the others. Thing is, the car won't code until that difference is 1.2V. As soon as you start the car, the battery ECU acts to bring all blocks to the same voltages, so by the time you drive a dealer, the voltages are in perfect alignment. A load test may or may not reveal the weak blocks either.
     
    #19 seilerts, Oct 16, 2011
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