Hybrid Battery Drains Upon Startup

Discussion in 'Gen 4 Prius Care, Maintenance and Troubleshooting' started by mdmllins21, Jun 9, 2020.

  1. mdmllins21

    mdmllins21 New Member

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    Background: 2016 Prius two with 40,000 miles recently purchased a couple months ago.

    The potential issue I am seeing is when I start up the car after sitting at least 3 to 4 hours the battery will drain to 2 bars quickly (within a couple of minutes). It charges back up normally (not too fast) after driving for 5 to 10 minutes. I then don't really see any rapid fluctuation after that. I've owned the Gen 3 prius for 5 years and never saw this happen. I am wondering if this behavior is typically seen in a Gen 4. If not, any suggestions on what it might could be. Thanks!

    This may or may not be relevant. After the first week of purchasing the 12V battery went out (sat in the driveway for 4 to 5 days) and was replaced (reimbursed by dealer thankfully).
     
  2. bisco

    bisco cookie crumbler

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    welcome!
    seems normal to me. is this during warm up? the software protects the engine by using battery if available.

    from how many bars is it dropping to two?

    is the a/c on?
     
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  3. krmcg

    krmcg Lowered Blizzard Pearl Beauty

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    Have you calculated the MPGs? Low mileage value would be a sign of a problem more than the battery bars...
     
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  4. FuelMiser

    FuelMiser Senior Member

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    I believe there were two styles of traction battery in the 2016 depending on model: a NiMH and Li-Ion. Mine, the Three Touring, has the Li-Ion battery, and with just over 30,000 miles now, the battery level is rock steady. No rapid depletion at all. We had a Gen 2 with NiMH battery, and it began rapid depletion after several years and over 100,000 miles. This was a sign the battery was losing capacity and maybe balance of the cells. There are cell balancing equipment and procedures for NiMH batteries that you might want to investigate, if it turns out you have that style battery.
     
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  5. mdmllins21

    mdmllins21 New Member

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    I appreciate the responses! Yes this is during the car first starts up. The car usually drops from about 6 bars. The car A/C is usually turned on when it the car started up.

    The MPGs are where they should be (between 55-60MPG)
     
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  6. kithmo

    kithmo Couch Potato

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    I wouldn't rely on the accuracy of the HV battery gauge.
     
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  7. bisco

    bisco cookie crumbler

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    sounds like all is well
     
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  8. fotomoto

    fotomoto Senior Member

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    It did. TONS of threads on this over the years. I can also vouch that other hybrids do this too including plug-ins.
     
  9. jerrymildred

    jerrymildred Senior Member

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    This sounds totally normal. As previously mentioned, the car is borrowing from the battery and babying the ICE when you start it up. Add to that the A/C load on a hot cabin and you'll suck lots of juice from the battery which the ICE pays back after it hits a more normal operating temperature. You'll see evidence on the instantaneous MPG display. When it starts out, it'll be ridiculously high. Then it'll be crazy low while it puts electrons back in the battery. Then it'll level off.
     
    #9 jerrymildred, Jun 11, 2020
    Last edited: Jun 11, 2020
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  10. fotomoto

    fotomoto Senior Member

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    Now combine this with regular daily short drives and it equates to A) very low mpg (for a hybrid) and B) hard on a small battery. Once I learned this, swapping to plug-ins was the solution for me.
     
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