Is it worse to keep battery full overnight or empty overnight?

Discussion in 'Prime Main Forum (2017-Current)' started by panpaper, Oct 24, 2018.

  1. panpaper

    panpaper New Member

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    Before I get started, I know that when the car says 100% battery, it's not actually at its full capacity. Similarly, when the battery reads 0%, it also doesn't mean the battery is actually empty. All electronics manufacturers leave a little bit of room above and below the reported levels because having the batteries reach those extremes will drastically reduce its lifespan.

    That been said, I have been scheduling charging for my prius prime to finish before the time I normally leave home every day. This is to prevent the battery staying at "100%" throughout the night. I also started to wonder if it's worse for the battery if I leave it at "0%" throughout the night, until the scheduled charging time begins. Does anyone have any kind of insight to this?

    To clarify, I'm talking about the bigger battery that can be used for EV mode, not the smaller battery that serves the regular hybrid functions.
     
  2. Tideland Prius

    Tideland Prius Moderator of the North
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    Welcome to PriusChat!

    There is only one hybrid battery (it's just electronically partitioned into the EV part and the hybrid part.. no physical difference).

    If I had to pick between the two, it's worse keeping it full. It's better to keep it near the hybrid/EV crossover area and charge up such that it's full when you're ready to go (i.e. use the "Charge by" timer and not the "start at" timer).

    In all honesty, the 100% SOC is about 80% true SOC which is roughly the max that Li-Ion chemistry batteries like to be for longevity. (you'll see the LEAF and Tesla have options for 80% charge)
     
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  3. bisco

    bisco cookie crumbler

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    full
     
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  4. huskers

    huskers Senior Member

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    I keep mine full as often as possible. You never know when you need to go. Like I need to go now.
     
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  5. KP7

    KP7 Member

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    But isn't that the point of a PHEV vs a BEV? It's always ready to go.

    I dont have the page reference but I'm pretty sure the manual says to leave it on full charge for as limited a time as possible. So as Tideland said use the charge by scheduling and you're all set.
     
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  6. The Electric Me

    The Electric Me Go Speed Go!

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    So full or empty, the answer is really neither?

    What is the hybrid/EV crossover area?

    And is it for loading and unloading? (just kidding).
     
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  7. bisco

    bisco cookie crumbler

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    it is when the battery range estimate is gone (empty) and the icon displays like a non plug in prius.
    basically no wall charge left.
     
  8. triggerhappy007

    triggerhappy007 Active Member

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    Worse to keep it full overnight. So use scheduled charging.
     
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  9. Spidey71

    Spidey71 Member

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    I agree. And now that I've switched to "charge by" I've also noticed the distance I'm getting before it drops from 100% to 99% has increased. It used to drop to 99% before I got to my neighborhood stop sign. Now, I'm getting an extra 150 - 200 yards past the stop sign. Not that scientific, I know. But it was enough distance gain that I noticed!
     
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  10. Tideland Prius

    Tideland Prius Moderator of the North
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    You really want to know? Once you've crossed it, there's no going back. o_O


    j/k. Basically drain the EV portion of the battery so you can no longer enable EV mode. I think the manual does say to leave the car in that state of charge if you're parking it long term.
     
  11. panpaper

    panpaper New Member

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    I didn't know that! I thought there was one smaller battery somewhere below the console, and a bigger battery below the trunk area. I really appreciate your input and you seem really knowledgeable about this car, but may I ask where did you get the information about the SOC being at about 80% when the car shows 100%?

    Thanks!
     
  12. citiprius

    citiprius Active Member

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    My Lenovo laptop has some kind of "smart charge" mode, which keeps the battery at around 60% to prolong the life of the battery. It is recommended to use that mode if the daily usage is plug-in in most of the time.

    I'm not sure if that same theory applies to the Prime battery?
     
  13. schja01

    schja01 One of just a few in Chicagoland

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    All of my Lenovo’s are in docking stations and keep the batteries between 25 and 85 percent. That was optional.
     
  14. Tideland Prius

    Tideland Prius Moderator of the North
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    No. (Hopefully not to confuse you, but maybe you were looking at a diagram or image of a Prius Prime with the solar roof option - that is only available in Japan and Europe. They have an extra battery beneath the rear seats for the solar panel to charge up and then that battery charges the main HV battery. For US models, we only have the one large one).

    @john1701a 's videos. He has an app called the "Hybrid Assistant". In the screen capture below, I circled the car's battery meter which shows a full charge. In the bottom right, he overlays the Hybrid Assistant interface in the video. I highlighted the battery SOC which reads 82%.

    upload_2018-10-29_22-45-21.png

     
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  15. pizzabad

    pizzabad Junior Member

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    Yes it’s true. I’ve a European Prime : PHV with solar roof. When the SoC seems to be full (100 %) indicated by the car, the real SoC is near 83,5%.
    The limit EV /HV is near 14%.
    In HV mode, the SoC has to stay above 9 %. In this case, the ICE runs faster to charge the battery.

    I can see these informations need to Hybrid Assistant.

    Excuse me. I’m French so my English is not very good...
     
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  16. jaqueh

    jaqueh Active Member

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    I’ve lost about 10% capacity over 20,000 miles, and my battery is frequently in the hybrid zone as I don’t have access to charging at home. Either that caused my battery loss or the fact that the battery has really poor thermal management.
     
  17. pizzabad

    pizzabad Junior Member

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    @jaqueh : 10% ? Are you sure ? How many miles can you do with a full charge in summer ?
     
  18. jaqueh

    jaqueh Active Member

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    Yeah. It’s a bit less but I can only put in about 5.6 kWh vs the ~6kwh original capacity. I wish I knew about how likely the battery was going to degrade in Toyota phevs.
     
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  19. bisco

    bisco cookie crumbler

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    i think that is just the definition of lion batteries. initial capacity quickly drops, then stabilizes.
     
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  20. bresna

    bresna Active Member

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    My capacity seems to have taken a little hit in the past few weeks. I thought it was due to colder temps, but even when it's warmed up, I'm not getting more than ~28.5 miles showing up on the dash after a full charge. I was showing ~33 before this recent & sudden drop. Could still be temp though so I'm not too worried.

    FWIW - My commute & charging habits have not changed in all of the previous 48,000 miles of driving.
     
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