A couple of charging questions…

Discussion in 'Gen 5 Prius Technical Discussion' started by iRun26.2, Jul 3, 2025.

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  1. iRun26.2

    iRun26.2 Active Member

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    1) I accidentally fully charged my 2025 Prius last night without a reason to go anywhere today - I drove it around anyway today because I thought it wouldn’t be good for it to be sitting, for days, fully charged. Is that correct?

    2) I now have a Level-2 charger installed at my home. Is it better on the battery to use Level-1 charging when possible?

    Thanks!
     
    #1 iRun26.2, Jul 3, 2025
  2. schja01

    schja01 Senior Member

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    Remember your fully charged battery is in fact only 80% charged.
     
    #2 schja01, Jul 3, 2025
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  3. bisco

    bisco cookie crumbler

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    it's okay to leave it full and level one won't be any better for it than level two
     
    #3 bisco, Jul 3, 2025
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  4. iRun26.2

    iRun26.2 Active Member

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    I’m sorry. I guess I’m just worrying about things that the manufacturer has already taken care of for us.
     
    #4 iRun26.2, Jul 3, 2025
  5. KMO

    KMO Senior Member

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    Over the vehicle's whole life, it is worth leaving it full less.

    One of the reasons for the existence of the charging schedule, which saves you always charging immediately. Can save hours of full time every day, which will add up.

    But on a small scale, having it "full" for day due to a change of plans is not a big deal. Because it's not really full.

    And even the fastest charge the car is capable of is so far away from the sort of "fast" charge that has a significant effect on battery life, that you shouldn't worry about it.
     
    #5 KMO, Jul 4, 2025
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  6. Paul Gregory

    Paul Gregory Senior Member

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    "80%" is a matter of opinion. For many types of lithium cells, 4.2V is considered full, however, some phones charge to 4.5 volts, which drastically reduces the battery's longevity.
    The Prius engineers designed a lower battery charging level to preserve battery pack longevity. I got 12 years out of my gen 3 lithium battery pack, and only lost about 15% capacity. My Samsung phone however, only lasted a bit longer than a year, charging to 4.4V at full charge.
     
    #6 Paul Gregory, Jul 4, 2025
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  7. iRun26.2

    iRun26.2 Active Member

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    I never replaced the battery of my 2012 plug-in Prius battery. When I hit the deer that totaled it the (reason I now have a brand new 2025 model) I think it only got about 9 miles per charge. Thats about 1/2 the capacity that the battery provided when it was new. I was pretty good about not letting it sit with a full charge. However, I would almost always drain the battery to the system’s lowest point where it had as little battery left as possible. If you were driving slow and didn’t accelerate to strongly the battery could last up an additional mile (3-squares left) before the gas engine kicked on. I believe that was probably hard on the battery (leaving
    in this state every time) as it is not good to leave the battery too low.
     
    #7 iRun26.2, Jul 4, 2025
  8. bisco

    bisco cookie crumbler

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    actually, the manual recommends leaving the battery in the hybrid charge state for long term storage.
    idk why you lost 50% of capacity from new. 18 miles is way above average, and 9 way below.
    most reporting in the pip forum showed a maximum of 10-15% lost over long term usage.
     
    #8 bisco, Jul 4, 2025
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  9. iRun26.2

    iRun26.2 Active Member

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    Wow! Only 15%?! Definitely saw far more than that. My memory may be failing. Ha!

    I’m pretty sure I drove around (slowly) and got slightly over 20 miles once (I was trying to see how far I could go on one charge).

    Every summer I could tell it was a noticeably different from the previous summer. My goal every year was to get at one tank of gas that lasted 1000 miles. Last year I barely made it. This year I had decided not try that again as I might start driving dangerously slow to try and make it. Then I hit the deer (driving 70mph). That solved the problem.

    I still wonder if mine was slightly worse because I left the charge at a level that most people never did (driving slower to not turn on the gas motor when the meter first read 0 miles left of EV and turning off the car right before the gas would come on to charge the battery the battery up to the normal voltage when the car first ran out of EV power). It is hard to believe, though, that I left the battery at a level Toyota engineering didn’t account for).
     
    #9 iRun26.2, Jul 4, 2025
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  10. bisco

    bisco cookie crumbler

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    i drove mine for 11 years on 30mph roads, getting 12-14mpg from an original 14-16.
    i charged it full and used it up everyday, and sometimes 2 and 3 times a day.
    when the engine blew at 7k, it only had about 25k on it, and the battery had about 62k.
     
    #10 bisco, Jul 4, 2025
  11. Hammersmith

    Hammersmith Senior Member

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    Which is why it's a good idea to go into your phone settings and turn on battery protection. You can set the limit to 80% capacity and turn off fast and superfast charging. It's easy enough to turn back on if you're in a situation where you absolutely need 100% capacity or you need to charge as quickly as possible, but for normal use, the 80% and slow charging will add years to the life of the battery.

    (Again, this is just for a phone battery; Toyota HV battery management already does that and there's not much you can do to change it for the worse.)
     
    #11 Hammersmith, Jul 4, 2025
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  12. Paul Gregory

    Paul Gregory Senior Member

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    I was referring to the time before battery protection was available on Samsung. After my battery ballooned out of the case on my Samsung S9+, just out of warranty, I searched for apps to limit the charging level. None were available that didn't require rooting, so I used an app that would sound an alarm when the phone reached a preset level. I used that app until Samsung introduced battery protection settings. I use the maximum setting, which stops charging at the 80% level.
     
    #12 Paul Gregory, Jul 4, 2025
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  13. Paul Gregory

    Paul Gregory Senior Member

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    I'm sure it doesn't matter. Neither lvl 1 or lvl 2 produce enough current to degrade the battery.
    If you want to shoot for maximum battery longevity, try to keep in the 50% charge range.
     
    #13 Paul Gregory, Jul 4, 2025
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  14. iRun26.2

    iRun26.2 Active Member

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    Thanks! I was all set to task that very question but you answered it before I could ask it.

    I went faster tonight than any other previous drive (cause my wife doesn’t like me going on the slow side) on the interstate (65mph). That sure reduces the battery capacity quickly! I also was driving into a strong headwind. I think I only got 3.6miles/kw-hr. I still arrived home with 43% battery left. I don’t think I used any gas. I really don’t even know how to check if I used any gas.

    I know there was some kind of a comment / warning that excessive speeds challenged the battery more in my 2012 Prius PHEV. It was like draining the battery more quickly was hard on it. Is that true with the 2025 model as well? (Maybe I’m not remembering it all correctly either)
     
    #14 iRun26.2, Jul 4, 2025
  15. iRun26.2

    iRun26.2 Active Member

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    I’m glad that the charging level doesn’t matter. I absolutely love having a lv2 charger at my house! It is sooooo much faster.
     
    #15 iRun26.2, Jul 4, 2025
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