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Plug-in best charging strategy

Discussion in 'Gen 1 Prius Plug-in 2012-2015' started by fberger, Jan 31, 2012.

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  1. fberger

    fberger Junior Member

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    I am lucky to have a short commute (5 miles) and multiple charging options during the day and night. I am concerned about battery longevity and want to make sure that I charge it when it is most appropriate in order to protect it.
    With electronic devices such as phones and laptops, it is recommended to never leave a Li-Ion battery fully discharged, or keep it always 100% charged, or do small charging cycles only. So personally I always try to let my phone's battery discharge almost completely at least once a week, and I often take my laptop out of its dock and use it on battery for a while, then let it recharge fully. There are also battery management programs that automate battery charge/discharge levels automatically.

    So my question is: is it better to top off the PiP battery whenever possible (in my case after every 5 miles or one third of usable capacity), or is it better to let the battery level go down to its lowest level (15 miles) and then recharge it? Again, the goal is to extend the useful life of the battery as much as possible.

    I tend to think that the less I charge it, the longer it will last. But I have a feeling that Toyota engineers used their experience with the PiP trial program and built a lot of battery management routines into the software. For instance, I thought I read somewhere that the battery pack is not managed as one battery, but individual cells can be discharged in series. It would make sense then for the computer to keep a history of how much and how often each individual cell got charged and discharged, and based on it set different priorities for each cell to be charged/discharged for each cycle. If that turns out to be the case, then it is not useful for individuals like me to try and recharge often, and more convenient to let the batteries discharge fully.

    Is there official technical information out there that would support one charging strategy vs. the other?
     
    #1 fberger, Jan 31, 2012
  2. andi1111

    andi1111 Member

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    This is not the case with Li-XX batteries. If you discharge them as far as you can, they won't last as long if you do a shallow discharge. Don't do that with laptop battery either.
    For the Li-XX battery it's better that you recharge it as often as you can. Prius will never let it charge to 100%(which also reduces battery life) or discharge below certain level. However, it will last longer if you don't fully discharge it if you have the chance.
     
    #2 andi1111, Jan 31, 2012
  3. Allannde

    Allannde Just a Senior

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    I want to support what you say above. Frequent smaller charges will not only extend the life of an LiIon battery, it will GREATLY extend the life of an LiIon battery.

    Keep the car plugged in at all times at home and use chances for an opportunity charge even if it is small.
     
    #3 Allannde, Jan 31, 2012
  4. John in LB

    John in LB Life is good

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    Just don't forget to unplug it as you are backing out of your garage... or else car life will be significantly shortened....:D

    :focus:
     
    #4 John in LB, Jan 31, 2012
  5. qbee42

    qbee42 My other car is a boat

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    The only exception to this rule is with a poorly designed charger. Sadly, some early LiIon powered tools and appliances had cheap chargers that rapidly killed batteries if left on the charger. This led many early users to believe that LiIon batteries should not be left on the charger.

    Tom
     
    #5 qbee42, Jan 31, 2012
  6. Paradox

    Paradox Prius Enthusiast / Moderator
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    I know it was a joke but in case you didn't know the car will not allow you to move it while plugged in.
     
    #6 Paradox, Jan 31, 2012
  7. john1701a

    john1701a Prius Guru

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    Prius has never allowed deep-discharging, so there wasn't ever any need to be concerned. With gas in the tank, it will always be fine regardless of how you use it. PHV shouldn't be any different.

    The only longevity suggestion I'm aware of is delaying the recharge until you're ready to leave. In other words, use the built-in timer for overnight charging so it starts early in the AM rather than immediately when you plug in.

    For those with the Advanced model, you'll be able to change when on-the-fly via the smart-phone app.
    .
     
    #7 john1701a, Jan 31, 2012
  8. Biking Maniac

    Biking Maniac Five Prius – have not sold one yet!

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    Too bad... I was planning to put my Honda 1500 watt generator in the back and leave mine plugged in while driving...Oh, wait, would that make it a Chevy Volt?
     
    #8 Biking Maniac, Jan 31, 2012
  9. fberger

    fberger Junior Member

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    John,

    Do you know why that is? What difference does it make to delay charging? If I come home with a depleted battery, isn't it better to recharge it right away?
     
    #9 fberger, Jan 31, 2012
  10. Paradox

    Paradox Prius Enthusiast / Moderator
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    John probably knows more about battery specifics but while charging immediately upon getting home isn't necessarily bad allowing the battery time to cool before charging would extend the packs life. If you need to run out again in 3 hours by all means charge (Or 1/5 hours off 240v). But if you know the car will not be used until the morning delaying the charge a while can 'help'. Again, it's not like always charging once you get home will kill the pack or anything, Toyota wouldn't sell something like that, but it's just how these kind of batteries work whether it be in your car, a cell phone etc.
     
    #10 Paradox, Jan 31, 2012
  11. fberger

    fberger Junior Member

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    I thought modern batteries had a chip on them anyways that prevented deep discharges. I thought it was better to let the device "run out of juice", since we have this protection built into the software, in order to minimize any memory effects.

    Are all cells being used in parallel as one big battery, or is the PiP using them one after another?
     
    #11 fberger, Jan 31, 2012
  12. fberger

    fberger Junior Member

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    OK, it is to let them cool then. I will definitely keep that in mind and use the timer to start charging in the morning. Is it also better to end charging a few hours before starting the car in the morning?
     
    #12 fberger, Jan 31, 2012
  13. J5A

    J5A Active Member

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    No carpool stickers for you!
    Don't forget to stock up on plenty of duct tape.
     
    #13 J5A, Jan 31, 2012
  14. Paradox

    Paradox Prius Enthusiast / Moderator
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    I don't think it matters much to really give it much thought but if you just set it to charge say between 1-4am I don't see a problem. (Assuming you're done with it by something like 10pm and won't use it till 6am or after...
     
    #14 Paradox, Jan 31, 2012
  15. iRun26.2

    iRun26.2 New Member

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    For me, I think I will often start charging as soon as I get home from work. Even if I have no travel plans for the evening, I would like to be ready (charged) to go in case I think of an excuse to go someplace. It won't take much of an excuse to drive after supper (at least not at first).
     
    #15 iRun26.2, Jan 31, 2012
  16. Allannde

    Allannde Just a Senior

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    Absolutely. This makes sense to me, also.

    Good habits pay off far more than trying out out guess the battery on a daily basis. And the benefits of many small charges when possible are greater than the possible dangers of charging a warm battery. Of course some people will save by charging at off peak hours which is a consideration.

    But Toyota has a fine record with it battery management systems which is a HUGE plus. It is that, not a "chip in the battery", which is the protection which counts.
     
    #16 Allannde, Jan 31, 2012
  17. john1701a

    john1701a Prius Guru

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    That suggestion was given during the reveal.

    If I know I'll be heading out in the evening, I'll be recharging as soon as I get home too.
     
    #17 john1701a, Jan 31, 2012
  18. usbseawolf2000

    usbseawolf2000 HSD PhD

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    The battery doesn't like to be stored at full charge for a long period of time. It is preferable but you don't have to go out of your way to do it.
     
    #18 usbseawolf2000, Jan 31, 2012
  19. Allannde

    Allannde Just a Senior

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    usbs,

    That is correct but may be misleading. Most people use their cars regularly which is not storage. During usage there is at least some depletion which avoids the problem which you present. Further Toyota's battery management system will not permit a really full charge of the sort you reference.

    If long term storage is planned, special preparation is in order and that should probably include a less than full charge as you say.
     
    #19 Allannde, Feb 1, 2012
  20. andi1111

    andi1111 Member

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    Li-XX batteries have no memory effect.
     
    #20 andi1111, Feb 1, 2012
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