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Really Matter to Wait Until 0 Miles Left to Charge?

Discussion in 'Prime Main Forum (2017-2022)' started by stevepea, May 30, 2017.

  1. stevepea

    stevepea Senior Member

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    Was just curious about people's opinions on this.

    Is it really all that better to wait until your EV Range level is at zero to charge up again, as opposed to, say, 10 or 15 miles left, when.... (a) even at zero, the battery is still about 1/3rd full according to the graphic (buffer for HV Driving), so even if you plug in at zero miles left, the battery itself is still about 1/3rd full... (b) the battery is being charged little-by-little all the time, either when braking, or on its own in HV Mode (look at the graphics, in HV Mode the Prime tends to alternate back and forth between gas and ev, and when in gas, will constantly charge the battery a drop). Not to mention (c) if you want, there's even a Recharge setting for driving as well.

    Now I know in theory it's probably better to wait until a battery is at zero before recharging it, especially over the course of many years. But with the Prime, the battery is never really "zero".

    The reason I'm asking is while most of my commutes are 100+ miles (meaning the EV charge is always depleted by the time I get back), there are times where I'm driving around town, and I get home with maybe 4, or 7 miles left (from 31ish currently) -- and I know that my next trip will be 100 miles, so I'd like to plug in again for the next day (and not just use up the last 4 miles).

    Thoughts? While I don't know for sure, I'm assuming that there's no physical difference in what parts of the battery is used for the HV buffer (ie, no "Cels 1-20 are strictly for HV Mode buffer, Cels 21-100 are for EV Mode") -- I'm assuming it's just one big battery/chain of batteries that is treated as one unit?

    So if I have 7 miles left, and I know I'm going to be driving 85 miles tomorrow, why shouldn't I plug in tonight? :)
     
    #1 stevepea, May 30, 2017
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  2. Lee Jay

    Lee Jay Senior Member

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    No reason - just plug in.
     
    #2 Lee Jay, May 30, 2017
  3. Dale Leonard

    Dale Leonard Member

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    I plug it in anytime it is parked at home. It is a hybrid, it is built to be discharged and charged at any level. Hills, mountains.
     
    #3 Dale Leonard, May 30, 2017
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  4. bisco

    bisco cookie crumbler

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    it's not better at all, even in theory, where did you hear that?
     
    #4 bisco, May 30, 2017
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  5. alexcue

    alexcue Active Member

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    I agree, just recharge it when it's convenient to you. These batteries are never really full and never really empty. They have designed them to be pretty worry free. Sometimes we over think things based on other devices and their recommendations of how to take care of their batteries. But these are huge batteries in comparison.

    Imagine a Tesla having to wait till it's zero to recharge it because it would be bad for it? They use Superchargers on it which charge at much higher rates than we ever will on our tiny (by comparison) Prime Traction batteries. Once again my logic would say that isn't the best thing for the batteries to be subjected to, but people do it all the time, or so it seems from what I've read.
     
    #5 alexcue, May 30, 2017
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  6. Washingtonian

    Washingtonian Senior Member

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    That brings up a question that has been on my mind since buying mine. I always thought that a high current quick charge would decrease the life of a battery. Thus, a Prime charged regularly with a level 1 would have a longer battery life than one charged with a level 2. If I want my car to last as long as my Toyota Pickup, I shouldn't install a level 2 in my garage. Of course, I probably won't be here 18 years from now so maybe I shouldn't worry about it.
     
    #6 Washingtonian, May 30, 2017
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  7. bisco

    bisco cookie crumbler

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    yeah, even level 2 is so slow, the negative effect is negligible.
     
    #7 bisco, May 30, 2017
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  8. fuzzy1

    fuzzy1 Senior Member

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    How do you know that? It contradicts other conventional wisdom about batteries.
     
    #8 fuzzy1, May 30, 2017
  9. CharlesH

    CharlesH CA HOV Decal #5 on former PiP

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    In the prehistoric days of Nickel-Cadmium batteries, there was a real issue of a "memory effect", and this was mitigated by always discharging them completely, and then charging them completely. This is absolutely a non-issue for Lithium-Ion batteries, which is pretty much the only rechargeable battery chemistry used these days. And as for charging rates, the current provided by charger, even at 240V, is dwarfed by what is seen during regeneration, which happens every time you press the brake pedal or go down a hill.

    EDIT: Yikes. Of course, is also the lead-acid automotive battery. :eek:
     
    #9 CharlesH, May 30, 2017
    Last edited: May 30, 2017
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  10. fuzzy1

    fuzzy1 Senior Member

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    Don't forget lead-acid chemistry, also heavily used these days. And not just not needing full discharge, but actually lasting longer with partial discharges.
     
    #10 fuzzy1, May 30, 2017
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  11. stevepea

    stevepea Senior Member

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    Yeah, that's what I figured. And also now on rare days where I only have 2-3 hrs (instead of 5-6) between drives I know it's okay to charge the car at least a bit between them.
     
    #11 stevepea, May 31, 2017
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