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Slow charging (110V) impact on battery health ?

Discussion in 'Technical' started by eggy, Aug 3, 2017.

  1. eggy

    eggy Member

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    Apologies, if this has been discussed before, but I couldn't find anything.

    I was wondering, whether constantly charging a MS battery on a 110V outlet would have a negative impact on the health of the battery long term considering that the charging process and hence the stress on the battery lasts much longer (timewise) compared to charging on a 11kw/22kw-charging station or even at a supercharger.
     
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  2. KarenRei

    KarenRei KarenRei KarenRei KarenRei KarenRei KarenRei

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    Just the opposite. Slow charging leads to the longest longevity for batteries. Just be aware of how slow it is - remember that a simple hair dryer or mini space heater uses up nearly 100% of the capacity of a 120V 15A socket, and you're looking to charge a car off of it.

    If your goal is maximal longevity:

    * Get as large of a pack as you can afford
    * Charge at as slow of a rate as you can
    * Avoid supercharging to the extent that you can.
    * Limit your charges, to try to cycle around the middle of your pack's charge range when you drive (aka, fill to 70% full, drive to 40% remaining)

    That said, longevity is not proving to be a problem for most users. Tesla put a lot of work into battery management for this purpose (unlike Nissan, with the passively cooled battery "box" on the Leaf which often degrades badly in just a couple years).
     
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  3. TexasEV

    TexasEV Well-Known Member

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    Yes you are correct.
     
  4. dhrivnak

    dhrivnak Active Member

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    While I agree with most of what you have said. the charging to 70% is a double edge sword as keeping the battery balanced is also important as your battery is only as strong as your WEAKEST brick. In the Roadster the balancing only happened above 82% and a number of owners have experienced much shorter range due to an unbalanced pack. So if you set the charge level to 70% I would charge at least to 90% once a month and leave it set for several hours.
     
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  5. KarenRei

    KarenRei KarenRei KarenRei KarenRei KarenRei KarenRei

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    Quite true, and I should have mentioned that. Li-ion SOC measurement is generally based on coulomb counting with periodic recalibration, and periodic equalization is important as well.
     
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  6. HKRied

    HKRied New Member

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    I see knowledge here. I'm retired with a 90D. I have a 240 plug and typically charge to 80% (~240 mi) and run down to 100-125 mi every few days before plugging in. On a daily basis, it's unplugged more than it's plugged in. I don't put on a lot of miles and sometimes go days parked in the garage. Although, as the seasons change, I'll travel 1300 miles north/south and set it to 100% for the trip. Same for occasionally vacation travel. So here's the Question: Since I don't drive a lot daily, would it make sense to switch to the 110v adapter for normal day-to-day? I'd still probably charge every other day or so most of the time, 10 hours overnight at 4mi/hr for 40 miles. Feel free to tell me I'm in the weeds here. I know it's minutiae. But maybe I need to stretch my battery life so I get the FSD I paid for. :)
     
  7. brkaus

    brkaus Active Member

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    Instead of 120v, I'd stay with 240v and set the amps way down.
     
  8. chipmunk

    chipmunk Member

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    #8 chipmunk, Aug 4, 2017
    Last edited: Aug 4, 2017
    You should know though, that charging more slowly is generally less efficient and results in more energy being spent on running the electronics that charge the car and maintain the temperature. It's something like 80% efficient, as opposed to 90% efficient on a decent amperage 220 volt circuit. Source

    Also, I wonder if there is any impact on the longevity of the charger itself?
     
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  9. KarenRei

    KarenRei KarenRei KarenRei KarenRei KarenRei KarenRei

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    That might be a bit distorting. The vehicle uses some power whether it's charging or not. Obviously the slower you charge, the more the percentage of the total power input will go to parasitic losses, but that's not the fault of charging - that's just due to how much time the parasitic losses are counted for.

    As a general rule, slow charging is the most energy efficient manner. Without any parasitic losses accounted for (fans, climate control, etc), slow-charged li-ions can be over 99% efficient - but fast charged li-ions lose a lot to heat, often with sub-95% and sometimes sub-90% efficiency.
     
  10. chipmunk

    chipmunk Member

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    I understand what you're saying, but parasitic loss can't account for all of that. People are seeing like a 20% variance. It would take a long time to lose that much charge in a car just sitting there unplugged and off.
     
  11. HKRied

    HKRied New Member

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    I'm new here and the response is disappointing (maybe just over my head). I'm a basic computer geek but know nothing of battery tech. I guess I'll stick with 220v.
     
  12. TexasEV

    TexasEV Well-Known Member

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    Actually make that 240V
    Here's Tesla's recommended installation of the 240V 50A outlet:
    https://www.tesla.com/sites/default/files/downloads/US/universalmobileconnector_nema_14-50.pdf

    The only reason to even think about charging a Tesla at home using 120V is if installing a 50A circuit is cost prohibitive. And if that's the case, give serious thought if a Tesla is really for you.
     
  13. KarenRei

    KarenRei KarenRei KarenRei KarenRei KarenRei KarenRei

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    Now now, not everyone owns their own property and can make modifications. And for the record, it's perfectly reasonable to say 220V, 230V, or 240V. They're just nominal voltages anyway, the actual voltage often deviates significantly from that. And US voltages tend to run below their nominal. If I recall correctly, the actual US average is something like 117V/234V. You might be a couple volts over 120V if you're close to the pole, or even below 110 if you're far away with bad wiring. The high voltage split phase outlets are ostensibly double that of the single phase, but they can sometimes measure a bit less since the phases don't perfectly match up.

    Where I am we're a nominal 230V. And usually hover around that mark. US split-phase voltages are in practice pretty similar.

    That said, I agree with you that if they can, it would be advisable to install a higher power socket. But if you have the short-range variant Model 3, there's not much point to going over 30A, because the charger can't take more than that.
     
  14. TexasEV

    TexasEV Well-Known Member

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    in the US it's not reasonable to say 220 or 230V. Nominal residential voltage has been 240V for at least 50 years.
     
  15. HKRied

    HKRied New Member

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    How do you the amps?
     
  16. JHWJR

    JHWJR Member

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    It seems that the chargers on the car take a certain amount of energy to operate. Your car gets what's left over. With 110v, there is not as much leftover as with 240v. Therefore, 240v is more efficient as a higher percentage of the current reaches the batteries. And the difference can be significant. But if 110v is all you got and all you are going to get, your biggest challenge will be getting enough in the battery to get you where you need to do, not the extra $2 perhaps that it takes to get a full charge.
     
  17. brkaus

    brkaus Active Member

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    While you are at the location in question, bring up the charging screen on the center console.

    Lower right corner of that screen shows amp settings. Just turn it down with the arrow.
     
  18. chipmunk

    chipmunk Member

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    Absolute agree. I charge on 110v somewhat often, but all things considered I think 220v is preferable if available. Also, since the topic is longevity of the battery, you can afford to keep the battery at a lower state of charge knowing you can quickly top up when needed.

    I'm guessing maintaining a lower SOC will extend the battery life more than charging slowly.
     

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