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Does charging multiple times a day reduce battery life?

Discussion in 'Model S: Battery & Charging' started by GasKilla, Nov 11, 2015.

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  1. GasKilla

    GasKilla No Gas Know Peace

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    I have the option to charge at work using a 120v outlet, after work where I exercise 240v, then when I get home on 240v. Will charging multiple times a day (on different voltages) effect battery life?

    Should I only charge a few times a week when I really need to add range? Honestly I could get by only charging 3x a week. I certainly want to extend the life of my battery and would like to know what the best practice would be.
     
  2. CHG-ON

    CHG-ON Still in love after all these miles

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    Based on my reading, I don't think you will have an issue. Tesla recommends being plugged in whenever possible. My understanding of their batteries is that keeping a relatively even SOC is best for the battery. I drive 20mi/day and plug in every night, charging to 90%, except when I forget. I have also run the battery down pretty low occasionally and I have seen no difference in my rated miles after a year.

    The general consensus is to not worry about it. The BMS is quite good.
     
  3. GasKilla

    GasKilla No Gas Know Peace

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    Is a 90% charge recommended over 80%?
     
  4. Canuck

    Canuck Active Member

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    That depends how much driving you do. If you can stay within the daily driving range with an 80% charge, then 80 is better. If 80 makes you fall real low, then 90 is better. The key is not too low and not too high, unless needed, then drive right away when charged full, and recharge right away when empty.
     
  5. Lesifass

    Lesifass Member

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    I think the battery loves 50%. So try to be as close to 50% as possible (when possible) if you really want to maximize battery life. If you need 10% for a roundtrip, it's probably best to charge to 60% right before you leave, then let the car sit at 50% when you return. (Edit: This might confuse the state of charge estimation algorithm though, so the displayed miles may vary and make it seem like you're losing battery capacity. Going close to 0% and close to 100% state of charge should fix that if it happens.)

    But that's not required, charging to 80% repeatedly every day won't kill your battery. The only thing you should not do is let the car sit for a longer time when its state of charge is really low or really high (> 90%).

    In fact, when you use the car, the battery will go through a "micro charge cycle" every time regen kicks in. :)
     
  6. TexasEV

    TexasEV Active Member

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    Tesla recommends to plug in whenever you can, so what you describe is the recommended thing to do rather than something of concern. The cars used to be delivered with a card inside showing a car that is plugged in and said "A connected Model S is a happy Model S". I think they should resume doing this, it would save a lot of questions.

    Your question could also be answered by saying RTFM. The recommendation to plug in whenever you can is in the manual. Several times. In bold print.

    I would add don't be obsessed with state of charge as the above posts might suggest. Charge however much you need to be comfortable with including possible unexpected trips, only charge to 100% when you need to and don't let it sit there, otherwise just enjoy you car and let the battery management system manage the battery.
     
  7. apacheguy

    apacheguy Sig 255, VIN 320

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    Note that while the cells might like 50%, reducing your daily charge limit below 80 will really throw off the range estimate and might cause balancing issues.

    IMO, if you only drive 10 miles to work and charge at night, there is no reason to charge the battery back up to 90% while at work.

    With all due respect to the manual it vastly over simplifies things and isn't really useful at all to folks who understand the basics of Li Ion batteries.
     
  8. TexasEV

    TexasEV Active Member

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    I think an oversimplification of "plug in whenever you can" is just what most mainstream buyers need. The vast majority of buyers don't understand the basics of Li ion batteries and don't have any reason to learn, nor should they. And what people think they know about them may not apply to Tesla's implementation of it anyway with its battery management software. That's why the postcard was so effective-- people may not remember what they read in a manual but do remember the clever "A connected Model S is a happy Model S".
     
  9. GasKilla

    GasKilla No Gas Know Peace

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    I think it is Plugin America that has a saying "ABC" which means "always be charging", sounds like the way to go with the Tesla. I have a Leaf and I plugin whenever I can and have lost one capacity bar (about 8%) after 3 years. The Tesla is in production and I plan to keep it for the long haul. I'd like to maximize the battery life. Right now my commute is about 40 miles round trip.
     
  10. BertL

    BertL Active Member

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    OP, IMHO one can go nuts reading a myriad of opinions on the subject. I tend to be a research hound, and honesty the mostly well-meaning people that voice opinions on sites like this are great, but it was also over-whelming especially when I spent nearly 3 months reading, re-reading threads, and thinking about converting from ICE, and in my case 10-years of also driving Lexus Hybrids. If a had to be a PhD to understand lithium-ion characteristics, I (and likely many others) would not buy Tesla, but some like to deal with that sort of thing. OK for them ...but as a new MS owner, where I have landed, and where I'd be if I were in your situation is:
    • I'd only use 120V as a last resort. It's extra work to connect and disconnect your UMC to receive perhaps 3-4 mi/hr of charge, and to whoever is paying for the electricity and from an environment perspective, 120V is as inefficient as you can get from a Tesla charging perspective. 120V is what I would use if I had no range left to get to something faster and more effecient, e.g. If I owned a cabin in the middle of nowhere that had only 120V and I was going to be there a few days, that would be OK so I had enough charge to get home or to a Supercharger.
    • Why not just plug your MS in at home every time you arrive and have no plan to run another errand that day? That's what I do. I have my MS set so it will begin charging if it needs it at 12 midnight every day, and with the electrical rate plan I converted to, I pay the lowest rates 12AM-5AM, and in theory could recharge my "nearly empty" 90D (wth dual chargers and an 80-amp HPWC) to almost 100% if I had to before the rates go up again at 5AM every day. If you plug in MS, it will never over-charge, assuming you leave your default max charge to say 90% (another point others may give you varied opinions on, but your MS comes with that as the default, and it's what I use)... Of note here, is let's say I leave my MS plugged in for multiple days and don't drive it in-between... MS will bring the charge up to 90% the first night, but it won't start a full charge cycle the next night to only replenish the 1-2 mile vampire loss, and only starts a true charge cycle at some later point... It's proven to be smarter than I need to be. I'm letting the engineers that designed my MS, established defaults that were programmed and delivered as part of the firmware in my MS, who also wrote the Owners Manual, and who are responsible for standing behind the 8-year traction battery warranty that is likely longer than I'll own my favorite toy, to be my guide for the most part...

    As much as a technicial guy like myself can overthink things (and oh yes, I have many times), I'm trying not to with my MS for the most part when it comes to this whole charging subject. I don't live in the Arctic or in extremely hot climates like I once did, nor do I park my car at the airport for weeks at a time like I once used to -- all being possible reasons one may want to TEMPORARIALY override some defaults Tesla has, depending on ones interpretation and speculation of Tesla's precise engineering and software/firmware design that only they really know the facts to. IMHO, Tesla is using the Roadster, MS and MX to ease their way into how to deal with volumes more EVs being sold per year when M3 and others come to be. Some of the defaults in latest gen MS/MX firmware didn't exist in earlier gen MS when they were delivered, but they do today as Tesla has learned what is more optimum. I'm sticking with the KISS principle as I think Tesla is trying to design their product for, and how Tesla must want all owners to deal with their EVs in the long term so they can reach the masses -- Keep It Simple Stupid. I plug my MS in when I get home every time unless I know I'm leaving for another short errand later that day. I let my MS manage itself, knowing it will be at 90% charge each morning when I wake up, and only think about charging away from home if I really need it because of extended range... not just because I could plug it in and let someone else pay for the little electrical top-off I would be avoiding while I'm out and about. For the daily range it appears you need, I bet you could operate much like I am, enjoying my MS, and really only thinking about charging and range when I have a road trip planned.
     
  11. Canuck

    Canuck Active Member

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    Same here and my 2012 Leaf just lost a bar. I only made an exception with my Leaf when it was hot in the summer and the car just arrived home. I allowed the battery to cool off before charging because the Leaf doesn't have a cooling system. Other than that, I always plug it in. With a Tesla you don't need to worry about that since it cools the battery before charging. However, I'm like BertL with my Tesla. If I'm going out again in my Tesla, when I arrive home I don't plug it in. Only at the end of the day with the Tesla but all the time with the Leaf.
     
  12. FlatSix911

    FlatSix911 918 Hybrid

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    ABC and ACMSIAHMS!
     
  13. mwulff

    mwulff Member

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    I used to think a lot about charging. These days I just set the charge limit to 80% (don't need more) and plug in when I get home. The S has enough range that it is never a problem for me.

    Your mileage may vary
     
  14. hpjtv

    hpjtv Member

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    8 years and unlimited mileage warranty on the battery and drivetrain so why worry about it? After 8 years, you'll probably want a battery upgrade or a new car.
     
  15. Canuck

    Canuck Active Member

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    Because after 5 years I would still like to make it to my cabin on one charge. Just because the battery is warranted, doesn't mean it's covered for degredation. Degredation is going to happen. How much is within our control -- at least to a certain extent anyway.
     
  16. bancroftc

    bancroftc Member

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    Excellent post BertL!
     
  17. Petra

    Petra Member

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    Just an FYI: the battery capacity gauge in the Leaf isn't linear. The first bar lost represents about a 15% loss of pack capacity and each additional bar represents about 6.25%. Based on the numbers from LeafSpy, our 2012 Leaf is down about 25% after ~3 years and 20k miles (not quite at 3 bars yet) and the car has never been charged outside in the heat, never been DC fast charged (no CHAdeMO port), only been charged late at night in an insulated garage. That said, it's really hot here in the summer so the car gets to sit out in a parking lot all day and cook. One of the issues I've noticed is that once the battery gets hot, it stays that way for a really long time due to the lack of a cooling system--park it outside on a 110F day, come home, park in garage, and the pack will be in the mid to high 90's five hours later (granted, the garage is usually in the low 80's).

    I'm hopeful that our 70D will fare much better out here... just have to wait until next week to pick it up. :biggrin:
     
  18. GasKilla

    GasKilla No Gas Know Peace

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    I have over 40k miles on my Leaf so I guess I'm lucky to not have more loss, but it's lame how limited the range is for anything other than my daily commute.

    Looks like your 70D is showing up sooner than mine, let me know how big the difference is ...
     
  19. apacheguy

    apacheguy Sig 255, VIN 320

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    I'll save you from doing guess work. Night and day. The Leaf is like something from the stone ages compared to a Tesla. Yes, I also drive a Leaf.
     
  20. juggie

    juggie Member

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    Leaf is build by Japanese and Tesla is build by American manufacturer do I need to explain which is the best in quality?
     

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