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To Range Charge or not to Range Charge?

Discussion in 'Model S: Battery & Charging' started by C.Ford, Feb 18, 2013.

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  1. C.Ford

    C.Ford Member

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    I have a 290 mile round trip I take acouple times a month. Along the route, there are no charging optionswithin 120 miles of my house. The majority of the time, the trip willinclude an overnight stay at the midpoint where there is a 14-50(240V/40A) charger, so no problem making it on the standard charge.Three times, I have range charged for the trip. The first time wasjust to test the range charge. The second time, I took the family tothe circus and we charged at a public station while we ate andshopped before and after. Three hours of charging left me with 181miles of rated range for a 145 mile return trip. The temp had droppedfrom mid 50s to high 30s, though, and I reached home with 20 miles ofrange left. For the third trip, I knew I had about 5 hours to chargeon the 14-50 outlet so the night before I set the charge to standard.Then they called for 1-2 inches of snow and temps in the low 30s atthe time my son and I would be making the return trip. What if Ineeded to cut the charging time short to get ahead of the weather?What if it got colder or snowed more than forecast? What if thereturn trip took longer? What if we there were detours? Gun shy afterthe last trip, that morning I switched to max range charge and weleft once it topped off. I drove normally and kept the climatecontrol temps comfortable. I got a little more than 5 hours of chargein and charged up to standard, the temps stayed in the low 30s, thesnow didn't stick to the roads and we got home with 95 miles of ratedrange left. I didn't need the range charge, but I could have. So,what is the relative risk? How many range charges a month can you dowithout appreciably affecting battery life? Did I mitigate any riskto the battery by leaving as soon as I reached max charge? Is it moreprudent to err on the side of caution over running out of range orprematurely burning out the battery? Any advice is appreciated
     
  2. ElSupreme

    ElSupreme Model S 03182

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    I would range charge when you are doing long-ish trips. As you get more and more comfortable with the car you will feel confident about forgoing the range charge.

    Bottom line range charge whenever you are going to drive more than 180 miles until you are confident you don't need it. And also push the range charge button 1-1.5 hours before you leave, not the night before, and make sure to drive to less than 90% before you make any long stops.
     
  3. stevezzzz

    stevezzzz R;SigS;P85D;SigX

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    From my reading of the forum threads on charging, it seems the following is the consensus of the group to date.

    1. Only charge in Range mode if there's a chance you actually need the range. The flip side: don't be afraid to charge in Range mode if you think you need the range: that's what it's for.
    2. Driving as soon as the Range charge completes is better for the battery than waiting for several hours before departing. Besides, you'll have lost a few miles to vampire loads if you wait.

    You lost me when you wrote: "...I got a little more than 5 hours of chargein and charged up to standard...". I thought you'd used a Range charge? Or was this an intermediate charge stop on the way home? If you knew you were going to have to stop anyway, the only reason to do a Range charge before you left would be if the charger at the departure point was faster than the charger at the en route charge stop: otherwise there's no time benefit to you and probably a penalty, since the charge rate ramps down as your SOC gets up close to 100%.

    Did you mention what battery size you have?
     
  4. RDoc

    RDoc S85D

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    I strongly feel that Tesla should make all this much more transparent. Aside from their battery damage warning, there's no official information that I'm aware of that people could use to evaluate the trade off between range and damage. Why not just tell owners and potential purchasers what the effect of range charging is so they can make their own decisions?
     
  5. montgom626

    montgom626 Active Member

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    Range charge when any doubt exists
     
  6. ElSupreme

    ElSupreme Model S 03182

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    Because you would probably need a degree in chemical engineering (Li-Ion specialty) and Electrical Engineering and a text book to properly outline what will 'damage' the batteries and how much damage you will do. It isn't simple and there are SO many variables!
     
  7. Kevin Sharpe

    Kevin Sharpe Active Member

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    It's extremely complex and not something most lay people would understand. It's important to remember that this is 'just' a car... so follow the simple rules and range charge just before you start your drive :smile:
     
  8. meduri

    meduri Member

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    I agree with you ElSupreme and I'm sure that the Tesla R&D folks got the degrees you were referring to, went through all the text books and created this wonderful product that I love it. All they need to do is to summarize their analysis and share the hypothesis in a language that my mom can understand it.
     
  9. C.Ford

    C.Ford Member

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    I have the 85kw battery.

    I range charged immediately prior to leaving home. Starting with a rated range of 270 miles, I arrived at the midpoint charging destination (parents' house) with 110 rated miles. I estimated needing 210 miles of rated range to make it back home safely (1.5 X 145 miles). I average 25mi range added per hour of charge at my parents' house, which means I would be ready to go after 4 hours. If I had started with a standard charge (and 30 miles less range), I would need to spend an additional hour or so charging. Under normal conditions an hour wouldn't make a difference, but had the weather turned for the worse an additional hour of snow/sleet/ice on the road could have made a difference in road conditions.

    I probably should have driven the Subaru like my wife said, but after driving the S for a month it is so hard to go back to driving anything else.
     
  10. RDoc

    RDoc S85D

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    Hmm, I'm not sure how to reply to a comment like this. Amazingly enough, there actually are people buying Teslas who aren't "lay people". Some of us know how to use modern high speed electronic computers and even have degrees in engineering and careers in cutting edge technology.

    To reply to another comment. Your mom may not understand some aspects of technology, but there actually are women out there with children who not only understand a lot of technology, but personally create it, so perhaps you might want to reconsider that statement.

    There's no reason that Tesla couldn't publish a table or graph that summarized % of battery degradation caused by range charging parameterized by the major factors affecting it, e.g. time spent above 90% charge, remaining capacity, etc. I'm doubtful it's all that complex simply because the battery itself controls the charging rate and its charging environment. The question isn't the general one of what effect charging has on some generic battery, it's specifically what the effect of range charging has on the Tesla battery pack. Anyway, even if many people didn't want to bother understanding it, a lot of others would and it would end the current guessing and speculation. Perhaps it's true that range charging isn't a big deal, but there's no way to tell without more information or experience, and that experience could be pretty costly.

    I thought that the general notion that consumers shouldn't be told what they are buying because they are so benighted that it might confuse them was thoroughly discredited by now.
     
  11. ElSupreme

    ElSupreme Model S 03182

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    I am saying that a 'summary' would require a book, and high level math, chemistry, and electrical understanding. Just putting together a set of graphs with C rates, temperature, and SoC you are probably looking at hundreds of pages worth of graphs.

    And variability between cells, and any sort of internal Tesla Voodoo magic would all get missed and might be a larger part of degradation. I don't think there is a simple way to guage degradation past what they have provided.

    Always plug in. (High SoC is better in general)
    Only Range charge if you need it. (Very high SoC is to be avoided)

    - - - Updated - - -

    Have you ever had a car manufacturer tell you how much a cold engine will lower the life of the car? How about a hot engine? How about a light bulb manufacturer telling you how much on/off cycles affect the life of the bulb? All of these things lower the life of the object but you don't get any data on that, not even automotive engineers.

    There are two reasons. There are so many variables you can't really tell people past 'driving with a cold engine isn't good for it'. Same for turning fluorescent tubes on and off.

    And if you do actually produce detailed numbers customers screw you on them. Broder blamed Tesla because his miles were greater than his trip. If Tesla just had a 78% on the dash he couldn't have screwed them over! And something as complex as degradation you are going to get people holding you to those numbers. You just can't publish them.
     
  12. Doug_G

    Doug_G Lead Moderator

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    Tip: The App is very handy for this. If you're leaving in the morning, switch it to Range mode as soon as you wake up. Leave as soon as it's finished. That way you minimize the time at full charge, with virtually no extra long-term degradation.
     
  13. RDoc

    RDoc S85D

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    Why do you think that? The car completely controls the rate of charge and it's internal environment. As far as any "high level math, chemistry, and electrical understanding", what would that be? There's no issue of various C rates, temperature and SOC. The car controls the first two, and I'm very doubtful that there's a significant difference due to charging above 90% SOC between going from 30% to 100% than 60% to 100%, they both go through the normal 90% SOC when the transition from normal to range charge occurs.

    The battery and its management can be considered a black box. There's no need to know what's going on inside and that's likely proprietary anyway. What customers should know, and shouldn't be proprietary, is how the battery responds to range charging. Clearly it's significant enough that they issued a warning about it.

    My NSX manual warns that the engine should always be up to operating temperature before anything beyond moderate use. It's not OK to sometimes do full power runs with a cold engine, it's never a good idea. However, the reality is that the reason there isn't a quantitative value on that is because it's a trivial effect, the decrease in a car engine's life due to cold starting (within reason) is miniscule. As far as overheating an engine, I've never seen any car manufacturer say it was OK to drive an overheating car at all, whether "needed" or not, the instructions are to immediately stop and have the car serviced. I actually went to school with automotive engineering students and I can assure you that they studied the effects of ambient temperature on engines. This isn't mumbo jumbo, it's engineering.

    Here's a link to a Philips site giving the number of on/off cycles their CFL's are rated for: http://7myths.planetark.org/ Some companies really do publish information about their products, why not Tesla?

    This is the ultimate argument I have a big problem with. While I certainly hope Tesla succeeds, if for no other reason that I want to enjoy my X for a long time, I disagree that it's OK to leave customers in the dark to benefit Tesla or any company. They've already gotten themselves into trouble with inaccurate range readouts, but I don't think the correct response is to simply remove all real time range estimates which is what you seem to be advocating.

    This is the same argument used when food ingredient labels were first required and is being used now to argue against fracking regulation. Tesla seems to have no problem advertising 300 miles of range, but there are a lot of circumstances when that's not even close to possible to achieve. If range charging degrades the battery, but it's still OK to use it sometimes, I think they should say what the trade off is. The notion that it's too complex for some people to understand, therefore it should be kept secret seems a bit bizarre to me.
     
  14. napabill

    napabill Active Member

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    Another vote for the App to include a function allowing you to put in departure time and let the "S" figure out how best to charge to get there.

    Also, not clear on whether charging longer at a lower amperage vs shorter at the max amperage has any effect on battery degradation. Of course, the above mentioned App would factor that in correctly.
     
  15. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    I don't know that it's kept secret, but a lot of folks just don't want to be bothered with any details. An example is that Denise won't delete the spam in her inbox because it's too much trouble (of course she also complains that she can't find the non-spam mail). There are a lot of people like that and if you give them more than two short sentences to read they just won't buy your product.
     
  16. aronth5

    aronth5 Long Time Follower

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    +1 and add distance along with departure time
     
  17. ElSupreme

    ElSupreme Model S 03182

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    No the car does not 'completely control its internal enviroment' It has started charging immediately when plugged in every time I have tried. I have driven on 75 degree day, and a 35 and raining day. I doubt the battery pack was the same temperature, it wasn't the same SoC, and I charged at different C rates? All of these are variables, granted Tesla can control the variables but they don't as long as they are in a range.

    I no driving changes the C rates all over the map from 320kW to -60kW. It certainly isn't controlled. The current SoC certainly has effects on charging. That is why Tesla changes the power limits at low battery levels, and limits charging and regen at high SoC. It has effects on the battery doing the same exact things at different SoC.

    But that is EXACTLY what you are asking for. The battery degradation happen INSIDE your black box.


    I never said it is mumbo jumbo I said Voodoo. I am an enigneer. I deal with fluid flow ALL THE TIME. And guess what. I can give you a fluid problem that you can write an equation for. And guess what. It is an UNSOLVABLE equation. You are asking Tesla to accurately predict weather, and doing it on a different planet for each car. Sure all the rules are the same, and the planets look alike but predicting the weather is hard. Predicting the weather on my planet and your planet is damn near impossible.

    Exactly my point your NSX says no hard stuff with the engine cooled because you might damage it. Exactly what Tesla is saynig. There is no quantified value, or estimate about how hard you can drive on a cold engine. As for hot I didn't say overheating. What if it is 100F outside, your car will probably run a degree or two hot. Are you saying it won't cause more/less wear when doing that. How much? You want Tesla to give you a quantitative 'how much' when nothing like that happens ANYWHERE!

    It does give the number of cycles the CFLs are rated for. Tesla gives you the number of miles the battery is rated for 100k, 125k, unlimited. The battery is also limited to 8 years. Philips tells you nothing about expecting 3 minutes less life for every cycle on/off.

    That is exactly my point. They are already giving out WAY more information than anyone else. I don't think they should/would change to a percent methoud. But they are paying for giving such detailed information. Why give out stuff that is so complex, and not fully studied (some batteries are better than others even off of the same manufacturing line).

    Exactly I could drive the S out of charge in 100 miles. Dave Metcalf drove over 400. And distance is WAY easier to calculate than battery degradation. There is NOW way to convey that to even technically apt public. I doubt Tesla can even say what sort of degradation 100 range charges would due, and I bet it would do different amounts of degradation to different battery packs. They just know that range charges are harder on the pack than standard charges. It isn't that they should be kept secret it is that they can't tell anyone without certainty.
     
  18. adelman

    adelman R 539, S VIN S44, X Sig#1

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    Talking with engineering about this same issue on the Roadster battery... I would assume the same advise is valid on Model S.

    1) It is better for the battery if you use the "top" rather than the "bottom". In other words, it is better to range charge and use the top 10% of your battery than to not range charge and run it below 10% SOC. [This is because heat is the enemy of a LiIon battery. When the SOC gets low, the internal resistance goes up and more heat is produced during discharge.]

    2) It isn't range charging per-se that damages the battery, but elapsed time spent above the normal charge. If you do range charge, plan for it to complete immediately before you leave on a drive that uses the extra charge.
     
  19. aviators99

    aviators99 Model S - R140

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    Apparently, this doesn't work anymore, as of 1.19.42. You have to physically unplug the car and plug it back in. There's a discussion of this on the REST API thread under user interface.
     
  20. stevezzzz

    stevezzzz R;SigS;P85D;SigX

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    That doesn't seem right to me. I'm on 4.2 and just this morning tested this feature. My S had been parked overnight in a cold garage, plugged in, with a Standard charge which completed about 10pm last evening. This morning around 10:30a I used the app to switch from Standard to Range charging: the app reported it ramped up to 40a (I've got a 14-50) at 240V and told me it would be finished in an hour and change. Then I used the app to switch it back to Standard charging and, since the SOC had sagged overnight to a Rated 234, it remained charging at 40a/240V and told me it would be finished in 10 minutes. Then I stopped charging, since I was just testing the app.
     

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