TMC is an independent, primarily volunteer organization that relies on ad revenue to cover its operating costs. Please consider whitelisting TMC on your ad blocker or making a Paypal contribution here: paypal.me/SupportTMC

Putting some numbers on the factors that affect range

Discussion in 'Model S: Battery & Charging' started by ChadS, Jan 27, 2013.

  1. ChadS

    ChadS Petroleum is for sissies

    Joined:
    Jul 16, 2009
    Messages:
    2,401
    #1 ChadS, Jan 27, 2013
    Last edited: Apr 23, 2014

    First, a note for EV newcomers


    The math below is just geeky fun. It is NOT an essential part of owning a plug-in vehicle; if you find it boring, ignore it. Driving electric really is simple. Here’s all you need to know to start using a plug-in without ever doing any range calculations or having to worry about hypermiling:

    1. Buy a plug-in hybrid, like the Chevy Volt, Ford Fusion or C-Max, Fisker Karma, etc. They are still gas cars, so they drive just like a gas car on a trip. No thinking ever required.

    - OR -

    2. If you want to use even less gas, do less maintenance and save more money on a full battery-electric, look at the EPA range rating (not the higher marketing number. For example, Nissan often says the Leaf can go 100 miles. Tesla sometimes says the Model S can go over 300 miles. But the EPA ratings are 73 and 265). Now, subtract my magic-rule-of-thumb 1/3 to account for really bad weather or really high speeds (presumably you won’t do both at the same time). That leaves 49 miles for the Leaf, and 177 miles for the 85kWh Model S.

    Those are numbers you can “count on” in your new car. Obviously you can do worse if you take it to the track or something, but as long as you aren’t trying to fail and really want to get somewhere, you will be able to go at least that far - and much farther once you get used to it. You can take the car on any trip of that length without worrying or doing math; so just make sure your next Model S charging stop is never more than 177 miles away. Math is only required if you want to go farther than that without stopping to charge.

    After several (5-10) years the battery will lose some capacity, so we need to account for that too. Of course by then you’ll have lots more experience and will be comfortable taking the car on longer trips; but if you have a long commute and want to make sure the car you buy will ALWAYS work for you without ANY planning or charging, then take 70% of the number above. That puts the Leaf down to 34 miles, and the 85kWh Model S down to 124 miles. If you have to drive farther than that, don’t have another car for those long trips, don't want to rent, won’t ever be able to charge, and don’t want to buy a new battery, then you will be more interested in a plug-in hybrid.


    Let the math begin

    OK, now that we are only left with people that WANT to go through the math, here are some numbers for calculating how far you can get in your Model S. The more you understand the car, the farther (and more often) you can take it rather than your old gas car that you really don’t want to drive anymore.

    Spoiler: you can skip all the math if you always plan charging stops within 2/3 of the EPA range of your car - unless you're racing up a mountain, you will make it (although it's always wise to plan an extra 20 mile buffer or so, just in case the charger is unusable!). For the 85kWh car, that's 177 miles. For 60kWh it's 139 miles, and for 40kWh it's 95.

    The math is not complicated - it's just adding percentages together to see how it compares to rated range. At 100%, you should by definition expect the rated range and a 200-mile trip should be easy, leaving you with 65 miles left over. But if you add in, say extra speed and cold weather to get 133% of rated miles, that means your 200-mile trip will take 266 miles of rated miles - and you will likely not make it. Plan a charging stop.

    When planning a trip in advance, I don't know what the weather is going to be and so I plan for the worst and never have charging points be more than 177 miles apart - the longest drive with no charging in my Death Valley trip was 175 miles, and even there I had a plan for a place to charge in the middle if things went bad. You can make assumptions and plan it closer than this, but in my experience that just adds stress. On the day of the trip, I know a lot more about conditions and so I can make adjustments - sometimes, for example, I take off from a charging stop before charging all the way because I know the buffer is much larger than it needs to be. Or sometimes I drive faster just because I know I have the extra range.


    Range number origins


    The Model S 85kWh is rated by the EPA to go 265 miles per charge. That rating comes from a complex test that includes city driving, speeding up and slowing down, etc. But when calculating range, most people are concerned about steady driving on the freeway. From Tesla’s numbers, 265 is roughly what you’d expect going 60mph on dry level ground with 19” wheels and a small amount of HVAC use (outside temps of, say, 55 or 90). 300 miles is what you’d expect going 55mph on dry level ground at 70 degrees with no HVAC.

    The EPA number is a good number to use to compare vehicles. But it’s not a good number to use to tell how far you’re going to go on any specific trip. That’s why I wish EV battery indicators simply gave the % of the battery left, rather than a number of miles which is just the battery % multiplied by some factor that they don’t explain clearly and may not apply. It is true that new owners will find it confusing; but after a few weeks of using the car, it is much better information. New 85kWh Model S owners could simply be told to figure they’ll usually get 2 miles or so per percent of battery; perhaps up to 3 miles if they drive carefully in ideal conditions.

    All of the numbers I'm going to use below assume you are taking a long trip. When you take short trips, initial HVAC load may be a much higher percentage. However, that is often balanced out by much lower speeds as well as the far greater unlikelihood of putting on more than 177 miles in the day. Short trips in a long-range car generally don't need calculations (people with short-range BEVs do these calculations more often; but it's not a big deal for them once they are used to the car because with short-range cars you typically make the same trips over and over, so you soon "know" if you can make it or not and can skip the calculations). Note that around-town consumption is often lower in BEVs because of the much lower speeds; but may well be higher in the Model S because of the much greater than average weight that needs to be accelerated from every stop, plus the awful temptation to take advantage of all the available acceleration.


    Range calculators


    Tesla’s range calculator is attractive and easy to use. It seems to be pretty accurate. It says that if you go 65mph on level dry ground with HVAC on at 32 degrees, you will get 218 miles. That’s using 118% of rated miles to go 5mph faster and use more HVAC. But what if you go even faster than 65? What if it’s colder than 32 degrees? What if there is rain or snow on the ground? What about elevation changes? I asked Tesla to add these items to their calculator long ago, but no word on when or if they will.

    HERE is another calculator that takes elevation in to account, and allows a wider range of speeds to be entered. But it doesn’t account for weather or road conditions at all.

    Somewhere on these forums I saw mention of yet another calculator that sounds interesting, but it is Mac-only and I don’t have a Mac so I have not been able to try it. (EFusco found it for me: it's HERE).

    Update Mar 2013: a Model S owner (Cliff Hannel on these forums) has been building his own version HERE. Forum thread HERE. It is not finished yet, but it appears to consider all of the relevant factors (speed, temperature, elevation, etc) except road conditions. This would be a great web page to have saved in your car's web browser.


    Real-world experience


    Tesla's consumption documentation and the calculators were a great place to start. But I had to extrapolate some of the numbers, and add in some real-world EV experience for things they did not address. In addition to a Prius I turned in to a PHEV in 2008, and a Toyota RAV4-EV I bought in 2009, and a Tesla Roadster I bought in 2009, my wife and I have been keeping track of numbers on our Model S that we received in September. We now have 7,000 miles on the car, and recently returned from a 3,000 mile trip.

    Do not take these numbers as gospel! They seem to work pretty well for me, but I have done a lot of strange and varied things to get them. Several of them are really just guesses. I look forward to hearing from people that have thoughts on refining the numbers. Try 'em out and see if they work for you.

    Numbers from our trip are below, but first here are some factors that I consider when estimating range.


    Speed


    This is the largest factor that you have control of. (Acceleration could be a far greater factor if you did it a lot; but it is typically of very short duration on a road trip). If you are ever in trouble, slow down. But if you plan, hopefully you will never be in trouble as your next charging point will always be easily in range.

    I sometimes slow down to be more efficient; especially if my next charging stop is a slow one - going slower can reduce your wait at the next charging station. But I always plan my charging stops to be close enough that I never have to slow down to make sure I will make it. Worries about "having to drive a BEV slow" and "sweating bullets about making the next charging point" are overblown - don't push the limits, and it will never be a problem.

    45mph-26%
    55-8%
    60100% of rated range (at 70 degrees with miniscule HVAC)
    65+8%
    75+26%


    Temperature


    Model S Range.jpg

    At full blast, HVAC pulls about 7.5kW. What % hit that is depends on how fast you are going. And of course you will not usually have it on full blast. AC takes less than heat (at 90 degrees Tesla says the range is the same as 70; Model S batteries must like it a little warmer than Roadster batteries). But at 60 – 75mph freeway speeds, 30% would probably be the upper end. It appears about 1/3 of this hit happens even with HVAC off, so that’s the portion to manage the batteries. Because the HVAC draw is time-based rather than mile-based, these percentages should be slightly higher for lower speeds and slightly lower for higher speeds, but I haven’t taken the time to do the adjustments here.

    If you ever get in trouble (again, plan for the worst case and you shouldn't) and the weather is extreme, you can turn the HVAC off and that can save quite a bit. It can be very unpleasant however, especially if you have a spouse grumbling about it the whole time. Also note that you only save 2/3 of the numbers below by doing that, as the car will keep conditioning the batteries.

    A couple of times (when my wife is not with me) I have turned down the heat to be more efficient; especially if my next charging stop is a slow one - using less heat can reduce your wait at the next charging station. But I always plan my charging stops to be close enough that I never have to turn off the heater just to make sure I will make it. Worries about "being unable to use heat" and "sweating bullets about making the next charging point" are overblown.

    15 degrees F+25%
    32+13%
    50+7%
    70100% of rated range (HVAC on, but barely in use)
    100+7%
    120+13%

    Update: Fleetcarma.com just released some data on how temperature affects the Leaf's range. Of course it's a different chemistry with no thermal management on the pack, so the numbers will be different, but it is still interesting. It too gets near-max range in 70 - 90 degree weather. 32 degrees seems to take off about 20%, and 15 degrees takes off about 30%. Those are bigger hits than on the Model S, but this was measured on the older Leaf that uses a resistive heater; the 2013 will have a heat pump. At -13 it took off about 40% (the cabin heater, which is not terribly strong, probably maxed out at around 15-20 degrees; but the pack heater kicks in at 14 degrees so greater draw continues). 100 degrees only seems to take off a percentage or two, but you can see the curve is getting sharper around there.


    Elevation


    Other EVs (Roadsters and RAV4-EV's) use 7 miles up and 4 miles down; but the Model S is heavier. Subtract 10 miles for every 1000’ of elevation gain. Add 6 miles for every 1000’ of elevation loss. There’s probably no getting around the numbers for elevation gain, but there could easily be variation in the numbers for elevation loss – it depends on how fast you are going, how gradual the loss is, how much regen and wind resistance affect your speed, etc. Gain and loss numbers could both be larger if you carry more weight in your car.

    Note that these are the number of miles to add or subtract, so you have to divide by the length of the trip to get a percentage. Ideally you should count ALL of the ups and downs on the trips; although I generally just look at the net elevation change, and any major passes along the way.


    Road conditions


    Stuff on the road (could be sand, rocks, garbage, varying pavement quality, or what have you; but most often rain and snow) obviously slows the car down – just FEEL how your car slows down when you’re coasting on the freeway and hit a puddle. I know from experience that stuff on the road makes a difference, but these numbers are really just guesses. They do seem to roughly fit the data, though.

    Clear and dry100% of rated range
    Wet roadway+2%
    Standing water+10%
    Light snow+15%
    Heavy snow+25%


    Cold-soak recovery


    This is very speculative*. But a few people that have driven their cars to low levels in dropping temperatures have gotten warnings that the number of miles remaining may suddenly drop. And many people have reported that if you leave the car sit overnight without being plugged in, a lot of miles (say, 10 - 30) may disappear. A couple of people have further noticed that if you get in that cold car that has lost miles and drive it, some of the miles seem to “come back” - they use fewer rated miles than expected to get to their destination.

    It is possible that to protect the batteries, in colder weather the car may hide a certain percentage of the battery’s remaining energy, or of its total energy capacity. (It is also possible that it lists a lower number of miles assuming lower efficiency or more pack warming; but I think that less likely and doesn’t fit anecdotal reports quite as well). As the car warms up, some of the hidden energy may reappear. But how much, and at what temperatures? I don’t have nearly enough data to say with any certainty; this only happened to me a couple of times on this trip. But a 49-mile trip after a cold soak ended up doing about 4 miles better than expected as temps rose from 29 to 33 (that trip started at 173 rated miles, after losing 10-15 from the night before). A 70-mile trip after a cold soak did about 18 miles better than expected as temps rose from 30 to 42 (starting at 126 rated miles after losing 24 from the night before).

    Fortunately it looks like the recovery roughly counteracts any phantom losses during the night; if so this may not be a measurable factor (except when you do your math based on the lower cold-morning numbers; but in that case it improves your numbers, so no harm done).

    *UPDATE: This is a little less speculative now. Consumer Reports ran in to this (losing 30 miles overnight), and Tesla confirmed that the car "readjusts" range in freezing weather, and that it will sneak back as the car warms up. They didn't give exact amounts or say at what temps; but for simplicity's sake (and because it matches my data and what I've heard from others) I will guess the car really only loses 4 miles overnight in cold weather. If you check in the morning and it's below freezing, you will appear to have lost an additional 10 - 20 miles perhaps depending on the temperature delta. Those miles will, I assume, all come back if you get well over freezing; but you might only get, say, half of them back if you're still close to freezing. I'm not really confident in those numbers, but they fit the data we have so far.


    Wind


    Wind can affect you just as much as speed; it’s wind resistance that causes the drag. However it can help as much as hinder, is difficult to measure from inside the car, usually is not strong enough to be a large factor, and even when it is strong it typically doesn’t last the whole trip. So I haven’t accounted for wind here; but it’s entirely possible that it is responsible for a large bit of the differences between my expected and actual energy use. Wind has never caused me to run out of power in an EV, but the only time I ever ran out of gas in an ICE was because of a serious headwind in South Dakota that affected my mpg much more than I expected (I think I normally got 30-35mpg, but got just over 20mpg on that trip and fell short of the city I was planning to buy gas in).


    Miscellaneous


    Random other factors that can affect performance.

    An early version of the calculator gave a much smaller loss (roughly 2.5%) due to the 21” wheels. I am not sure why the number is so much larger now.

    Headlights and other 12V loads are minuscule. I don’t bother to calculate them at all.

    21" wheels instead of 19" wheels+6%
    Attaching pizza pans to your wheels-6.5%
    Rolling down the windows+4%
    Turning on headlights+0.25%


    Applying it all to a real trip

    Here are numbers from our 3,000 mile trip from Seattle to Death Valley in mid-Jan 2013. The first important number is 0; that's how much I spent on fuel for this trip. All of the chargers are free.

    Our car in Death Valley:

    IMG_5486 - Copy.JPG

    This was not my first EV road trip; I've taken the Roadster on several long trips. My first trip, almost 3 years ago, was from Seattle to San Diego at a time when there were NO charging stations of any type North of San Francisco, and only a few L2 stations South of there. I was really excited to take the Model S as it is much larger, quieter, smoother, can use Superchargers when available, allows HVAC while charging, etc. Yet there is still room for improvement; for example, it still doesn't notify you when charging stops. That is a serious pain when you are charging at an L2 station for hours as you have to keep checking it to make sure a breaker didn't trip, or risk a several-hour delay to your journey (that has happened to me more than once, and is why I added OVMS to my Roadster).

    Before the numbers, a mess of caveats:

    • I did not account for wind
    • I did not adjust HVAC consumption for speed
    • We weren't exceptionally careful on writing down all the numbers exactly when we left and arrived
    • We did not account for occasional heavy acceleration
    • We did not even try to get precise measurements of water on the road, exactly how much time was spent at varying temperatures and speeds, etc
    • I counted net elevation changes and major passes, but did not figure other hills
    • I just added the percentages of the various factors to make the math easy. Their interaction is usually more complex; but my method probably overstates the hit, and so is safer.
    • The car's Wh/mi readings did not seem to correlate well with the number of rated miles used. I find this surprising, and may start another thread to discuss that. For now I have those numbers grayed in the table so we can ignore them and just focus on the rated mile numbers, which are easier for most people to understand anyway.
    Given all that sloppiness, I am pleased that the rated miles I consumed on each leg ended up within 6% of the miles I estimated. Though you should note that I did not pick the "road condition" or "cold-soak recovery" numbers until AFTER seeing all the other numbers, so by definition my guesses fit the data here, but I have no other reason to believe they are correct. (Road conditions only mattered for the first few legs; for most of the trip the roads were clear and dry. Cold-soak recovery only happened on the two legs after a night without charging).

    No matter how much time you spend calculating, any number of things can still go wrong. You could hit very high winds, you could do the math wrong, the charging station could be blocked or broken...always leave as much buffer as you can. That's why Superchargers are 120 miles apart instead of 250 miles. You should do that with your charging stops too. It's less stressful, more pleasant, easier on the battery, and gives you options when bad things happen. If your charging stops are close enough together, you never have to do any math!

    Trip legActual DistanceTemperatureElevation changeRoad conditionSpeed% of rated miles expected to use% of rated miles actually usedRated miles usedWh/mi
    Redmond WA 50’ to Centralia WA 200’93 miles37 - 43 F
    +10%
    150' gain
    +1%
    heavy rain
    +10%
    63 - 70
    +12%
    133% of rated139% of rated129 miles
    Centralia WA 200’ to Tigard OR 200’10040
    +10%
    nonelessening rain;
    +6%
    70 w/traffic
    +16%
    132%137%137
    Tigard OR 200’ to Eugene OR 500’10639 - 41
    +10%
    300' gain
    +2%
    Damp; sprinkles
    +2%
    66
    +9%
    123%123%130
    Eugene OR 500’ to Canyonville OR 800’9132 - 36
    +12%
    300' gain
    +2%
    Some rain/snow
    +10%
    60 - 66
    +6%
    130%138%126
    Canyonville 800’ OR to Yreka CA 2800’12427 - 34
    +13%
    3200' gain
    1200' loss
    +16%
    Water, snow
    +12%
    40 - 65141%145%180
    Yreka CA 2800’ to Orland CA 300’15527 - 54
    +10%
    1200' gain
    3700' loss
    -4%
    Mostly dry55 - 70
    +4%
    110%104%161
    Orland CA 300’ to Davis CA 300’9439 - 48
    +10%
    nonedry70
    +17%
    127%122%115
    Davis CA 300’ to Palo Alto CA 150’10948
    +8%
    150' lossdry65 with traffic
    +8%
    116%121%132
    Palo Alto CA 150’ to Gilroy CA 300’4929 - 33
    +13%
    -8% cold soak
    150' gain
    +2%
    dry67
    +12%
    119%118%58 (really 62 after cold soak)
    Gilroy CA 300’ to Coalinga CA 450’11338 - 48
    +10%
    1000' gain
    850' loss
    +3%
    dry55 - 74
    +8%
    121%126%142
    Coalinga CA 450’ to Lebec CA 1100’11638 - 52
    +8% temp
    650' gain
    +4%
    dry75
    +26%
    138%131%152
    Lebec CA 1100’ to Barstow CA 2400’15237 - 52
    +10%
    1900' gain
    600' loss
    +7%
    dry55 - 70
    +6%
    123%124%188
    Barstow CA 2400’ to Furnace Creek CA -200’17525 - 47
    +12%
    1696 loss
    1624 gain
    700 loss
    1709 gain
    3234 loss
    dry55 - 70
    +8%
    120% (no net elevation effect!)126%220
    Furnace Creek CA -200’ to Barstow CA 2400’17552 - 64; little HVAC
    +3%
    (reverse above)
    +15%
    dry55 - 70
    +6%
    124%121%212
    Barstow CA 2400’ to Mojave CA 2800’72 (with detour)49 - 59; HVAC off
    +5%
    400' gain
    +4%
    dry55 - 70 (more 70)
    +10%
    119%125%90
    Mojave CA 2800’ to Lebec CA 1100’7030 - 42
    +10%
    -29% cold soak
    200' gain
    1900' loss
    -9%
    dry55 - 6572%74%52 (really 72 after cold-soak)
    Lebec CA 1100’ to Coalinga CA 450’11644 - 59
    +6%
    650' loss
    -2%
    dry70 - 80
    +26%
    130%129%150
    Coalinga CA 450’ to Gilroy CA 300’11260 - 68
    +3%
    850' gain
    1000 loss
    +2%
    dry55 - 85
    +17%
    122%123%138
    Gilroy CA 300’ to Davis CA 300’13155 - 68
    +4%
    nonedry55 - 75
    +8%
    112%114%149
    Davis CA 300’ to Orland CA 300’9435 - 41
    +11%
    nonedry70
    +17%
    128%134%126
    Orland CA 300’ to Yreka CA 2800’15545 - 70; little HVAC
    +3%
    3700' gain
    1200' loss
    +14%
    dry65 - 70
    +12%
    129%129%200
    Yreka CA 2800’ to Canyonville OR 800’12432 - 45
    +11%
    1200' gain
    3200' loss
    -4%
    dry60 - 70
    +8%
    115%115%143
    Canyonville OR 800’ to Eugene OR 500’9128 - 30
    +15%
    300' loss
    -1%
    dry68
    +13%
    127%127%116
    Eugene OR 500’ to Tigard OR 200’10629 - 37
    +12%
    300' loss
    -1%
    dry60 - 68
    +10%
    121%117%124
    Tigard OR 200’ to Centralia WA 200’10036 - 41
    +10%
    nonedry55 but mostly 74
    +22%
    132%128%128
    Centralia WA 200’ to Redmond WA 50’9334 - 36
    +11%
    150' lossdry64 - 74
    +15%
    126%122%113
    Our Roadster in Yosemite:

    339166_10150360366450053_777983794_o.jpg
     
    • Like x 3
    • Informative x 1
    • Love x 1
  2. bonnie

    bonnie Oil is for sissies.

    Joined:
    Feb 6, 2011
    Messages:
    14,241
    Location:
    Columbia River Gorge
    Wow, Chad. That's a LOT of great information in one post. Going to bookmark this and come back to it.

    Thank you!
     
  3. AnOutsider

    AnOutsider S532 # XS27

    Joined:
    Apr 3, 2009
    Messages:
    11,923
    I think those paragraphs needs emphasizing. It should be on a placard sold with every EV.
     
  4. jhs_7645

    jhs_7645 VIN: #3305

    Joined:
    Jul 1, 2012
    Messages:
    451
    Location:
    Camas, WA
    #4 jhs_7645, Jan 28, 2013
    Last edited: Jan 28, 2013
  5. TurboFroggy

    TurboFroggy Member

    Joined:
    Dec 5, 2012
    Messages:
    287
    Location:
    Everett, WA
    Great info Chad! Can you elaborate on charging during this trip? What kind of connection, adapter, amps, what voltage you encountered and how long you charged?
     
  6. efusco

    efusco Moderator - Model S & X forums

    Joined:
    Mar 29, 2009
    Messages:
    4,593
    Location:
    Nixa, Missouri, United States
    If you're a mac user this app is also excellent for doing these calculations for you:
    Main
     
  7. andrewket

    andrewket 2014 S P85DL, 2016 X P90DL (soon 100)

    Joined:
    Dec 20, 2012
    Messages:
    5,047
    The 6% penalty for the 21"'s is why I wish Tesla offered a performance tire on a 19" wheel option, and didn't bundle the 21" with the P85. I would have been more than happy with 19" performance tires, especially if it saved a little $.
     
  8. SCW-Greg

    SCW-Greg Active Member

    Joined:
    Jun 13, 2012
    Messages:
    1,703
    Location:
    Beaverton, OR
    Chad, what can I say?! You're efforts here are epic, truly pioneering for us all. Thank you!
     
  9. tomanik

    tomanik Member

    Joined:
    May 30, 2009
    Messages:
    272
    Location:
    Canada
    Wow, fantastic post. Maybe someday the navigation system will incorporate these type of metrics to more accurately estimate range for trips.
     
  10. ChadS

    ChadS Petroleum is for sissies

    Joined:
    Jul 16, 2009
    Messages:
    2,401
    #10 ChadS, Jan 28, 2013
    Last edited: Jan 31, 2013
    I agree. Believing an EV can really go X miles (where X is a huge number that the marketing department likes) has created quite a few angry customers. They key to enjoying any car is in having it match your expectations.

    Plug In America has tried to get automakers to give out reasonable numbers, but you can imagine how well that has gone over. (Nissan did put out a nice chart that gave estimates for a variety of conditions, but that seems to have been quickly lost and everybody just associates "100 miles" with a Leaf, which is completely unreasonable).

    When I get time, I hope to create another post about that end of things. I did keep data on that too.

    Thanks! I added it to my list of range calculators in the original post.

    That's definitely the holy grail. You type in your destination, and it incorporates all of these factors (well, the ones it can - it won't know how fast you'll drive, for instance) and tells you the likelihood of making it and how much buffer you'll have. Perhaps it could even suggest a speed. We have the technology to make this happen...I hope this sort of analysis will help lead to that sort of tool!
     
  11. giants2001

    giants2001 Member

    Joined:
    Dec 13, 2012
    Messages:
    70
    Location:
    san jose
    Can 60kWh Battery Make Chad's Trip?

    First - Chad I hope you don't mind me playing around with some of your numbers. That was a fantastic writeup. What a fun road trip. :cool:

    I am a complete newbie when it comes to BEVs. The Model S is my first BEV, heck, its my first car that cost more than 10K. I have never been much of a car person until I came across Tesla. First with the roadster, and then this. I placed my deposit almost 2 years ago and ultimately decided to order the 60kWh battery size because of affordability. I know that some might think, if you are going to spend this much money on car, why not spend the extra 10K to get the bigger battery. Well then I should get the performance, right? You see where I'm going with this. I knew the 60kWh would cover more than 95% of any drive I ever plan to take and I had to draw the line somewhere. ... but back to the topic at hand.

    I decided to take Chad's road trip numbers and compare his expected vs. actual to get a better idea of how close his original estimates were. I also wanted to see if my 60kWh could make the same trip. I am leaving out all the variables including charging time, and really just looking at it from a numbers point of view.

    The Take Away:
    1. You can see Chad really did his homework. Worst case was a -8% deviation from the expected vs actual rated miles to use. His numbers were exact on more than one occasion. Very impressive. If I do any long trips, I must take a couple hours to plan it out.
    2. Only 2 legs of the trip seem to be out of reach of the 60kWh battery size. and just barely.
    3. You are almost always going to drive over 60mph and therefore the Rated miles are always going to be greater than the Actual Distance. Another reason to always give yourself a buffer.
    4. No regrets on the 60kWh battery. The car is fantastic and should be sufficient for 99% of any trip I ever plan to take :biggrin:

    % of rated miles expected to use% of rated miles actually usedChad's Calculation DeviationActual DistanceRated miles usedRated Expected to useCan 60kWh Battery Make it ?
    133%139%-6%93129123.69yes
    132%137%-5%100137132yes
    123%123%0%106130130.38yes
    130%138%-8%91126118.3yes
    141%145%-4%124180174.84yes (max charge recommended)
    110%104%6%155161170.5yes
    127%122%5%94115119.38yes
    116%121%-5%109132126.44yes
    127%118%9%495862.23yes
    121%126%-5%113142136.73yes
    138%131%7%116152160.08yes
    123%124%-1%152188186.96yes (max charge required)
    120%126%-6%175220210Maybe (max charge required)
    124%121%3%175212217Maybe (max charge required)
    119%125%-6%729085.68yes
    101%74% Lost 24 miles the night before; 705270.7yes
    warmed up a lot during operation
    27%
    130%129%1%116150150.8yes
    122%123%-1%112138136.64yes
    112%114%-2%131149146.72yes
    128%134%-6%94126120.32yes
    129%129%0%155200199.95yes (max charge required)
    115%115%0%124143142.6yes
    127%127%0%91116115.57yes
    121%117%4%106124128.26yes
    132%128%4%100128132yes
    126%122%4%93113117.18yes
     
  12. kimbapooch

    kimbapooch Member

    Joined:
    Jun 24, 2012
    Messages:
    7
    Location:
    Seattle, WA
    Another data point

    Thanks Chad, I just completed the first leg of essentially the same route down I-5 from Seattle (I'm recharging myself and the Model S at the Motel 6 near Oakland, OR). It's nice to see some real data on how the mountains south of Canyonville will affect my range tomorrow as I head into CA.

    My car has an 85KWh pack, 19" wheels and a single charger. The road was wet and it was about 42 degrees F the whole way. By using very little heat and setting the cruise control to 50mph (VERY painful to do so) I managed to achieve an average of nearly EXACTLY the rated range of 265 mile (295Wh/mi) over the 344 miles I traveled today.

    My takeaway for the day was how very badly we need superchargers in the Pacific Northwest. Give yourself LOTS of time for a cross country trip until we get them. It's painful to watch how long it takes to add back precious miles to that battery pack. I'm getting about 20 mi/hr at the L2 J-1772 stations and 26 mi/hr (due to the single charger) on the HPC at Tesla Service in Tigard (Thanks Jason!). A little less than I was expecting, probably due in part to the cold temp.

    Looking forward to day two and crossing those mountain passes.
     
  13. mnx

    mnx 2013 P85

    Joined:
    May 6, 2009
    Messages:
    2,281
    Location:
    Ancaster, Canada
    I believe the consensus is that the bulk of range advantage the 19's have is the all in the tire/tire compound. If you put a sticky set of performance tires on the 19's any range advantage would evaporate.
     
  14. ChadS

    ChadS Petroleum is for sissies

    Joined:
    Jul 16, 2009
    Messages:
    2,401
    #14 ChadS, Jan 29, 2013
    Last edited: Jan 29, 2013
    Not at all; in fact I'm glad you did - I kind of wanted to address 60kWh cars but just didn't have the patience to keep running numbers.

    It sounds like you are fully aware of this, but I want to highlight it again for anybody else out there either thinking about which pack to buy, or what trip to take their car on:

    Remember that the numbers I presented above all measured the conditions I actually encountered - which were cold, but other than the first few legs were always dry. For planning purposes before the trip, I assumed very heavy cold rain everywhere to make sure I'd have a sufficient buffer if the weather was bad. You can use the above numbers to get a likely idea of what you will encounter, but I would not plan to be able to make it based on that. I would not plan any trip legs longer than 139 miles (2/3 of the 208-mile EPA rating) in a 60kWh car. Although it is possible that on the day of the trip if conditions were favorable, I may skip a charger if I think my usage will be low enough that I can make the next one. I'd still leave a good buffer though! You never know if you might encounter a sudden strong headwind.

    Between Barstow and Furnace Creek, there is an RV park in Shoshone that has 50A service. If I had a 60kWh car, I would plan on stopping there. There are a couple of other legs in there (i.e. Yreka or Orland, 155 miles) that I would not try in a 60kWh car without an emergency plan. There is probably something available in Redding; or there is a KOA in Mt Shasta City.

    By the way, for all of you thinking about a 60 kWh car and worried about the extra charging stops: note that while the 60kWh car can't take single legs as long as an 85kWh can, that does not mean it spends more time charging! You only charge long enough to replace what you used; if you stop more, you used less and so the charge stop is shorter. In fact, given that the 60kWh car's MPGe is 95 instead of 89 (it is unclear if the improvement is in consumption or charging overhead, but either means the same thing: shorter charging time) it is possible that the 60kWh may spend less time charging. This isn't always the case though - for example if two 17kW HPCs are 175 miles apart, the 85kWh car will do all charging at 17kWh, which the 60kWh car may have to spend some time at a 10kW campground in the middle.

    Wow, you're brave to do that trip with a single charger. Having to wait for 20kW charging is bad enough. I guess my first Roadster trip (back in 2010 when there were no chargers, so I had to use campgrounds) only used 10kW charging; but I'd sure hate to do it again. More Superchargers would fix this. So would a CHAdeMO adapter; you are passing CHAdeMO chargers along the freeway every 25 to 40 miles in WA and OR. In fact there's one a few feet from where you are charging at the Motel 6. Then you could charge at 48kW instead of 10kW and lop off 75% of the hours you are waiting for a charge. C'mon Tesla, get that adapter finished!

    (Say "hi" to the Motel 6 owners if they are there. They also own the Comfort Inn in Yreka, where I commonly charge at a Roadster HPC. On my last trip the timing didn't work out for me to stay at the hotel, and I felt guilty about using their free charger so I bought them a gift bag and took them for a ride).

    Good luck on the trip!

    -----------Edit--------------

    Perhaps a way to sum everything up in to a very easy way to take a trip:

    When planning a trip, never plan a leg without charging stops no farther than 2/3 of the EPA range of your car.

    While on the trip, stopped at a charger, if you want to know when you can leave, wait until your car says you have at least 150% of the miles needed to get to the next charger (note that my worst-case leg used 145% of the rated miles; and I wasn't going fast). You may be able to leave sooner than that, but only if you know the conditions ahead of you and do the math above.
     
  15. kimbapooch

    kimbapooch Member

    Joined:
    Jun 24, 2012
    Messages:
    7
    Location:
    Seattle, WA
    Chad, not sure a second charger would have helped me since 70A J-1772 units seem to be very rare in the wild and the standard L2 units and RV Park 14-50R outlets max out at 10KW or less anyway. If I had the elusive Roadster adapter it would be a different story as there are several Roadster HPC's along this route.

    Your point is VERY well taken regarding CHAdeMO. It's painful to park next to an unused station that has the power but not the interface to top me off in an hour or two. With Superchargers imminent I don't expect to see a CHAdeMO adapter for Model S anytime soon. Call me a pessimist.

    One more point. I've seen it mentioned here before but I'll say it again. NEVER EVER EVER trust a public J-1772 L2 unit to do an overnight charge without checking it frequently!!! I'll be spending an extra 6 hrs here at the Motel 6 because my charge aborted at 2:37AM this morning after 4.5 hours without a problem (and less than an hour after I last checked it before turning in). I don't know if it was the car or the EVSE that caused the charge to stop, I restarted it without issue, but Tesla needs to supply some sort of notification mechanism (email/text/in app notification) for interrupted charges! This should be BASIC functionality as it has a HUGE impact on cross country travel. Oh well, I guess the Siskiyou summit will just have to wait a few more hours for me to tackle it. My apologies for the off-topic rant.
     
  16. ChadS

    ChadS Petroleum is for sissies

    Joined:
    Jul 16, 2009
    Messages:
    2,401
    Right, sorry - along I-5 in WA, OR and Northern CA you'd need the twin chargers AND an HPC adapter to charge above 10kW. Fortunately I had both for my trip.

    I'm less pessimistic, because Tesla has to build one for other markets anyway, and they know that some states already have CHAdeMO chargers in places that Tesla NEVER plans to put Superchargers. Sure, there will be Superchargers on I-5 - but quite likely nowhere else in WA and OR, or example. But there are already dozens of CHAdeMO chargers in place. So I am pretty sure we will see an adapter...but I am very concerned about the availability date. Not having it has already cost me 18 hours or so of standing around, and I have more trips planned. This is exactly the sort of thing that keeps most of my friends from buying a Tesla (even though few of them would be likely to take a long trip in it).

    I hear ya. After my first Roadster trip 3 years ago, I sent Tesla an email saying the car had worked very well, but I begged for ONE important change - a notification when charging stops for any reason. That cost me many hours on that trip. Tesla said that that feature was "being worked on". 3 years later, Tesla still doesn't offer it. You can add OVMS to a Roadster, but Model S owners are still out of luck. I hope and assume that Tesla's mobile app will have it...and that the mobile app will be released soon!
     
  17. kimbapooch

    kimbapooch Member

    Joined:
    Jun 24, 2012
    Messages:
    7
    Location:
    Seattle, WA
    Since my previous post the public J1772 L2 EVSE I'm using just aborted it's charge again. I realize this is a bit off topic but since I suspect folks reading this thread may be interested in cross country travels I'll post one last time.

    The unit I'm on is an Aerovironment EVSE-RS+ Level II. It is on their network and part of the OUTSTANDING West Coast Green Highway initiative. It worked great when it worked except that I was in the rare position to observe (with some help from their customer service who checked their charge session logs) that it stopped charging TWICE after EXACTLY 4hrs and 35 minutes! While Aerovironment denies there being any sort of timer or limit in place, I doubt very much that the car is causing it (although I will be contacting ownership experience to let them know about this just in case). While this would not normally be an issue if you were topping off while grabbing a burger, it's a real buzzkill when you're charging overnight at a hotel expecting a full charge for your next day of travel.

    The takeaway is NEVER trust a networked public L2 charger and if you're planning to charge overnight at the Motel 6 off I-5 near Oakland, OR be sure to set your alarm for 4hrs and 36 minutes after you start your charge because it will likely have shut off. No idea how other L2s in their network or in other networks behave but BEWARE. Happy travels!
     
  18. Kipernicus

    Kipernicus Model S Res#P1440

    Joined:
    Dec 2, 2009
    Messages:
    1,172
    Location:
    Belmont, CA
    This is true, but sometimes it means the 60 spends that time charging on the road but the 85 spends that time charging at destination.
     
  19. dsm363

    dsm363 Roadster + Sig Model S

    Joined:
    May 17, 2009
    Messages:
    18,235
    Location:
    Las Vegas, NV
    Great information. You should turn that into a blog post on TMC as well.
     
  20. neroden

    neroden Happy Model S Owner

    Joined:
    Apr 25, 2011
    Messages:
    3,572
    Location:
    Ithaca, NY, USA
    This is a suspiciously exact number; it looks to me like there's a software bug. Perhaps it's counting seconds and using a 14 bit field to keep track of how many have elapsed; that could do it.
     

Share This Page