samcarney
Sam C
120VAC @ 12amps will give you 4.8 miles for every hour of charge. There is a formula that I find very useful for computing range at various volt/amp combinations. VOLTS times AMPS divided by 300.
Good luck
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Charging the Roadster
- Thread starter malcolm
- Start date
120VAC @ 12amps will give you 4.8 miles for every hour of charge. There is a formula that I find very useful for computing range at various volt/amp combinations. VOLTS times AMPS divided by 300.
Good luck
That's MY formula
and it is VERY useful , and it works well at 200+ volts, less so at 120V, especially if ESS battery cooling overhead is needed. For 120V*12A the very conservative low end estimate is probably 3.0 miles-per-hour-charged, 3.5 more likely, and 4.8 as a best case. You'd benefit from 15A -- if the circuit will allow it -- for 25% improvement. So that's what my 35-50 miles in 10 hours estimate is based on.Still hoping to find you 240V ... and if you can borrow an RFMC or UMC.
tomsax
Member
My range record is 182.6 miles going 55-60 mph on level freeway, with 61 IM reported at the end, done on March 3, 2010. That was starting with a range mode charge of 243 IM.
After the firmware update this summer, I'm only getting 234 or so IM on a full range mode charge (reportedly due to the recalibration of how the state of charge is computed with the firmware update this summer, 3.5.17 for 2008 Roadsters).
Interesting formula. By my experience, your formula gives good values for 240V at 16A and 24A, but gives an underestimate at higher charging rates. Because of charging overhead, I would expect your value to be high for 120V/12A. My experience (from September, 2009, several firmware updates ago) was 34 ideal miles in 11:30, or just barely under 3 IM/hr. Do you have data to support the 4.6 IM/hr number?
Chris, my guess is that your trip would be a real nail biter if you only charge for 10 hours at 120V/12A. It would be a big help if you can charge at 16A from a 20A circuit. Because of charger overhead, that makes a bigger difference than you'd expect from increasing the current by a third. By the 2008 owner's manual, it doubles the charging rate, although I think they've improved 12A charging since then. Look for a NEMA 5-20 outlet. Now that I'm tuned into looking for them, I'm amazed how common they are.
After the firmware update this summer, I'm only getting 234 or so IM on a full range mode charge (reportedly due to the recalibration of how the state of charge is computed with the firmware update this summer, 3.5.17 for 2008 Roadsters).
Interesting formula. By my experience, your formula gives good values for 240V at 16A and 24A, but gives an underestimate at higher charging rates. Because of charging overhead, I would expect your value to be high for 120V/12A. My experience (from September, 2009, several firmware updates ago) was 34 ideal miles in 11:30, or just barely under 3 IM/hr. Do you have data to support the 4.6 IM/hr number?
Chris, my guess is that your trip would be a real nail biter if you only charge for 10 hours at 120V/12A. It would be a big help if you can charge at 16A from a 20A circuit. Because of charger overhead, that makes a bigger difference than you'd expect from increasing the current by a third. By the 2008 owner's manual, it doubles the charging rate, although I think they've improved 12A charging since then. Look for a NEMA 5-20 outlet. Now that I'm tuned into looking for them, I'm amazed how common they are.
strider
Active Member
Thanks for the info. It looks like I'd be right on the ragged edge. I'm heading from San Mateo, CA to here: 15501 Meiss Road, Sloughhouse, CA 95683 for a shooting competition. I'm going to e-mail to ask them about any 220V access but I'm guessing it'll just be 120V @ 12A. I have a friend who lives in Pleasant Hill who is going to the match so maybe I'll just leave my car at his place and ride with him.
Or ... reverse that. Pick up you friend in Pleasant Hill, take I-80, and charge at 70A in Davis and/or Vacaville (40A) while enjoying a cup of Java. What day is the competition ?
Edit: Vacaville might only be 32A. Fairfield is 40A. (Note: all three suggested locations are Tesla ClipperCreek HPCs and won't require RFMC/UMC.)
Edit: Vacaville might only be 32A. Fairfield is 40A. (Note: all three suggested locations are Tesla ClipperCreek HPCs and won't require RFMC/UMC.)
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I Agree, take I80 and plan some time to stop in Davis on the way up,back or both. plenty of places to get food or coffee within walking distance of the charge point (70a/208v tesla HPC). I do this all the time on my way from Oakland to Sacramento or Tahoe.
strider
Active Member
Hi Guys,
Just charged for the first time in range mode as was going on a long journey. I was a bit surprised when fully charged that it said "Ideal range 226 miles". Estimated range was 139. The car had only just finished charging at this point.
How is the ideal range calculated? I would have expected the ideal range on a full charge to be 245 miles unless my battery pack has already lost some capacity (2010 car with 2000 miles).
Thanks
Alan
Just charged for the first time in range mode as was going on a long journey. I was a bit surprised when fully charged that it said "Ideal range 226 miles". Estimated range was 139. The car had only just finished charging at this point.
How is the ideal range calculated? I would have expected the ideal range on a full charge to be 245 miles unless my battery pack has already lost some capacity (2010 car with 2000 miles).
Thanks
Alan
kgb
Member
I stumbled upon Alan's post, and I noticed something similar with my first full charge (this am:biggrin. It was either earlier in this thread or in another, but I recall a discussion of everyone's ideal miles after a full standard charge. I just did my first full standard charge and it was only 180 miles. Does this get better after a break-in, or is this just the way my battery is going to be?
. It was either earlier in this thread or in another, but I recall a discussion of everyone's ideal miles after a full standard charge. I just did my first full standard charge and it was only 180 miles. Does this get better after a break-in, or is this just the way my battery is going to be?in standard mode - that sounds about right.
in range mode - you will get the 244 ideal miles.
It depends on how you charge - you can change the settings in the touch screen.
Also note: ideal miles aren't very useful unless you plan to drive like your grandma estimated miles is what you actually have.
in range mode - you will get the 244 ideal miles.
It depends on how you charge - you can change the settings in the touch screen.
Also note: ideal miles aren't very useful unless you plan to drive like your grandma
estimated miles is what you actually have.
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tomsax
Member
ideal miles aren't very useful unless you plan to drive like your grandma
I respectfully disagree and hold the opposite point of view.
Ideal miles is a representation of how much energy is left in the battery pack, more accurate than guessing the percent from the bar. It's the number of miles you have left if you drive, for example, at a steady 55 mph. If you're low enough that you care then the ideal miles tells you how much you need to moderate your driving to get the miles you need.
The estimated miles are based on some unspecified measure of how you've been driving recently. Since you don't know how your driving over some unspecified recent period is scaling the energy left in your pack, it tells you very little about what's left in the battery pack.
I think that the range for the European cars is set to 211 miles / 340 Km, vs the 244 miles on US cars.
Probably due to the test cycle being different in Europe..
When standard charging the roadster i nomally get around 302 km/ 188 miles of ideal range. I can't remember what i got when i was charging in range mode..
I agree with this statement but would point out that there are other factors that need to be considered carefully on longer trips. First and foremost is the affect of a strong headwind. Driving 55 mph into a 20 mph headwind is equivalent to driving 75 mph in energy usage. The other factor to be aware of is the net elevation gain of the trip.
Tomsax - You may be right but...
It has just been my experience so far that I get very close to what my estimated miles are - compared to the ideal miles.
If my charge says ideal 300km (Canada) and estimated 240km - I know that the best I can do driving in 'real conditions' is 240km - in fact a few times I ran to near zero km left when I had driven almost exactly 240km - good thing I wasn't watching my ideal miles which said I had 40km left when I really had zero left........also my ideal km magically changed from 40km to zero km in an instant at this point.....and then the dreaded touchscreen warnings start appearing......
So sure it says I could have gone 300km "driving like a grandma" at mediocore speeds and conditions - however I don't find that realistic. For me anyways.
I do not drive at a steady 55 mph (I didn't realize a roadster can go that slow.....hehe)
It has just been my experience so far that I get very close to what my estimated miles are - compared to the ideal miles.
If my charge says ideal 300km (Canada) and estimated 240km - I know that the best I can do driving in 'real conditions' is 240km - in fact a few times I ran to near zero km left when I had driven almost exactly 240km - good thing I wasn't watching my ideal miles which said I had 40km left when I really had zero left........also my ideal km magically changed from 40km to zero km in an instant at this point.....and then the dreaded touchscreen warnings start appearing......
So sure it says I could have gone 300km "driving like a grandma" at mediocore speeds and conditions - however I don't find that realistic. For me anyways.
I do not drive at a steady 55 mph (I didn't realize a roadster can go that slow.....hehe)
strider
Active Member
IIRC, during my test drive the salesperson told me that estimated miles are based on an average of your last 30 miles driven. So assuming you continue to drive like you had for the last 30 miles then estimated miles are what you'll get.
I believe tomsax's point is that if it looks like estimated miles are going to come up short for where you need to go you could change your driving style to try and get closer to ideal miles.
Also, the gauge says "Ideal" miles - it's assumed that would be w/o headwinds and hills
I think that Tom's point was that ideal miles are a consistent unit of measure.
It may help to not think of them as miles but as points. Your battery pack has a max of 244 points in it ( range mode ).
One of the most important times to think in terms of ideal miles is when charging - when charging you want to get an accurate reading of what is going into the battery without the estimated mile fudge factor. On long trips I have found thinking in ideal miles and doing my own conversion more useful than estimated miles.
It may help to not think of them as miles but as points. Your battery pack has a max of 244 points in it ( range mode ).
One of the most important times to think in terms of ideal miles is when charging - when charging you want to get an accurate reading of what is going into the battery without the estimated mile fudge factor. On long trips I have found thinking in ideal miles and doing my own conversion more useful than estimated miles.
IIRC, during my test drive the salesperson told me that estimated miles are based on an average of your last 30 miles driven. So assuming you continue to drive like you had for the last 30 miles then estimated miles are what you'll get.
I believe tomsax's point is that if it looks like estimated miles are going to come up short for where you need to go you could change your driving style to try and get closer to ideal miles.
Also, the gauge says "Ideal" miles - it's assumed that would be w/o headwinds and hills
This I understand - and that makes sense to me as well. However - I guess what I am getting at is that if you want to just drive at whatever speed you decide and do not want to worry about adjusting your driving habits - if you use the estimated range it is safer to go by that than ideal range.
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