scole04
Member
+1
As an ee myself i questioned the logic of adding ballast when overall efficiency is the goal. EPA numbers are what i expected.
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+1
As an ee myself i questioned the logic of adding ballast when overall efficiency is the goal. EPA numbers are what i expected.
Clearly overall efficiency isn't the only goal. (If so the car would look and drive very differently.) It's just one of many, including overall cost and time to market. We don't actually know if they're adding ballast, and while conceptually it may be counterintuitive and offputing, if the car works and performs as advertised it shouldn't really matter. That said, I'd still like to know if they chose to use ballast or not.
When the NHTSA receives their "off the line" vehicle for testing, regardless of whether they get a 40, 60, 85, or 85 Perf presumably Tesla wants to do whatever they reasonably can to make sure that the NHTSA considers the results applicable to the other 3 flavors. Such accomodations might include specific weight and front/rear balance requirements.
EcoHeliGuy
Member
Lets consider they are using less of the same cells then the 85kw Model S
-they don't need to add ballast, I can't think of a reason why any engineer would ever want to handy cap there own work.
-for structural support in crash tests they would have three easy options, still install the empty battery cell boxes seen in the main pack, replace empty battery boxes with light honeycomb, just use bracing.
- each model has lower max speed and lower 0-60 times as you get a smaller pack this is most likely ratio changes in the single speed gear box. They are sacrificing speed for efficiency. Also tesla has only ever mentioned two motors, performance and none performance. So for simplicity each non performance car will likely have the same motors.
-look at the battery warranties, they also go down with the capacity of the pack, this indicates they most be using the same batteries only fewer. And they are going through much larger cycles. With 85kw you aren't cycling the batteries much day to day for an hours drive. But in the 40kw your using the majority of the capacity to travel the same distance.
-the software, chargers, algorithms, are so complex and took so many man hours, there is no way tesla tripled their work to use three different battery types. Gear box ratios would take a fraction of the time to impalment.
-they don't need to add ballast, I can't think of a reason why any engineer would ever want to handy cap there own work.
-for structural support in crash tests they would have three easy options, still install the empty battery cell boxes seen in the main pack, replace empty battery boxes with light honeycomb, just use bracing.
- each model has lower max speed and lower 0-60 times as you get a smaller pack this is most likely ratio changes in the single speed gear box. They are sacrificing speed for efficiency. Also tesla has only ever mentioned two motors, performance and none performance. So for simplicity each non performance car will likely have the same motors.
-look at the battery warranties, they also go down with the capacity of the pack, this indicates they most be using the same batteries only fewer. And they are going through much larger cycles. With 85kw you aren't cycling the batteries much day to day for an hours drive. But in the 40kw your using the majority of the capacity to travel the same distance.
-the software, chargers, algorithms, are so complex and took so many man hours, there is no way tesla tripled their work to use three different battery types. Gear box ratios would take a fraction of the time to impalment.
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SuperCoug
Model S Res #7734
I know I've seen this several places on these forums but I'm having problems finding this information.
My question is "How many KWHs does it take to fully charge a 60 KWH car?" or another way to ask it "What is the efficiency of the charger?"
I will be charging on a 240 volt 50 AMP NEMA 14-15 outlet. I remember reading that 120 volt charging was not quite as efficient since not as much energy is left over for the car once cooling and other overhead processes are taken into consideration.
My question is "How many KWHs does it take to fully charge a 60 KWH car?" or another way to ask it "What is the efficiency of the charger?"
I will be charging on a 240 volt 50 AMP NEMA 14-15 outlet. I remember reading that 120 volt charging was not quite as efficient since not as much energy is left over for the car once cooling and other overhead processes are taken into consideration.
85 kWh S: Range = 265 miles at 38 kWh/100 mi = 100.7 kWh
60 kWh S: Range = 208 miles at 35 kWh/100 mi = 72.8 kWh
24 kWh LEAF: Range = 73 miles at 34 kWh/100 mi = 24.8 kWh
Calculations above performed using EPA efficiency numbers. The EPA ratings are kWh from the wall so includes charging efficiency.
The tesla website (Model S specs page) quotes: "Peak charger efficiency of 92%". Presumably this is the charger itself, not counting the various auxiliaries which will vary according to ambient temperature etc.
The article was well-written, but it seems to have been researched entirely by reading posts in this thread and elsewhere on TMC. Which isn't to say that a good summary isn't valuable.
EcoHeliGuy
Member
It also never mentioned the most likely reason, and that being different gear ratio and less weight. The 60, and the 40 most likely use the same motor as only mention of a different motor was in the performance model. But the 60, and 40 have different top speeds and acceleration profiles. This suggest higher gear, which if the car weights less makes sense.
The first few 60kWh's have been delivered and it's been confirmed that they weigh the same as the 85kWh units -- at least according to the door sticker... see First 60kWH delivery notice or email - who will it be?
I hadn't thought about the gear ratio being different... I guess that's possible. I am sure there are all kinds of parameters that could be tuned actually...
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One theory that I heard from de704 was that the testing methodology used on the 85kWh battery was actually changed by the time they did the testing on the 60kWh battery, and that the two batteries actually have the same relative efficiency... That sounds more plausible now, and if so that would mean the 85kWh battery could eventually get retested under the new guidelines and come out with a higher range...
I hadn't thought about the gear ratio being different... I guess that's possible. I am sure there are all kinds of parameters that could be tuned actually...
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One theory that I heard from de704 was that the testing methodology used on the 85kWh battery was actually changed by the time they did the testing on the 60kWh battery, and that the two batteries actually have the same relative efficiency... That sounds more plausible now, and if so that would mean the 85kWh battery could eventually get retested under the new guidelines and come out with a higher range...
Are you (and de704) talking about the charging efficiency (wall-to-battery) or consumption efficiency (battery-to-road)? Or both?
DFibRL8R
Active Member
This is not correct. The door stickers of the 85 and 60 kWh's list the GVWR which is the maximum operating weight of the vehicle including passengers/cargo etc. It makes since that these are the same for the 2 since they can handle the same weight. We will be interested in the curb weight of the 2 which is weight of vehicle without passengers/cargo and.
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hans
P631
Yup, the door sticker is a red herring. Doesn't tell us anything about the weight of the car or the battery. I should have just RTFM since it's there in back and white.
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Most I got with a range charge was 197 miles on the display although it charged for at least 30 minutes without going higher. I drove it ~10 miles before it changed to 196 miles on the display. Anyone with a 60 see similar behavior?
Standard charge was 185 miles (projected) on the NEMA 14-50 and 190 miles on the Gilroy Supercharger. Oh, and did I mention, this car is awesome! No regrets on getting the S60 vs the S85 or P85.
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