Tesla's 85 kWh rating needs an asterisk (up to 81 kWh, with up to ~77 kWh usable)

[MP3Mike]

I hate it as much as the next guy, but it seems the automotive industry wants to advertise battery nameplate capacity and not actual usable capacity. I wish it weren't that way, but it is. Tesla has to operate in this environment, and so it seems they decided to do what all of the other guys have done and advertise nameplate (i.e. meaningless) capacity.

For example:

A BMW i3 is advertised as 22kwh battery with actual usable capacity of 18.7 kwh, thus only 85% of nameplate capacity is available to the owner.

A Nissan leaf is advertised as a 24kwh battery with only 21.3kwh actually usable, thus 88.8% of nameplate capacity is available to the owner.

That is comparing apples and oranges unless you know what the total actual capacity of the i3 and Leaf is. Are they using the difference as the anti-brick buffer? That certainly seems reasonable to me. (In which case they aren't overstating the actual capacity at all.)

For the Tesla Model S85 they are saying 85 kWh, but it is really only 81 kWh with 77.5 kWh available.
For the Tesla Model S60 they are saying 60 kWh, but it is really 61 kWh with 56 kWh available.

It seems like a 3-4 kWh anti-brick buffer is pretty standard on everything except the Model S60, which by your numbers has a 5 kWh buffer.

I think that the usable number that you are looking for is reflected in the EPA rating.

 

[FlasherZ]

To that argument, I would say that 265 miles on a charge is at best, wishful thinking. With temperature being such a factor, none of us have ever seen close to 265 in the real world. And extra 4kw would have actually allowed almost everyone to get that number.

That is flat out wrong. I can get 265 at speed limit plus 5 mph if it is over 55 degrees outside.

 

[ohmman]

That is flat out wrong. I can get 265 at speed limit plus 5 mph if it is over 55 degrees outside.

I've gone 257 at 10 over before, including an elevation gain. I believe I had a favorable tailwind, though.

 

[Benjamin Brooks]

That is flat out wrong. I can get 265 at speed limit plus 5 mph if it is over 55 degrees outside.

Is that a 40mph speed limit?

 

[tom66]

The 85kWh car should do almost 300 miles at 55mph, so it depends on what the speed limit is. Most roads in California max out at 65mph right?

 

[FlatSix911]

After reading the last 19+ pages of discussion ... I have to agree that Tesla has not been entirely honest.
At best, they mislead customers with the marketing and badging of their models with the 85 kWh designation.

Soon to be announced, the 85 has already been discontinued in Canada and some speculate in the US shortly.
I wonder how the 70 and 90 kWh batteries will stack up when benchmarked and tested independently in the lab?

 

[Max*]

Ouch. Where are you getting the 83 number from?

Tesla states ~6% more range for the 90, which assuming that the 85 is really 81 would be 85.9 kWh. If it is really only 83 kWh then you are only getting a ~2.5% boost in capacity, and getting "cheated" out of ~3 kWh...

I believe hee talking about the P90DL, not a 90D (using the 310wh/mi number).

Please correct me if I'm wrong.

 

[McRat]

The 85kWh car should do almost 300 miles at 55mph, so it depends on what the speed limit is. Most roads in California max out at 65mph right?

70mph on some interstates. Flow of traffic is usually 75-80 on the interstates outside of urban sections.

 

[AWDtsla]

I believe hee talking about the P90DL, not a 90D (using the 310wh/mi number).

Please correct me if I'm wrong.

That's right. But math still works if you use a 90D, using 90D numbers.

edit - actually, someone please confirm what Wh/mi rated is for 90D. Just wait until the dashed line lines up with the solid line in energy analyzer.

 

[jeffro01]

I'm torn here. I also wish 'wk' had more data to work with, IE a 70 and 90 pack, as I have the 90 pack and well my 90% is only 246/247 which is already starting to concern me as it should be 286 miles to full per the Tesla website but I'm really looking at 271 just from adding 10% to my 90%. That's 15 miles which to me is a concerning number.

I can say that for me, I care about range, not kWh but I also paid more for the 90 pack to get more range and from what I have read in some of the other threads I'm not sure if I'm really getting more range... That to me would be a major issue if I was lied to about getting more range when I really am not seeing anything better than the 85's are supposed to be getting because as it stands, my 90 pack is looking like it's barely going to get the advertised 270 the 85 pack gets... Certainly not 6% more.

My point here is I care about range, not actual kWh numbers but I had better get the additional range I paid for or otherwise I see that as false advertising which I'm not a fan of. So from that perspective I can see how those who are fixated on the kWh number would be upset\angry\frustrated.

It's all a matter of perspective. Oh and can anyone else talk me off the ledge (feel free to PM me so I'm not distracting from this) regarding what I'm seeing with my 90 pack? It just doesn't feel right...

Jeff

 

[AWDtsla]

I'm torn here. I also wish 'wk' had more data to work with, IE a 70 and 90 pack, as I have the 90 pack and well my 90% is only 246/247 which is already starting to concern me as it should be 286 miles to full per the Tesla website but I'm really looking at 271 just from adding 10% to my 90%. That's 15 miles which to me is a concerning number.

I can say that for me, I care about range, not kWh but I also paid more for the 90 pack to get more range and from what I have read in some of the other threads I'm not sure if I'm really getting more range... That to me would be a major issue if I was lied to about getting more range when I really am not seeing anything better than the 85's are supposed to be getting because as it stands, my 90 pack is looking like it's barely going to get the advertised 270 the 85 pack gets... Certainly not 6% more.

My point here is I care about range, not actual kWh numbers but I had better get the additional range I paid for or otherwise I see that as false advertising which I'm not a fan of. So from that perspective I can see how those who are fixated on the kWh number would be upset\angry\frustrated.

It's all a matter of perspective. Oh and can anyone else talk me off the ledge (feel free to PM me so I'm not distracting from this) regarding what I'm seeing with my 90 pack? It just doesn't feel right...

Jeff

Do a full charge to 100%, and wait until it actually stops pulling power.

 

[FlasherZ]

Is that a 40mph speed limit?

Combination of 35 in town, 55 state hwy, and 70 on interstate hwy.

 

[Max*]

Jeff, minor nitpick, you can't "just" add 10%. I don't think it's linear, at least I can't just add 10% to my 90% to get 100% SOC.

Also, 90%/246 miles would make 100%/273 miles, not 271. Assuming it's linear, which I don't think it is

 

[brkaus]

I would still purchase the 85 over the 60 for the performance. As wk says, the cars would still sell.

 

[Evbwcaer]

Wk057, thanks for all of the awesome posts, work, and research. I am wondering what you make of the following (originally posted by me, S85)?:

"I do wonder about the useable capacity of my 85kwh battery. I used 70.9KwH, and had 15 rated miles left (15*290=4,350=4.35KwH). That implies a useable 75.25KwH. Had my car charged to 272 rated miles that would have been 7 more miles (7*290=2,030=2.03KwH) so would be 77.28 useable if rated equals 290WH/M. If rated equals 300 then I would have 81.6kwh. <--Just thinking out loud."

My 2014 S85 was range charging to 272 at the time, April of 2015, and trip I reference was 257 miles according to my car.

My other question for you, and others too I guess, deals with regen. I guess it is reasonable to assume that in 200-300 miles of driving there is going to be some regen. If Tesla made the assumption that a small number of KwH's would be recovered through regen, would it be fair to add those KwH's too the advertised battery capacity? In an absolutist way of looking at it, which is not unreasonable, regen should not be considered. In a real world way of looking at it, in almost all cases there will be a meaningful amount of regen over 200-300 miles, and because the car has not been plugged it, it could be capable of delivering (85KwH's - Safety Capacity KwH's) on one charge.

People are seeming to like ICE analogies here. What if a car advertised an 11 gallon tank, but it was really only 10, and over the course of driving (10 gallons X the rated MPG) miles, an additional gallon "magically" dripped into the tank. Would that be a 10 gallon tank or an 11 gallon tank?

Thoughts.

 

[SteveG3]

Good theory, but his cells are from an A/B pack, the first Model S's off the line.

I can understand your confusion, but thusfar, wk057 has not stated which pack variation the cells he put under the testing he is discussing came from.

here's what wk057 said in the first post of this thread as to the origin of the cells he did the month long test on,

"I presently have had roughly 20 pairs of cells from Tesla's "85" kWh pack running 24/7 doing various cycle tests in various conditions. (Eventually I'll be posting detailed data from these tests, but I want to give them significant run times.) These cells were from a pack that had less than 1000 miles (or less than 5 charge cycles) on it, and arrived to me charged to roughly 50% (perfect for storage/shipment)."

understandably, you may have confused wk057's discussion of Panasonic cells with an "A" or "B" designation in comment #48 of this thread with Tesla packs "A" and "B."

- - - Updated - - -

The energy required to travel for one hour at 60 mph in a 5000 lb tesla versus a 4500 lb (10% weight reduction) is only reduced by 0.6 kWh. Four hours is a 2.4 kWh reduction in energy for the lesser weight. The weight is a linear effect and only applies to the rolling resistance force component of the load, aerodynamic drag is nonlinear and is a much bigger factor than weight above about 50 mph.

View attachment 110244

okay, so at 60 mph the Model S has roughly 300 miles of range. so, if I'm not misunderstanding you, 10% less weight would mean 0.6 kWh change in energy needed to travel at that speed per hour... or 3 kWh for the total time to use the vehicle's range capacity. I don't know the source of your data, but it is quite consistent with the point I'm making.

what's more, when you consider that the EPA range is not determined by traveling at 60 mph, but rather by a 5 cycle test, where the cycles average 8.8 miles of length and 11 stops, clearly it is extremely plausible, a 10% weight reduction could easily allow for 4 kWh reduction in battery size to the vehicle while maintaining the 265 mile range.

 

[JRP3]

My other question for you, and others too I guess, deals with regen. I guess it is reasonable to assume that in 200-300 miles of driving there is going to be some regen. If Tesla made the assumption that a small number of KwH's would be recovered through regen, would it be fair to add those KwH's too the advertised battery capacity ?

No. There is always a loss with regen, and all the energy "recovered" with regen originally came from the charge put into the pack. Regen simply makes the car more efficient than just using brakes.

 

[SteveG3]

You keep making this claim that some small % of weight loss can offset the loss of 4 kWh. Where's your data to support this? Again, as an owner of two Model S and the previous owner of a 3rd, I know for sure that the weight loss would not be the same as 4 kWh, and I'm certain other owners would concur. If so, then driving around with a couple of people in the car would cost 4 kWh of power vs just a driver. This just isn't the case.

Please return when you have data to back up your claims. I'm not going to waste any more time debating the point until then.

please see comment #196, as I explain,

1) looking at what kennybobby posted, a 10% weight reduction seems consistent with a 3 kWh smaller battery being able to do the same range as a heavier car with the larger battery.

2) we are talking about EPA testing cycles, where the value of reduced weight would be magnified. the EPA range rating is derived from their 5 cycle test... the cycles average 8 stops over 11 miles. extrapolating the impact of adding ~400 pounds of weight from your recollection of the long distance trips you described upthread simply does not match the EPA range rating testing that averages nearly 1.5 stops per mile.

 

[JRP3]

1) looking at what kennybobby posted, a 10% weight reduction seems consistent with a 3 kWh smaller battery being able to do the same range as a heavier car with the larger battery.

Where do you see a 10% weight reduction in the 85?

https://www.teslamotors.com/support/model-s-specifications

Curb weight 4,647.3 lbs

https://en.wikipedia.org/wiki/Tesla_Model_S

• 1,961 kg (4,323 lb) (60)[SUP][7][/SUP]
• 2,085 kg (4,597 lb) (60D)[SUP][8][/SUP]
• 2,090 kg (4,608 lb) (70D)[SUP][9][/SUP]
• 2,108 kg (4,647 lb) (85)
  
• 2,188 kg (4,824 lb) (85D)[SUP][8][/SUP]
• 2,239 kg (4,936 lb) (P85D)[SUP]https://en.wikipedia.org/wiki/Tesla_Model_S#cite_note-rat-2014-10-09-8[/SUP]

http://www.edmunds.com/tesla/model-s/2015/sedan/st-200725283/features-specs/

CURB WEIGHT 4647 lbs.

http://www.edmunds.com/tesla/model-s/2013/sedan/features-specs/

CURB WEIGHT 4647 lbs

 

[SteveG3]

having reread wk057's original post, I have now two alternative hypothesis to wk057's hypothesis... the new one, cell degradation.

I base it on this part of the original post,

"I presently have had roughly 20 pairs of cells from Tesla's "85" kWh pack running 24/7 doing various cycle tests in various conditions. (Eventually I'll be posting detailed data from these tests, but I want to give them significant run times.) These cells were from a pack that had less than 1000 miles (or less than 5 charge cycles) on it, and arrived to me charged to roughly 50% (perfect for storage/shipment)."

and

"In 6 hour charge/discharge cycle testing (1/6C charge and discharge) over a one month period the average capacity of the cells came out to 11.36 Wh per cell. The maximum capacity measured was 11.42 Wh/cell."


we can see from those comments,

- wk057 reports the pack as having had 1,000 miles on it
- reports continuous testing doing 2 charge and discharge full cycles a day for a month... the equivalent of 60 full charges and discharges, which in the real world would mean ~15,500 miles (based on 260 miles per cycle)
- this month straight of charging of discharging was done not within the pack with it's management system

if wk057 took data after each cycle, this means the cells had on the average point when data was taken the equivalent of 8,750 miles on them, with an average of 15 straight days of continuous charge and discharge, all without the benefit of a battery management system.

would anyone really find it shocking if a Model S starting with 1,000 miles had it's battery management system turned off, and for thirty days was continuously charged and discharged and ended up with 4% degradation? my 2012 Model S with 12,000 miles has 3-4% degradation, but trust me, I wouldn't let anyone subject it to the conditions of wk057's testing to see how it would handle another 15,500 miles put on by nonstop charging and use without the benefit of the battery management system.