40kwh Model S canceled

[wraithnot]

Im sorry...WHO EXACTLY said the performance would be upgraded? It's all a bunch of software tricks...so whose to say they don't just limit the performance as well? The software could easily keep it at a 6 sec 0-60 car. (I'm NOT saying that's what they will do...only that they could and might...and that would totally be fair since that's all you are paying for!).

The only thing you can't argue is the HARDware...which is now clearly 60kw....so I very much agree with the arguments that their battery life should theoretically be better than most (since they will never be at the extreme end of "empty". They will still be exposed to the extreme end of being fully charged like the rest of us though (with range charging).

The Tesla press release addresses the performance issue directly: "The customers who ordered this option will instead receive the 60 kWh pack, but range will be software limited to 40 kWh. It will still have the improved acceleration and top speed of the bigger pack, so will be a better product than originally ordered, and can be upgraded to the range of the 60 kWh upon request by the original or a future owner."

The press release doesn't give the details of the software range limiting. But I assume that it would keep you from charging past 40 kWh rather than shutting down the car with 20 kWh left since stranding someone when there is still plenty of charge in the battery seems really lame.

 

[Oyvind.H]

on a similar/related note. I wonder how much more battery degradation us P85 owners are gonna have (compared to standard 85)? Remember its the extremes that kill the battery (going close to zero range, fully charging in range mode, etc.). It makes sense that flying 0-60 in 4 secs with all those electrons traveling EXTREMEly fast would take a toll in the battery as well.....

I haven't seen this brought up on the forums yet.... can one of our physics/engineering types chime in on this one?

Interresting question. People worry about supercharging at 90kW, but not about a 300kW discharge

 

[jkirkebo]

The press release doesn't give the details of the software range limiting. But I assume that it would keep you from charging past 40 kWh rather than shutting down the car with 20 kWh left since stranding someone when there is still plenty of charge in the battery seems really lame.

I assume they will do just that (charge to 100% in range mode and remove the bottom 33%). This is for two reasons:

- 40kWh limited cars get the same performance as 60kWh. If the battery is never fully charged (but stops at 66% SOC) it will have to work harder to deliver the same performance.

- If you miscalculate range and get stranded, you always have the 20kWh in reserve. So you could choose between a tow truck or calling Tesla to upgrade on the spot and continue driving. Great incentive to upgrade if you ever run out.

 

[yobigd20]

Well I just thought of something interesting....(didnt read above posts to see if someone beat me to this)... the 'longevity' of the "40kWh" might last longer than the 60s and 85s. Hear me out - if it is software limted to 40, therefore 1/3 never being used, it is possible that Tesla uses an algorithm to do a sort of round-robin use. e.g., one "drive/recharge" could use packs 1,2,3,4 next charge could use packs 2,3,4,5, next charge could use 3,4,5,6, than back to 1,2,3,4 therefore increasing the lifespan of the batteries since once of the packs don't get used as often. Unless instead they are all charged fully and all drain simultaneously but limited to where 0 miles = 33% battery remaining across all packs.

 

[wraithnot]

I assume they will do just that (charge to 100% in range mode and remove the bottom 33%). This is for two reasons:

- 40kWh limited cars get the same performance as 60kWh. If the battery is never fully charged (but stops at 66% SOC) it will have to work harder to deliver the same performance.

- If you miscalculate range and get stranded, you always have the 20kWh in reserve. So you could choose between a tow truck or calling Tesla to upgrade on the spot and continue driving. Great incentive to upgrade if you ever run out.

Limiting the top end of the battery would be extremely simple- perhaps requiring changes to only a few lines of code. Based on what others on this forum have said, a standard charge stops when the individual cells get to 4.10 volts and a range charge stops at 4.15 volts. Just change those values and you're done. As the battery runs down, it seems like there is a really complex series of steps that are executed to keep the battery from bricking itself. Modifying that series of steps to happen at different voltages seems like a real pain. You would also have to change how the range is calculated.

Oyvind.H's proposal would be the best for the battery. But the whole reason they cancelled the 40 kWh option was to simplify things so I bet they will go with the simplest solution for the software range limit.

We could always bet the cost of a nice dinner on this if I'm ever in Norway or you are ever in San Francisco.

 

[WarpedOne]

if it is software limted to 40, therefore 1/3 never being used, it is possible that Tesla uses an algorithm to do a sort of round-robin use. e.g., one "drive/recharge" could use packs 1,2,3,4 next charge could use packs 2,3,4,5, next charge could use 3,4,5,6, than back to 1,2,3,4 therefore increasing the lifespan of the batteries since once of the packs don't get used as often.

They would need to change/add extra hardware to enable such scenario which in the end would add nothing to reduce battery wear, it may even increase it.
It is simple really - instead of letting SOC drop to 10%, report empty when SOC reaches 40%. Battery degradation increases with discharging very low or charging very high.
Besides SOC is not a measured quantity, it is a deduced one. Computer monitors kWh that went in, kWh that came out already and cell voltage under different loads.

I bet they will go with the simplest solution for the software range limit.

That is a given, it only depends on what simplest solution covers all the bases. It has to work with existing 60 kWh hardware and has to fulfill the 60 kWh loads (i.e. max power delivery, ....). Bottom limiting the 60 kWh pack is the simplest way of doing it. Top-limiting would change typical battery loads at max power delivery.

 

[Martini]

One of the problems with the 40 is that the longevity would be decreased due to the likely increased need to charge to 100% --- that is no longer an issue. Heck, the "40" will last the longest now, since it can be charged to "100%" yet it really will only be 66%, and hence have a much improved battery use pattern.

Yep, "Range mode" will be the new "Standard Mode" for these guys. Like a 10% battery bonus. i think it is safe to assume that Tesla will engineer the software limitation in a way that maximises battery life.

 

[yobigd20]

You know...as a reminder...it is April Fool's Day today. lol. although if this was a joke, I don't think many ppl would find it very funny haha

 

[132]

What I want to know is how this announcement will effect the financial forecasts. If only 4% had ordered the 40kw , I'm thinking the "average" profit per unit that many institutions were guesstamating is significantly too low.

 

[Al Sherman]

The only thing missing from this announcement was that the performance h/w is actually installed on the std 85 and can be enabled in the future! There was something there for the 40s and the 60s, but nothing here for us poor 85s! ;-)

Hmmm. Is the 900amp inverter the same? Just Firmware limited?

- - - Updated - - -

Well I'm confused. I'm one of the folks waiting to get my reservation in, sometime in the next 60 days :/ and from what I just heard and see in this thread, the 40kwh is no more? Correct? The 40kwh is the one I'm interested in. So, I have to cough up 10k more??

I'm sure it'll be clearer within your 60 day window but yes. That's pretty much the way I read it right now. Though, another way to look at it is; you haven't actually "coughed up" anything yet and the new info is that the entry level MS is 10k more than you originally thought.

- - - Updated - - -

It would be great Tesla eventually announces that all 3 versions of the car have identical mechanical components and the 40 & 60kwh owners can upgrade to 80kwh specs for a fee.

Yeah. And with that all purchasers get a free flight on Space X and a 2 week all inclusive stay at the Mars colony.

 

[Oyvind.H]

You know...as a reminder...it is April Fool's Day today. lol. although if this was a joke, I don't think many ppl would find it very funny haha

The press release is dated march 31st.

 

[wycolo]

+1 @TM.

They managed to turn this red headed step child into a collector's item.
--

 

[WarpedOne]

It would be great Tesla eventually announces that all 3 versions of the car have identical mechanical components and the 40 & 60kwh owners can upgrade to 80kwh specs for a fee.

No go, 60 kWh version IS ~160 pounds lighter than 85kWh versions.
Though they may offer a battery trade in program offering 85kWh to 60kWh owners at say $15k.

 

[Al Sherman]

I'm one of the 4% holding a 40kwh res and actually called Tesla last week to see if I can upgrade to a 60kwh just so i could get the car sooner. Am now thinking that my car will be delivered sooner and am also betting that Tesla will let me upgrade if I still wanted too. Will be getting the performance boost of a 60kwh but not the range if i keep the 40. Not sure if I should upgrade now. Guess it depends on how much the software change would cost to upgrade down the road.

Nobody responded so I'll take a shot. Seems to me this is a no brainer for anyone with a 40kWh reservation. DO NOT UPGRADE. At this point I don't think you'd get the car any sooner. At the very least, you're already getting the 60kWh pack, and increased performance with supercharging upgrade capability for nothing. If you are one of the few who have a 40kWH on order congrats. You're getting a great deal!

 

[ddruz]

Nobody responded so I'll take a shot. Seems to me this is a no brainer for anyone with a 40kWh reservation. DO NOT UPGRADE. At this point I don't think you'd get the car any sooner. At the very least, you're already getting the 60kWh pack, and increased performance with supercharging upgrade capability for nothing. If you are one of the few who have a 40kWH on order congrats. You're getting a great deal!

Absolutely agree. Anyone with a 40 kWh reservation is getting a great deal. You basically have a free option on a 60 kWh + SC at any point in the future and you may be able to charge in range mode all the time without concern about battery degradation.

 

[WarpedOne]

Tesla Motors site is back, 40 kWh option is still there with unchanged spec (less performance than 60 kWh).
Hmmm...

 

[NigelM]

Just woke up and catching up with all the night-owls, several thoughts occur:

• This is great for the people who order a 40kwh. They can still get the car they want but now with upgradeability.
• Tesla again uses unclear language; why use the word "cancelled" in the headline?
• There might be some minor upset for the small number of 40kwh reservation holders....until they hear the details.
• There's no reason why there should be a storm over this...depending on what they do with pricing.

(P.S. updated the thread title for clarity.)

 

[ItsNotAboutTheMoney]

Nobody responded so I'll take a shot. Seems to me this is a no brainer for anyone with a 40kWh reservation. DO NOT UPGRADE. At this point I don't think you'd get the car any sooner. At the very least, you're already getting the 60kWh pack, and increased performance with supercharging upgrade capability for nothing. If you are one of the few who have a 40kWH on order congrats. You're getting a great deal!

Does the 40kWh get the Supercharger hardware? They said they were putting the Supercharger hardware in all of the 60kWhs but did they mean that by battery or car model?

 

[markwj]

If they were to use the middle of the pack, what about vampire drain? Much more complex to manage SOC, when SOC can go negative.

My guess is they'll just use the bottom 2/3rds of the pack. Simple to stop charging at 40kWh equivalent,

 

[JRP3]

From capacity and weight difference we can deduce the cells are on the level of 300Wh/kg.

Except we know the cells are around 250Wh/kg, so the weight difference between the two does not accurately reflect only the cells.

I agree with those speculating that Tesla will use the top part and limit that pack at the bottom, not the top. Makes most sense from a cell balancing standpoint, as well as long term storage. So you still want to avoid a range charge in the "40kWh" pack. For pack longevity it would have been better to split the difference and use a middle range, but this way you still get the benefit of never reaching a low SOC.