[Rumor] Significant Engineering Issues with Model 3

[JeffK]

I might be missing something here as I haven't read the entire thread, but surely that original quote referred to ORDERS being placed not CARS being produced?

This is true, it was an assumption made by many that these were also their goals.

As we all know when Tesla buys parts they owe money, that money is generally paid when goods are sold. A slower ramp up means they have more parts on hand and it is therefore riskier to the business.

 

[Dangerous Fish]

True, but some of that risk is offset by the reservation money and I suspect those estimates of order quantities had some contingency built in and contractual terms which minimised the risk.

In any case, Musk is not exactly risk-averse, is he?

 

[KarenRei]

I agree, we will likely get the same charger for both battery pack model 3s However, we know for certain that there will be at least two battery packs

Not at launch we don't.

Rumors are saying the larger of the two packs will be available first.

The charger on the 100 kWh model is provides more power with 72 Amps and therefore faster charging than the 75 kWh's 48 amp charger.

75kWh is "it could ship with that much at some point". By that point you really think Model S will still only max out at 100kWh? You really think they'll let the Model 3 outrange the Model S (which would happen at 75kWh)? Not a chance of that.

Model 3 is just a smaller, more affordable version of Model S w less range & power & fewer features." -- Elon Musk

The concept of a 75kWh pack came from this tweet (in addition to overinterpreting a photo taken from an RC):

"The shorter wheelbase only allows for a 75 kWh pack in Model 3 at current cell/module energy densities" -- Elon Musk

Interpreting that as "It will not only be available at launch, but may be the only option" is just silly.

The vehicle was promoted as having a range of at least 215mi. Thinking that it's going to launch with potentially 350mi range as the only option is silly. They will never let Model 3 outperform or outrange S. They might make addons that allow enhanced Model 3 performance to exceed baseline Model S performance, and enhanced model 3 range to exceed baseline Model S range - but they're not going to let the baseline or enhanced versions ever beat (or approach) their higher-end equivalents. Standard practice in the automotive world; you have to have a selling point for your higher-end vehicles if you want to upsell.

 

[JeffK]

Not at launch we don't.





75kWh is "it could ship with that much at some point". By that point you really think Model S will still only max out at 100kWh? You really think they'll let the Model 3 outrange the Model S (which would happen at 75kWh)? Not a chance of that.



The concept of a 75kWh pack came from this tweet (in addition to overinterpreting a photo taken from an RC):



Interpreting that as "It will not only be available at launch, but may be the only option" is just silly.

The vehicle was promoted as having a range of at least 215mi. Thinking that it's going to launch with potentially 350mi range as the only option is silly. They will never let Model 3 outperform or outrange S. They might make addons that allow enhanced Model 3 performance to exceed baseline Model S performance, and enhanced model 3 range to exceed baseline Model S range - but they're not going to let the baseline or enhanced versions ever beat (or approach) their higher-end equivalents. Standard practice in the automotive world; you have to have a selling point for your higher-end vehicles if you want to upsell.

You are starting to resort to strawman arguments and putting words in my mouth.

The 74/75 kWh reference comes from other sources. The notion that the larger battery pack will be available from the beginning is from Trevor Page who heard it from a source. This is why I qualified them as rumors, what I actually think is irrelevant.

As for a 75 kWh Model 3 having a greater range than a 75 kWh Model S. This is basic physics.

 

[KarenRei]

You are starting to resort to strawman arguments and putting words in my mouth.

No, I'm taking words from Elon Musk's mouth.

As for a 75 kWh Model 3 having a greater range than a 75 kWh Model S. This is basic physics.

Right, comparing the highest-possible range Model 3 variant at some point in the future to the lowest-range Model S version at present is totally a fair comparison.

I'll repeat:

. They may at some point offer a larger pack variant, but it will almost certainly ship with the same max-current onboard charging as the base Model 3, whose pack will be in the ballpark of 50kWh, maybe a little more. Just like 100kWh Model Ss ship with the same max-current onboard charging as 75kWh ones.

1) They will not let Model 3 exceed Model S in range. It'd be stupid, and also in contradiction of what Musk claimed.
2) When comparing chargers, you should compare the baseline models of both vehicles, not mix-and-match.
3) When comparing future options, you should compare to future options on both 3 and S, not just 3-future with S-present.

A 48A charger on a ~50kWh pack (baseline Model 3) is equivalent to a 72A charger on a ~75kWh pack (baseline Model S).

 

[JeffK]

1) They will not let Model 3 exceed Model S in range. It'd be stupid, and also in contradiction of what Musk claimed.
2) When comparing chargers, you should compare the baseline models of both vehicles, not mix-and-match.
3) When comparing future options, you should compare to future options on both 3 and S, not just 3-future with S-present.

You're starting to mix up power and energy

1. Can you cite anywhere that Elon has said that the highest range Model 3 won't have a higher range then all Model S versions not just the 100D? The high end Model 3 will have more range than any existing Model S 60 or 75 kWh.

2. Base Model S and likely all versions of Model 3 have a 48 amp charger.

3. See number 2 and compare apples to apples. A future or current 75 kWh Model 3 would take the same amount of energy as a 75 kWh Model S (ignoring charging energy losses of course). This is an undeniable fact. You can't find a way around it. If you are measuring by miles per minute then, yes, the model 3 would charge faster due to it's more efficient usage.

 

[ModelNforNerd]

They will not let Model 3 exceed Model S in range. It'd be stupid, and also in contradiction of what Musk claimed.

So here's where I'm going to disagree with you.......


from a bottomline standpoint, which is better for Tesla right now?

If I check all the boxes on a Model 3 P75D-L that gets as much range as the (now) base Model S? or if I buy a barebones S?


The margin they're going to make from selling me a maxed out 3 is more than they would make selling me a "stripper" Model S.


At the top end of the Model 3, there will be some overlap with the S.

 

[scaesare]

A 48A charger on a ~50kWh pack (baseline Model 3) is equivalent to a 72A charger on a ~75kWh pack (baseline Model S).

Not quite. When it comes to total time to completely charge the pack, they are similar.

But when it comes to total energy delivered per unit of time, no.

An example of where this matters:

On short notice I need to make a 150-mile round trip this afternoon. I currently only have only about 50 miles of range left in my pack after this morning's driving. Either battery size is capable of the journey. However:

- The 72A charger will add 100 miles of range in about 85 minutes.

- The 48A charger will add 100 miles of range in about 2 hours and 10 minutes

So despite the ratio of charger power to battery size being the same, your fast turnaround trip will require you to wait 45 minutes longer in this example.

 

[malcolm]

The Charger......it's significant!

There are.......issues.

Possibly engineering in nature.

Because.....reasons.


Summary: All engineering projects/products have engineering issues*

*from the Engineering College of No Duh!

 

[KarenRei]

- The 72A charger will add 100 miles of range in about 85 minutes.

- The 48A charger will add 100 miles of range in about 2 hours and 10 minutes

No, and now we're back to my original post. Musk's stated Cd target for Model 3 is 0.21, which is 87,5% that of Model S, while it's a smaller vehicle, aka smaller cross section. So CdA is significantly smaller in Model 3, perhaps 75% (if 93% as long on each axis), maybe less (90% as long on each axis = 71% CdA; 87% as long on each axis = 66% CdA; etc). It's also likely hundreds of kilograms lighter (smaller pack, smaller footprint - despite using a mix of steel and aluminum), and if anything the tires look even lower Crr. And even parasitic draws should be lower (e.g. heating and cooling needs are proportional to surface area). The simple fact is, Model 3 - by its very design principles to minimize battery size/cost without making range unacceptable - uses less energy per km, aka gets more range per kWh of charging. If it uses, say, 67% as much energy per mile, then 48A adds 100 miles of range in exactly the same length of time as 72A on Model S. If it uses 75% as much energy, it's only a 12% difference. 80% energy consumption is a 20% difference.

 

[scaesare]

No, and now we're back to my original post. Musk's stated Cd target for Model 3 is 0.21, which is 87,5% that of Model S, while it's a smaller vehicle, aka smaller cross section. So CdA is significantly smaller in Model 3, perhaps 75% (if 93% as long on each axis), maybe less (90% as long on each axis = 71% CdA; 87% as long on each axis = 66% CdA; etc). It's also likely hundreds of kilograms lighter (smaller pack, smaller footprint - despite using a mix of steel and aluminum), and if anything the tires look even lower Crr. And even parasitic draws should be lower (e.g. heating and cooling needs are proportional to surface area). The simple fact is, Model 3 - by its very design principles to minimize battery size/cost without making range unacceptable - uses less energy per km, aka gets more range per kWh of charging. If it uses, say, 67% as much energy per mile, then 48A adds 100 miles of range in exactly the same length of time as 72A on Model S. If it uses 75% as much energy, it's only a 12% difference. 80% energy consumption is a 20% difference.

Given that a the Model 3 could have a 75kW pack as well, this doesn't hold true. Both my example calculations use the same 250Wh/mile factor... in other words assuming the same Model 3 chassis.

 

[MartinAustin]

No, and now we're back to my original post. Musk's stated Cd target for Model 3 is 0.21, which is 87,5% that of Model S, while it's a smaller vehicle, aka smaller cross section. So CdA is significantly smaller in Model 3, perhaps 75% (if 93% as long on each axis), maybe less (90% as long on each axis = 71% CdA; 87% as long on each axis = 66% CdA; etc). It's also likely hundreds of kilograms lighter (smaller pack, smaller footprint - despite using a mix of steel and aluminum), and if anything the tires look even lower Crr. And even parasitic draws should be lower (e.g. heating and cooling needs are proportional to surface area). The simple fact is, Model 3 - by its very design principles to minimize battery size/cost without making range unacceptable - uses less energy per km, aka gets more range per kWh of charging. If it uses, say, 67% as much energy per mile, then 48A adds 100 miles of range in exactly the same length of time as 72A on Model S. If it uses 75% as much energy, it's only a 12% difference. 80% energy consumption is a 20% difference.

Couldn't agree more, and we can look to the combustion engine marketplace to see the contrasts. Smaller cars often have range that belies their small size. Range is not really a premium aspect of more expensive cars. Fuel stations are commonplace and owners don't mind filling up often in cars with short range. You don't necessarily get longer range in a BMW 7 compared to smaller cars. You often get more interior space, luxury and comfort. Nobody talks about the range of a Mercedes S550, but it's one of the first things people ask about on a Tesla Model S.

These differences are partly due to the incredibly inefficient nature of the ICE. Physics is not the principal factor in play.

An ICE vehicle equipped with a 25-US-gallon tank is carrying around 850kWh of energy! Only because the engine is so inefficient do we see a range of (say) 500 miles.

With electric cars, energy capacity is currently quite small (e.g. "only" 85kWh), and even though the powertrain is so energy-efficient that basic physics plays a major role, and there is no escaping its grasp. The range of an electric car is quite easy to gauge based on easily-discernable properties such as weight, size and aerodynamic shape.

For this reason, a small Tesla has a very good chance of travelling further than a larger Tesla, if they have the same battery capacity. Since the same company is making the powertrain in both, we can't say the engineering teams are different and one car is significantly different to the other.

So we should be expecting to see a number a lot higher than the 215 previously mentioned - for the exact reasons KarenRei states. Smaller size, narrower tires etc.

 

[JeffK]

f it uses, say, 67% as much energy per mile, then 48A adds 100 miles of range in exactly the same length of time as 72A on Model S.

True, (assuming you have a P100D with a 72 amp onboard charger instead of a Model S 75)
However, let's make it clear that if charging a Model S and a Model 3 to 75 kWh and with both having 48 amp onboard chargers, it charges 75 kWh in the same amount of time just as filling a 10 gallon tank on a sports car fills up just as fast as a 10 gallon tank on a hybrid.

Saying the hybrid fills up faster than a sports car because it gets more miles per minute is pretty strange. It's probably more correct to say they fill at the same speed but the hybrid can gain more range in a given amount of time or more range per gallon.

 

[AnxietyRanger]

I might be missing something here as I haven't read the entire thread, but surely that original quote referred to ORDERS being placed not CARS being produced?

In any case, I echo what's being said by some here. We've only got a few more days to wait until we know a lot more about the final specs. and production capacity so why not just have a coffee and wait to hear the facts?

We are analyzing the trustworthiness of a source that posted in April (the OP). I find the launch quite irrelevant to that, though I welcome new data from the launch of course in that analysis.

 

[KarenRei]

However, let's make it clear that if charging a Model S and a Model 3 to 75 kWh

Now we're back to comparing a base model with a theoretical fully upgraded model and ignoring that both bases and upgrades will share a common charger, and thus upgrades will always take longer to reach their max than the base versions. Is there some reason that we're engaging in circular conversations here?

 

[KarenRei]

You're starting to mix up power and energy

1. Can you cite anywhere that Elon has said that the highest range Model 3 won't have a higher range then all Model S versions not just the 100D?

I assume you mean "any", not "all". And that topic is irrelevant because you don't compare base versions to upgrades.

2. Base Model S and likely all versions of Model 3 have a 48 amp charger.

That just makes the comparison worse for the S by increasing the length of charge time in some versions. Comparing to 72A was being generous.

3. See number 2 and compare apples to apples. A future or current 75 kWh Model 3 would take the same amount of energy as a 75 kWh Model S

And apparently that's all we ever do here, compare hypothetical fully-range-upgraded versions to minimum-range existing versions. I'm out of this thread, this is such a waste of time.

 

[diamond.g]

I assume you mean "any", not "all". And that topic is irrelevant because you don't compare base versions to upgrades.



That just makes the comparison worse for the S by increasing the length of charge time in some versions. Comparing to 72A was being generous.



And apparently that's all we ever do here, compare hypothetical fully-range-upgraded versions to minimum-range existing versions. I'm out of this thread, this is such a waste of time.

To be honest that is probably part of the reason Tesla dropped the MS60, because it only offered a mere 3 more miles of range over the base Model 3. The gap wasn't big enough for base models.

 

[Jayc]

One thing I have understood is that Tesla doesn't really have a fixed long-term strategy regards to differentiating S and 3. However at any given point in time, they do seem to differentiate the two in ways they can - this is already clear. Going forward I expect the same story to continue which means for those who can afford it, Model S will always offer MORE.

I highlighted the word 'more' because in my view, it means more luxury and features taken collectively i.e. more overall and not (necessarily) more of every feature.

 

[ZeApelido]

Anywho, I don't know for sure that the rumored 48 amp limit is due to this engineering issue. Maybe they fixed the issue but limited it on purpose to differentiate from Model S/X. I haven't seen this friend in months and only would ask when I see him in person about it. Probably not too important at this point.

Amusing to see the variety of responses to actually providing real "inside" information, which is relatively rare. You would think that would be looked at positively!

 

[diamond.g]

Anywho, I don't know for sure that the rumored 48 amp limit is due to this engineering issue. Maybe they fixed the issue but limited it on purpose to differentiate from Model S/X. I haven't seen this friend in months and only would ask when I see him in person about it. Probably not too important at this point.

Amusing to see the variety of responses to actually providing real "inside" information, which is relatively rare. You would think that would be looked at positively!

Really I am not sure why folks are so against having a bigger onboard AC charger if possible. All it adds are possibilities for destination charging, especially in places where SuperCharging isn't available (looking at you Outer Banks).