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Are We Asking the Wrong Question About Charging?

If you live on the West Coast where chargers seem to be both more ubiquitous and more reliable than elsewhere in the U.S. and you want to understand why some people want to charge above 80%, you might want to watch this video. It's why I find EA's limiting charging at some stations to 85% to be condescending to the point of insulting and a serious case of denial about what their system is like to many EV owners.

 
ViperSSD said:
The 2 cycle test is definitely less $ but I also thought that it resulted in a lower rated range. At least, that has been the explanation on why the Taycans normally exceeds its rated range in tests pretty significantly.
Click to expand...
It does/did. I don't know about the new EPA calculations, but it resulting in a lower range is why manufacturers exceed the range, which is what makes it unrealistic. The 5-cycle EPA test tried to fix that by making it more realistic, but it went too far.

They will eventually find a middle ground (and maybe the new calculation methods already have, I don't know)
 
BS8899 said:
Also, if you look at the Lucid trims, the Pure and Touring have smaller batteries, but I don't understand why their charging time is as long as owners of these trims reported. I am not convinced it is a technical limiter.
Click to expand...
It is a technical limitation. The fewer the batteries, the lower the cumulative voltage, the lower the maximum charging speed. That's physics, not a conspiracy.
 
borski said:
It is a technical limitation. The fewer the batteries, the lower the cumulative voltage, the lower the maximum charging speed. That's physics, not a conspiracy.
Click to expand...
OK, I follow your physics argument RE: applicable charging Voltage and cumulative voltage vs battery string size I.e., the number of cells in a charging string). I agree with you that, if you only have one string of batteries, all in series, and if you cut the number of batteries by 1/3 (as in the case of AGT vs Pure/Touring), you cannot apply the same voltage to charge battery (e.g., the 900V architecture), That's your physics argument, correct?

But, how does the above premise affect the charging if we down-size the battery bank by 33%, as in the case of AGT vs the Pure/Touring ? Let's do a highly simplistic analysis:

[1] in a series connected string of Li-ion batteries, it takes ~240 (depending on the exact chemistry) in series to get to 900V. Obviously, the exact number of cells depends on the battery chemistry.
[2] If you charge this single string with a 900V supply, the same current flows through the entire string, correct?
[3] if you reduce the number of batteries in the string by 1/3 (as in the case of Pure/Touring) now, the string has ~160 batteries in series. You have to drop the voltage accordingly, say to ~600 volts. But the same current (as in the 900V longer string) flows through the shorter string.

Question: what is charging the battery, the current or the voltage? My understanding is the current charges the battery. The voltage is what is need to drive current through the string. The more batteries in the string, the higher the voltage required.

Under these conditions, why would the two strings (longer string vs shorter string) of batteries charge at different speed if the charging voltages are adjusted to fit the string sizes?

The Lucid Air has ~6,600 cells to make up its ~120 kWh capacity. Thus, it would require multiple strings in parallel, connected to the Wunderbox, correct?

If I cut the battery capacity by 1/3 (as the case of the Pure/Touring, say 4,400 cells), why can't one still maintain a 900V charging architecture and maintain the charging speed?

So, I am still puzzled, why this charging architecture is hampered in the Pure/Touring. I am trying to get educated. I am trying to understand whether there are actual physics limitations or it just take some engineering effort to rebalance the Pure/Touring battery bank topology and Wunderbox optimization. In other words, I don't follow why it is not possible to onboard energy from the DCFC at the same rate between the AGT and the Pure/Touring. If one could do that, the Pure/Touring should charge at a faster SoC replenishment rate (smaller battery) than the Air.

Welcome your insight.
 
Adnillien said:
I believe that OOS did test the 2025. I am curious about the improvement.
Click to expand...
There are many issues that do, or at least should, factor into one's decision to purchase an EV. Range, speed of charging, handling, power, size, cost, design and service are all basic issues. Then add in HUDs, buttons and switches vs "minimalist" interior design, luxury materials and finishes, ADAS features and implementation thereof, storage, audio systems, software systems, etc. etc.

IMO if one fixates on a single one or two of these factors one is missing the boat. One does need to do one's research and check out each of these but then one has to create a gestalt for the purchase that matches up with one's own needs and desires. And, IMO, that should also include an intangible if it applies (i.e., does it put a smile on your face when you start it up?). One doesn't need to have her choice top each category but for many it is sufficient to be competitive. For example, I don't track a car so I don't care if my 0-60 time is 2 seconds, 3 seconds or 4 seconds; but I do care that it is not => 6 seconds.
 
BS8899 said:
OK, I follow your physics argument RE: applicable charging Voltage and cumulative voltage vs battery string size I.e., the number of cells in a charging string). I agree with you that, if you only have one string of batteries, all in series, and if you cut the number of batteries by 1/3 (as in the case of AGT vs Pure/Touring), you cannot apply the same voltage to charge battery (e.g., the 900V architecture), That's your physics argument, correct?

But, how does the above premise affect the charging if we down-size the battery bank by 33%, as in the case of AGT vs the Pure/Touring ? Let's do a highly simplistic analysis:

[1] in a series connected string of Li-ion batteries, it takes ~240 (depending on the exact chemistry) in series to get to 900V. Obviously, the exact number of cells depends on the battery chemistry.
[2] If you charge this single string with a 900V supply, the same current flows through the entire string, correct?
[3] if you reduce the number of batteries in the string by 1/3 (as in the case of Pure/Touring) now, the string has ~160 batteries in series. You have to drop the voltage accordingly, say to ~600 volts. But the same current (as in the 900V longer string) flows through the shorter string.

Question: what is charging the battery, the current or the voltage? My understanding is the current charges the battery. The voltage is what is need to drive current through the string. The more batteries in the string, the higher the voltage required.

Under these conditions, why would the two strings (longer string vs shorter string) of batteries charge at different speed if the charging voltages are adjusted to fit the string sizes?

The Lucid Air has ~6,600 cells to make up its ~120 kWh capacity. Thus, it would require multiple strings in parallel, connected to the Wunderbox, correct?

If I cut the battery capacity by 1/3 (as the case of the Pure/Touring, say 4,400 cells), why can't one still maintain a 900V charging architecture and maintain the charging speed?

So, I am still puzzled, why this charging architecture is hampered in the Pure/Touring. I am trying to get educated. I am trying to understand whether there are actual physics limitations or it just take some engineering effort to rebalance the Pure/Touring battery bank topology and Wunderbox optimization. In other words, I don't follow why it is not possible to onboard energy from the DCFC at the same rate between the AGT and the Pure/Touring. If one could do that, the Pure/Touring should charge at a faster SoC replenishment rate (smaller battery) than the Air.

Welcome your insight.
Click to expand...
300 kw charging rate for AGT is
300,000w / 900v = 333.33 amps.
The same 300 kw charging rate for pure/touring would be 300,000w / 600v = 500 amps.

Batteries like being at 1 C for charging. You can boost it quicker by actively cooling the batteries. But amperage creates heat loss (amperage^2*Resistance).

AGT 118 kWh pack @ 500 amp has a C rate of:
500 amp / 118 kWh = 4.2 C
That same charge rate for Touring would be
500 amp / 92 kWh = 5.4 C

Would need a lot more active cooling to achieve the same charging rate for the reduced voltage of the Touring and Pure.

Having the Touring do the same C rate as GT
92 kWh * 4.2 C = 386 amp
386 amp * 600 volts = 231 kw charge rate
386 amp * 700 volts (closer approximation of Touring voltage) = 270 kw charge rate

The Toruing is 700+ volts and the ‘25 Pure is 650+ volts according to Lucid. Both are close in math. It appears Lucid is comfortable with the battery packs charging at approx 4.2 C for the given cooling system and battery chemistry. You can get into the weeds with each battery composition and its ability to go higher (LG vs Samsung).

The higher voltage allows for less current which creates less heat loss for achieving the same charging rate.
 
BS8899 said:
OK, I follow your physics argument RE: applicable charging Voltage and cumulative voltage vs battery string size I.e., the number of cells in a charging string). I agree with you that, if you only have one string of batteries, all in series, and if you cut the number of batteries by 1/3 (as in the case of AGT vs Pure/Touring), you cannot apply the same voltage to charge battery (e.g., the 900V architecture), That's your physics argument, correct?

But, how does the above premise affect the charging if we down-size the battery bank by 33%, as in the case of AGT vs the Pure/Touring ? Let's do a highly simplistic analysis:

[1] in a series connected string of Li-ion batteries, it takes ~240 (depending on the exact chemistry) in series to get to 900V. Obviously, the exact number of cells depends on the battery chemistry.
[2] If you charge this single string with a 900V supply, the same current flows through the entire string, correct?
[3] if you reduce the number of batteries in the string by 1/3 (as in the case of Pure/Touring) now, the string has ~160 batteries in series. You have to drop the voltage accordingly, say to ~600 volts. But the same current (as in the 900V longer string) flows through the shorter string.

Question: what is charging the battery, the current or the voltage? My understanding is the current charges the battery. The voltage is what is need to drive current through the string. The more batteries in the string, the higher the voltage required.

Under these conditions, why would the two strings (longer string vs shorter string) of batteries charge at different speed if the charging voltages are adjusted to fit the string sizes?

The Lucid Air has ~6,600 cells to make up its ~120 kWh capacity. Thus, it would require multiple strings in parallel, connected to the Wunderbox, correct?

If I cut the battery capacity by 1/3 (as the case of the Pure/Touring, say 4,400 cells), why can't one still maintain a 900V charging architecture and maintain the charging speed?

So, I am still puzzled, why this charging architecture is hampered in the Pure/Touring. I am trying to get educated. I am trying to understand whether there are actual physics limitations or it just take some engineering effort to rebalance the Pure/Touring battery ba k topology and Wunderbox optimization. In other words, I don't follow why it is not possible to onboard energy from the DCFC at the same rate between the AGT and the Pure/Touring. If one could do that, the Pure/Touring should charge at a faster SoC replenishment rate (smaller battery) than the Air.

Welcome your insight.
Click to expand...

All of this is way above my pay grade, but I do have one simple question. Why is your premise based on your statement that the Pure/Touring battery packs are 33% smaller than AGT's? Isn't the Pure AWD's 92 kWh pack at 78.0% (92/118) and the Pure RWD's 88 kWh at 74.6% (88/118)? Am I missing something?
 
Domo35 said:
300 kw charging rate for AGT is
300,000w / 900v = 333.33 amps.
The same 300 kw charging rate for pure/touring would be 300,000w / 600v = 500 amps.

Batteries like being at 1 C for charging. You can boost it quicker by actively cooling the batteries. But amperage creates heat loss (amperage^2*Resistance).

AGT 118 kWh pack @ 500 amp has a C rate of:
500 amp / 118 kWh = 4.2 C
That same charge rate for Touring would be
500 amp / 92 kWh = 5.4 C

Would need a lot more active cooling to achieve the same charging rate for the reduced voltage of the Touring and Pure.

Having the Touring do the same C rate as GT
92 kWh * 4.2 C = 386 amp
386 amp * 600 volts = 231 kw charge rate
386 amp * 700 volts (closer approximation of Touring voltage) = 270 kw charge rate

The Toruing is 700+ volts and the ‘25 Pure is 650+ volts according to Lucid. Both are close in math. It appears Lucid is comfortable with the battery packs charging at approx 4.2 C for the given cooling system and battery chemistry. You can get into the weeds with each battery composition and its ability to go higher (LG vs Samsung).

The higher voltage allows for less current which creates less heat loss for achieving the same charging rate.
Click to expand...
This is NOT correct. C rate is current/amp-hr capacity not current/kWhr capacity. At the same charging current, both the GT and Touring batteries have the same C-rate.
The GT has 30 parallel strings of 220 cells in series (22 modules with 30 parallel strings of 10 cells in series). Touring has 30 parallel strings of 180 cells. It is not easy to convert energy capacity (kWhr) to current capacity (amp-hour) because voltage varies as the cell is discharged. A reasonable estimate for current capacity is:

GT 112kWhr/3.6V/220 cells = .141 amp hr
Touring 92kWhr/3.6V/180 cells = .142 amp hr

Here we see that the current capacity is the same (within rounding error) because both have 30 parallel strings of cells.

Conclusion is that both GT and Touring will charge at the same current (amps), but Touring will charge at a lower power (kW) because of it lower voltage. They should take exactly the same time to charge from 10% to 80%.
 
Buffalo Bob said:
All of this is way above my pay grade, but I do have one simple question. Why is your premise based on your statement that the Pure/Touring battery packs are 33% smaller than AGT's? Isn't the Pure AWD's 92 kWh pack at 78.0% (92/118) and the Pure RWD's 88 kWh at 74.6% (88/118)? Am I missing something?
Click to expand...
You numbers for the Pure and Touring are, I think, the correct numbers. I was using a 1/3 reduction from the AGT battery size as a broad-stroke illustration of a smaller battery trim of the AGT. The way I phrased it might have come across as both the Pure and the Touring are the same and have a battery 33% smaller than the AGT. That wasn't the intent. I apologize for the muddled broad-stroke. That said, it does not change the point I was seeking clarity on....why do the Pure and Touring trims have lower charging rate than the AGT?
 
Adnillien said:
This is NOT correct. C rate is current/amp-hr capacity not current/kWhr capacity. At the same charging current, both the GT and Touring batteries have the same C-rate.
The GT has 30 parallel strings of 220 cells in series (22 modules with 30 parallel strings of 10 cells in series). Touring has 30 parallel strings of 180 cells. It is not easy to convert energy capacity (kWhr) to current capacity (amp-hour) because voltage varies as the cell is discharged. A reasonable estimate for current capacity is:

GT 112kWhr/3.6V/220 cells = .141 amp hr
Touring 92kWhr/3.6V/180 cells = .142 amp hr

Here we see that the current capacity is the same (within rounding error) because both have 30 parallel strings of cells.

Conclusion is that both GT and Touring will charge at the same current (amps), but Touring will charge at a lower power (kW) because of it lower voltage. They should take exactly the same time to charge from 10% to 80%.
Click to expand...
Thank you @Adnillen for the great insight!

Q: [1] Do Touring owners experience the same charge rate/charge time as the AGT?

[2] What is the reason for the Touring to have the same 30 banks of 180 cells? Is it to supply the necessary discharge current when driving? But the Touring and the Pure have lower power drive trains. Do they need the same current output from the batteries? For example, why can't the Touring (and Pure) maintain the 220 cell architecture as the AGT?
 
borski said:
These are worth watching:


Click to expand...
Yes, I have seen both videos. I also looked at the Wunderbox video very recently.

I was/am impressed by the knowledge of the Lucid executive and the technical capabilities of the hardware. That's in part why I am questioning why the Pure/Touring owners don't seem to realize the charging speeds they could/should experience. Having a smaller battery on these trims will compromise the range, that is a given. It is far less clear to me why the charging speed/charging time seem much lower than one would expect.
 
BS8899 said:
Thank you @Adnillen for the great insight!

Q: [1] Do Touring owners experience the same charge rate/charge time as the AGT?

[2] What is the reason for the Touring to have the same 30 banks of 180 cells? Is it to supply the necessary discharge current when driving? But the Touring and the Pure have lower power drive trains. Do they need the same current output from the batteries? For example, why can't the Touring (and Pure) maintain the 220 cell architecture as the AGT?
Click to expand...
All of the Air trims use the same modules (30 parallel strings of 10 cells). The difference is the number of modules put into a series string. GT has 22 modules. The touring eliminates the 4 modules in the rear seat footwell area lowering the rear seat floor and leaving 18 modules. I am not certain on the RWD Pure but I believe it has 16 modules. Lucid could have used 22 modules in all trims and used fewer parallel strings in the Touring/Pure but this would not allow the increased foot area in the Touring and Pure. It would also cost more and make the modules different between the trims.
 
borski said:
It does/did. I don't know about the new EPA calculations, but it resulting in a lower range is why manufacturers exceed the range, which is what makes it unrealistic. The 5-cycle EPA test tried to fix that by making it more realistic, but it went too far.

They will eventually find a middle ground (and maybe the new calculation methods already have, I don't know)
Click to expand...
I don’t know why you keep pcoming back to cost. We’re talking about multi-billion dollar companies. A one-time EPA test whether is $10k or $50k is comparing pennies. Germans are known for underrating everything, from hp, to torque, to acceleration numbers, and even to efficiency. Do you really think they would sacrifice an EPA rated 400 range over a few $k

The 5-cycle test back in 2022 was no more accurate. It was equally inaccurate but in the wrong direction. Sure…it’s improved since then, and now seems to match 70mph sustained driving more accurately, but this is still not real world.
 
Adnillien said:
All of the Air trims use the same modules (30 parallel strings of 10 cells). The difference is the number of modules put into a series string. GT has 22 modules. The touring eliminates the 4 modules in the rear seat footwell area lowering the rear seat floor and leaving 18 modules. I am not certain on the RWD Pure but I believe it has 16 modules. Lucid could have used 22 modules in all trims and used fewer parallel strings in the Touring/Pure but this would not allow the increased foot area in the Touring and Pure. It would also cost more and make the modules different between the trims.
Click to expand...
Thanks for the reply. And I understand the point RE: the hump on my AGT back seat area.

In your prior post, based on the battery configuration alone, since the Pure and Touring use the same battery modules, the Pure/Touring owners should experience the same charge speed as AGT, provided they are charged at the same voltage. Did I understand you correctly?

If so,.


do they (Pure and Touring owners) actually see that? If not, is the Wunderbox setting in these trims the limiting factor?
 
Adnillien said:
All of the Air trims use the same modules (30 parallel strings of 10 cells). The difference is the number of modules put into a series string. GT has 22 modules. The touring eliminates the 4 modules in the rear seat footwell area lowering the rear seat floor and leaving 18 modules. I am not certain on the RWD Pure but I believe it has 16 modules. Lucid could have used 22 modules in all trims and used fewer parallel strings in the Touring/Pure but this would not allow the increased foot area in the Touring and Pure. It would also cost more and make the modules different between the trims.
Click to expand...

...and from a marketing/sales perspective, no company would want their base model to have a greater range than their higher end trims.
 
Buffalo Bob said:
...and from a marketing/sales perspective, no company would want their base model to have a greater range than their higher end trims.
Click to expand...
We are not arguing the range. Lower ranges on the Touring/Pure are givens. The question is, is the charging rate compromised artificially.
 
BS8899 said:
In your prior post, based on the battery configuration alone, since the Pure and Touring use the same battery modules, the Pure/Touring owners should experience the same charge speed as AGT, provided they are charged at the same voltage. Did I understand you correctly?
Click to expand...
All three charge at the same current (amps) but a different voltage so the Touring/Pure charge at a lower power (kW). The smaller batteries require less energy to charge from 10% to 80% so the charging time is the same for 10% to 80% charge. The smaller batteries received less energy (power*time, kWhr) but same number of electrons since they charge at the same current.
 
BS8899 said:
We are not arguing the range. Lower ranges on the Touring/Pure are givens. The question is, is the charging rate compromised artificially.
Click to expand...
I understand that, but I was responding to @Adnillien's statement that: "Lucid could have used 22 modules in all trims and used fewer parallel strings in the Touring/Pure but this would not allow the increased foot area in the Touring and Pure. It would also cost more and make the modules different between the trims."

I think that making sure there was a significant range improvement between the lower end trims and the GT was Lucid's main objective, of course along with shoring up the gross margin of the lesser trim packages.

Here's some heresy as a side note... Removing the modules in such a way as to increase the rear legroom was a wonderful idea from a Pure/Touring customer satisfaction perspective, but I would argue that it was a questionable decision from a marketing perspective, as some people will buy one of the lower end trim packages just to get the extra legroom... despite sacrificing range and power in the process. Were it possible, I would have opted to keep the increased legroom in all models, and found some other place to put those extra modules in the GT. 'Were it possible' being the operative words.
 
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