Are We Asking the Wrong Question About Charging?

[Bill55]

I get your thinking, I just personally think it's actually less practical (just the way by brain works, no disrespect intended). Add 50kWh to a Hummer EV and add 50 kWh to an AGT...they mean totally different things in the real world. Yes, you can do the math yourself in your head, but how valuable is saying "I can add 50 kWh to my battery the fastest?" It's utterly useless if the car is inefficient and poorly designed. So probably some combination of the metrics of speed to charge -- based on kWh, NOT SOC and efficiency would be best.

Add 10 gallons of gas to an ICE Hummer and 10 gallons to a Honda Civic is also vastly different. No one talks about adding miles of Gas, because you don't buy miles, you buy gallons.
For an EV you buy kWhs. Most gas tanks don't show you number of gallons left is 1/2 tank.... so state of charge is very similar to principles people already understand.
With my driving I know I will get 3.5 miles for every 1 percent of charge. Making the math easy.

Coincidentally, I have a 2025 Sierra EV that gets 3.5 miles to 1 percent of charge. Of course each percent is 1.18kWh in the Air and 2.05kWh in the Sierra.

GM has done a very good job on the charging curve for the Sierra. Not sure how they are managing the dual pack, seems they are taking one pack very low. Even at 30% SOC I have pulled 350kW. 358kW from an EA charger if you can believe it and 150kW from 400V Tesla station.

On road trips I tend to start from home with 100 and then charge from 30-80. The Air is 20-30 minutes and the Sierra is 30-40 minutes.

Example for the Sierra 99kWh in 34 minutes. 32%-80%. 175 miles, but that's specific to my driving and my vehicle.

Wether it is an ICE or EV I know how far I can go on half a "tank", I know in my ICE truck I'm going to buy more gallons than in Corvette, and I'm going to buy more kWh in EV truck than the Air.

 

[momo3605]

Each module of 300 cells has 42V.

Dream/GT-P/GT:
42V per module x 22 modules = 924V

Touring/Pure:
42V per module x 18 modules = 756V

Because there are fewer modules in the lower trims (for weight, cost savings because batteries are expensive, the foot garage in the rear seats, and so on), the lower trims run at 756V, and the upper trims run at 924V.

It’s math, not conspiracy or marketing.

Please watch this:

(That should start at 14m 19s)

Yea I mean either way. 756V is still high. The IONIQ 5/6 does 20 min charges to 80% with an even smaller battery than the Pure, and the 350V teslas do 25 mins.

I really don’t understand why Lucid can’t hold at least 200kw to 50%. It is slower than all other 800V cars and mid-pack of the 400V cars

 

[Bill55]

Yea I mean either way. 756V is still high. The IONIQ 5/6 does 20 min charges to 80% with an even smaller battery than the Pure, and the 350V teslas do 25 mins.

I really don’t understand why Lucid can’t hold at least 200kw to 50%. It is slower than all other 800V cars and mid-pack of the 400V cars

Looking at a recent charge I got 70.7 kWh in 22 minutes 20-80% SOC. That’s an average of 192.8kW.
When the charger provides 100% of what the car asks for, it’s pretty good.

 

[momo3605]

Looking at a recent charge I got 70.7 kWh in 22 minutes 20-80% SOC. That’s an average of 192.8kW.
When the charger provides 100% of what the car asks for, it’s pretty good.

I love when DE/Sapphire owners pop right in to tell Pure/Touring owners that their experiences are wrong

 

[Bill55]

I love when DE/Sapphire owners pop right in to tell Pure/Touring owners that their experiences are wrong

I’ll make you a deal on the DE.

 

[BS8899]

Yes, all of this is fine. As both you and I separately advocated, the meaningful metrics are the bottomline numbers vis-a-viz,
>Range:

Yes, all of this is fine. As both you and I separately advocated, the meaningful metrics are the bottomline numbers vis-a-viz,

>Range: how far can the vehicle go before needing to be charged when I drive on highway s[eed (say 70-75mph)
>Charging Speed: how much time does it take to charge from 10% SoC to 80% SoC so I can get back on the road
>What Trim should I Buy:

As to what voltage the vehicle (i.e., the specific trim) charges at, the ordinary ownrer couldn't care less.

All of the deliberation and back-and-forth on charging voltage, charging curve, EPA-rating, EPA test cycles, are irrelevant to the most owners. It is nothing more than self-gratification for a bunch of geeks!

 

[BS8899]

I love when DE/Sapphire owners pop right in to tell Pure/Touring owners that their experiences are wrong

"Let them eat cake", said a famous French philosopher!

 

[BS8899]

First, much appreciate @Adnillien and other forum members for educating us in Lucid's battery module architecture, charging voltages, and the differences in the charging voltage and the resultant charging speeds etc.. To my understanding, the net/net of these dicussions boils down to: High Trims on the Lucid Air has 900+V charging. Lower trims (Pure/Touring) charge at a lower voltage (650V?), hence the slower charging speed and longer charge time, even though the batteries are smaller in the lower trims. It is postured as limited by physics.

All of that said, I am still a bit confused about some of the points advanced in the discussions describing the charging mechnism and topology.

Since i am a slow learning, let me try to outline my (mis)understanding. I am seeking your enlightment:

> @Adnillien said, a standard battery module in the Lucid consist of 220 cLi-ion battery ells. All lucid Air trims have the same modules. The high Trims have more modules and the low trims have fewer modules, correct?
Q: Are these 220 cells inside a battery module arranged in series or are they organized in a parrllel/series topolgy inside the module? Specifically, if the 220 cells are in series, their nominal voltage will be around 820V, but could be as high as 925V when fully charged, and as low as 550V when fully (mostly) discharged. Are these statements correct?

> Charging of the battery bank in the Lucid is under the control of the Wunderbox. Is this correct?
The Wunderbox sets the voltage/current to optimize the charging of the battery modules, correct?

> When charging the battery modules, the charge cycle goes through different phases, including a constant current phase and then a constnat voltage phase. Is this correct?

> Some forum users suggest that the battery modules are the same in all trim variants but the number of modules are different, hence the different achievable range of the trims. These all make sense. The question herein is not the difference in range of the different trims. The question pertains to the charging voltage, what is limiting it in the lower trims, and what is the resultant charging speed.

> Further, it was suggested that the charging topology involves having these battery modules connected in series. This topology, is used to explain that the lower trims, with fewer modules thus a shorter topology, must be charged at a lower voltage, leading to a slower charging speed. Am I interpreting it correctly?

If so:

> if the battery modules, being the same in all trims, each with 220 cells connected in SERIES, how can more than one module be connect IN SERIES to either 900V or 650V and still be effectively charged at high speed? Perhaps I am not undersatnding the charging topology.

> alternately, during the charging cycle, if each of the battery module have the charging voltage (900V or 650V) applied to them (i.e, no multiple modles connected in series), why is it necessary to charge the lower trims at a lower voltage? There is no question that charging at a lower voltage will result in a longer, perhaps much longer charge cycle. Thermal management was suggested by some, but it is not obvious indication why there would be a thermal problem charging a lower trim Lucid with a smaller battery, even when charged at 900V.

I'd be greatful for your enlightment.

 

[Adnillien]

> @Adnillien said, a standard battery module in the Lucid consist of 220 cLi-ion battery ells. All lucid Air trims have the same modules. The high Trims have more modules and the low trims have fewer modules, correct?
Q: Are these 220 cells inside a battery module arranged in series or are they organized in a parrllel/series topolgy inside the module? Specifically, if the 220 cells are in series, their nominal voltage will be around 820V, but could be as high as 925V when fully charged, and as low as 550V when fully (mostly) discharged. Are these statements correct?

Each module contains 300 cells; 30 parallel strings of 10 in series. The individual modules are the same between trims for GT/Touring/Pure.
- The GT has 22 modules in series to form the battery pack giving it 220 cells in series.
- The Touring has 18 modules in series to form the battery pack giving it 180 cells in series.
- I think the RWD Pure has 16 modules in series to form the battery pack giving it 160 cells in series. I am not positive on the Pure configuration

We don't have the datasheet for the cells used by Lucid but we do no the maximum (fully charged cell voltage is 4.2V. Typical Li-IoN NMC will have a voltage around 3.4V when fully discharged but this varies with cell chemistry so this is just an estimate.
- The GT battery pack voltage varies between 748V at 0% SOC to 924V at 100% SOC
- The Touring battery pack voltage varies between 612V at 0% SOC and 756V at 100% SOC
- The Pure RWD battery pack voltage varies between 544V at 0% SOC and 672V at 100% SOC

> Charging of the battery bank in the Lucid is under the control of the Wunderbox. Is this correct?
The Wunderbox sets the voltage/current to optimize the charging of the battery modules, correct?

Yes and the battery module BMS is providing the cell voltages and temperatures.

> When charging the battery modules, the charge cycle goes through different phases, including a constant current phase and then a constnat voltage phase. Is this correct?

This is typical for most solar applications that charge at a fairly slow rate. Given that the DC charging curves we see for Air show a linear decrease in current with SOC when DC fast charging, it seems the Lucid is trying to control current. For DC fast charging, the Air requests a voltage from the charger that achieves the desired current. There is not a straight forward answer to your question.

 

[BS8899]

Each module contains 300 cells; 30 parallel strings of 10 in series. The individual modules are the same between trims for GT/Touring/Pure.
- The GT has 22 modules in series to form the battery pack giving it 220 cells in series.
- The Touring has 18 modules in series to form the battery pack giving it 180 cells in series.
- I think the RWD Pure has 16 modules in series to form the battery pack giving it 160 cells in series. I am not positive on the Pure configuration

We don't have the datasheet for the cells used by Lucid but we do no the maximum (fully charged cell voltage is 4.2V. Typical Li-IoN NMC will have a voltage around 3.4V when fully discharged but this varies with cell chemistry so this is just an estimate.
- The GT battery pack voltage varies between 748V at 0% SOC to 924V at 100% SOC
- The Touring battery pack voltage varies between 612V at 0% SOC and 756V at 100% SOC
- The Pure RWD battery pack voltage varies between 544V at 0% SOC and 672V at 100% SOC



Yes and the battery module BMS is providing the cell voltages and temperatures.



This is typical for most solar applications that charge at a fairly slow rate. Given that the DC charging curves we see for Air show a linear decrease in current with SOC when DC fast charging, it seems the Lucid is trying to control current. For DC fast charging, the Air requests a voltage from the charger that achieves the desired current. There is not a straight forward answer to your question.

Thank you much for your clarification. It makes good sense (RE: the module constructs and the parallel/serial connections). Much appreciated!


Using the framework youprovideed above, Yes, the voltage applied to charge the smaller battery pack of the Pure/Turing needs to be reduced. But the individual cells in a 180 cell/18 module string CAN still be charged at the same electrical conditions as the GT's 22 module 220 cell strings, albeit the overall charging voltage is reduced, correct?

If so, why is the Touring/Pure charging substantially slower than the AGT?

 

[Adnillien]

Thank you much for your clarification. It makes good sense (RE: the module constructs and the parallel/serial connections). Much appreciated!


Using the framework youprovideed above, Yes, the voltage applied to charge the smaller battery pack of the Pure/Turing needs to be reduced. But the individual cells in a 180 cell/18 module string CAN still be charged at the same electrical conditions as the GT's 22 module 220 cell strings, albeit the overall charging voltage is reduced, correct?

If so, why is the Touring/Pure charging substantially slower than the AGT?

Yes the charging voltage is reduced for the Touring/Pure compared to the GT. All trims should all charge at the same current though. Take a mid SOC like 30%, the GT on a good day will charge at 198kW. At this SOC the cell voltage is somewhere near 3.6V, the pack voltage is 792V. Hence, the charge current is 250A.

The same conditions for the Touring and Pure
- The Touring pack voltage is (3.6V*180) or 648V. Hence, 250A at 648V is 162kW.
- The Pure RWD pack voltage is (3.6*160) or 576V. Hence, 250A at 576V is 144kW.

Yes the charging power is lower for the Touring/Pure than for the GT, but the charge current is the same. You can say that Touring/Pure charge slower (lower power) but the time it takes to charge to 80% SOC is still the same as the GT.

 

[BS8899]

Yes the charging voltage is reduced for the Touring/Pure compared to the GT. All trims should all charge at the same current though. Take a mid SOC like 30%, the GT on a good day will charge at 198kW. At this SOC the cell voltage is somewhere near 3.6V, the pack voltage is 792V. Hence, the charge current is 250A.

The same conditions for the Touring and Pure
- The Touring pack voltage is (3.6V*180) or 648V. Hence, 250A at 648V is 162kW.
- The Pure RWD pack voltage is (3.6*160) or 576V. Hence, 250A at 576V is 144kW.

Yes the charging power is lower for the Touring/Pure than for the GT, but the charge current is the same. You can say that Touring/Pure charge slower (lower power) but the time it takes to charge to 80% SOC is still the same as the GT.

Thank you so much for your great insights. I am in complete agreement with your framing. A scholar and a gentleman!

Part of the "controversy" or "mystery" here is why is the Touring/Pure appears to charge significantly slower. Some said Physics. But I don't see the Physics/Electrochemistry mechanisms that would explain the slower charging on the Pure/Touring.

Also, using your bullets above, it is more likely the owners will encounter chargers delivering 150kW than chargers delivering 200+kW. So, I'd expect the Touring/Oure to charge as fast as (if not faster) than the AGT. But , that's not the owners' experience.

Now, some might invoke the charging curves being different on the Pure/Touring. May be that is true. But why?

Base on your treatise above, the induvial cells in the battery pack on the AGT vs Pure/Touring are basically the same, or at least they can be the same. Hence, if properly configured and not limited by artificial means, should experience the same charging currents per cell. So, why is the Pure/Touring charging significantly slower on these lower trims?

 

[hydbob]

Thank you so much for your great insights. I am in complete agreement with your framing. A scholar and a gentleman!

Part of the "controversy" or "mystery" here is why is the Touring/Pure appears to charge significantly slower. Some said Physics. But I don't see the Physics/Electrochemistry mechanisms that would explain the slower charging on the Pure/Touring.

Also, using your bullets above, it is more likely the owners will encounter chargers delivering 150kW than chargers delivering 200+kW. So, I'd expect the Touring/Oure to charge as fast as (if not faster) than the AGT. But , that's not the owners' experience.

Now, some might invoke the charging curves being different on the Pure/Touring. May be that is true. But why?

Base on your treatise above, the induvial cells in the battery pack on the AGT vs Pure/Touring are basically the same, or at least they can be the same. Hence, if properly configured and not limited by artificial means, should experience the same charging currents per cell. So, why is the Pure/Touring charging significantly slower on these lower trims?

You keep saying you understand but keep asking the same question from @Adnillien. The Pure/Touring charge slower because they have less cells. That's it. That's all it's ever been. The rate is slower but the time to charge for % SOC is the same. There is no mystery or controversy.

 

[BS8899]

You keep saying you understand but keep asking the same question from @Adnillien. The Pure/Touring charge slower because they have less cells. That's it. That's all it's ever been. The rate is slower but the time to charge for % SOC is the same. There is no mystery or controversy.

"The Pure/Touring charge slower because they have less cells. That's it. That's all it's ever been. The rate is slower but the time to charge for % SOC is the same. "

Forgive my ignorance, your qutation above doesn't seem to make any sense to me based on Physic and Electrochemistry. I just don't get it!

Please point me to an authorative treatise so I can educate myself.

 

[borski]

"The Pure/Touring charge slower because they have less cells. That's it. That's all it's ever been. The rate is slower but the time to charge for % SOC is the same. "

Forgive my ignorance, your qutation above doesn't seem to make any sense to me based on Physic and Electrochemistry. I just don't get it!

Please point me to an authorative treatise so I can educate myself.

There have been plenty in this thread. I'm not entirely sure how to explain it clearer.

Have you watched both the Battery and Wunderbox tech talks? Peter explains the physics and math extremely clearly in the battery talk, Eric explains the Wunderbox very clearly in that talk, and @Adnillien has done a commendable job here trying to re-explain it a bunch of times too. I'm not trying to be dismissive, but I genuinely don't have another set of words through which to describe it.

 

[BS8899]

There have been plenty in this thread. I'm not entirely sure how to explain it clearer.

Have you watched both the Battery and Wunderbox tech talks? Peter explains the physics and math extremely clearly in the battery talk, Eric explains the Wunderbox very clearly in that talk, and @Adnillien has done a commendable job here trying to re-explain it a bunch of times too. I'm not trying to be dismissive, but I genuinely don't have another set of words through which to describe it.

I believe @Adnillien and I are on the same page, unless I totally misunderstood him.

AGTs' with a larger battery, more modules (22) thus longer strings, require a higher voltage to maximize the charging.
Pure/Touring have smaller batteries, less modules (18), require lower voltages to charge the smaller batteries. With the proper voltage, the cells in the Pure/Touring should charge at the same rate as in the AGT.

IF the Pure/Touring trims charge at the same rate at the optimal lower (lower than AGT's 900+V) voltage, then the charging time should be about the same. But are they? Stated differently, is the 600/650V setting the optimal one that allows the Pure/Touring to charge at the same rate as AGT? If not, why not?

The charge times reported by Pure/Touring owners seem to suggest the 600/650V might not be optimal.

Previouly, you suggested that the Pure/Touring charging voltage is set at 600V because it is limited by Physics. If you follow the exchange between Adnillien and me, we both think, if the correct voltage is applied to the Pure/Touring batteries, it should charge at the same RATE as the AGT battery @900+V.

 

[BS8899]

I believe @Adnillien and I are on the same page, unless I totally misunderstood him.

AGTs' with a larger battery, more modules (22) thus longer strings, require a higher voltage to maximize the charging.
Pure/Touring have smaller batteries, less modules (18), require lower voltages to charge the smaller batteries. With the proper voltage, the cells in the Pure/Touring should charge at the same rate as in the AGT.

IF the Pure/Touring trims charge at the same rate at the optimal lower (lower than AGT's 900+V) voltage, then the charging time should be about the same. But are they? Stated differently, is the 600/650V setting the optimal one that allows the Pure/Touring to charge at the same rate as AGT? If not, why not?

The charge times reported by Pure/Touring owners seem to suggest the 600/650V might not be optimal.

Previouly, you suggested that the Pure/Touring charging voltage is set at 600V because it is limited by Physics. If you follow the exchange between Adnillien and me, we both think, if the correct voltage is applied to the Pure/Touring batteries, it should charge at the same RATE as the AGT battery @900+V.

BTW, if you do the "Rule-of-Thumb" calculation, AGT with 22 modules charges ar 900V, then Pure/Touring with 18 modules should be charging around 900*(18/22) ~736V, not 600V!


The delta between 736V vs 600V could easily exaplin the slower charging rate on the Pure/Touring. Perhaps there are other limiters taht I am unaaware of. But is is not the charging physics or electrochemistry.

I am not trying to be an ass...but the numbers don't seem to jive!

 

[hydbob]

BTW, if you do the "Rule-of-Thumb" calculation, AGT with 22 modules charges ar 900V, then Pure/Touring with 18 modules should be charging around 900*(18/22) ~736V, not 600V!


The delta between 736V vs 600V could easily exaplin the slower charging rate on the Pure/Touring. Perhaps there are other limiters taht I am unaaware of. But is is not the charging physics or electrochemistry.

I am not trying to be an ass...but the numbers don't seem to jive!

Post in thread 'Are We Asking the Wrong Question About Charging?'
https://lucidowners.com/threads/are-we-asking-the-wrong-question-about-charging.10858/post-241489

 

[BS8899]

Yes, @Adnillien posted that, at a CELL voltage of 3.6V, the AGT charge voltage is ~800V. But that's ~30% SoC. Hence, to charge to 80% SoC and beyond, the cell voltage needed would be higher. I suspect that's why it is rated at "900+V". Stated differently, if the Touring/Pure charging is limited to 600V, it will take a long time, if ever, to get to say 80% SoC.

The question at hand is not weather the Turing or Pure will charge @600V. Of course it will...so would be AGT. But Pure/Touring owners seems to think their cars are taking 60min or more to get to 80% SoC.

 

[BS8899]

Let's ask the Pure and Touring Owners:

When you charge @ a DCFC (e.g., EA, EVGo, ertc.), how long does it take for you to charge from 10% to 30% SoC? How long does it take for you to charge from 10% SoC to 80% SoC?

Does your Lucid Pure/Touring meet your expectation regarding the charging speed at DCFCs?