Cybertruck Charging Curve (Recorded by Owner)

[JBee]

I'll just let chatgpt explain

Charging two 400V batteries in series versus in parallel leads to different outcomes in terms of voltage, capacity, and current demand. Here's a comparison:

### Charging in Series (to make 800V)
- **Voltage**: When two 400V batteries are connected in series, their voltages add up. So, you get an 800V system.
- **Capacity**: The capacity (measured in Ah or kWh) remains the same as one of the single batteries. It does not increase.
- **Current Demand**: The current demand for charging remains the same as for a single battery. However, the charger and system must be capable of handling the higher voltage (800V).
- **Benefits of 800V System**:
- **Faster Charging**: Higher voltage can support faster charging rates, reducing charge times.
- **Increased Efficiency**: Higher voltage systems can be more efficient, leading to less energy loss in the form of heat.
- **Lighter Wiring**: Higher voltage allows the use of thinner wires for the same power transmission, reducing weight.

### Charging in Parallel
- **Voltage**: The voltage remains at 400V, the same as a single battery.
- **Capacity**: The capacity doubles, offering increased energy storage (e.g., from 100Ah to 200Ah).
- **Current Demand**: The current demand for charging doubles if you want to charge at the same rate as a single battery, as now there is more capacity to fill.
- **Benefits**:
- **Increased Capacity**: More energy storage means longer use between charges.
- **Redundancy**: If one battery fails, the system can potentially still operate on the other.
- **Lower Voltage Handling**: The system and charger don’t need to handle higher voltages, which can simplify design and safety requirements.

### Summary
- **800V System**: Offers fast charging and efficiency, ideal for applications like electric vehicles where these factors are crucial.
- **Parallel System**: Provides more energy storage and redundancy, suitable for applications where extended usage time is more important than charging speed.

Each configuration has its own set of advantages and is chosen based on the specific requirements of the application. In the context of electric vehicles, the trend is moving towards higher voltage systems like 800V for their efficiency and fast charging capabilities.

____________________________________
Notice the part about charging times

Higher voltage charges faster. Because you wouldn't necessarily need to half the amps pushed. Resulting in higher wattage in

You are assuming that they would be adding the same amount of power both ways. But they wouldn't necessarily. I mean, what if they push the same amperage at the two voltages? Obviously the 800v charges faster right?

All of that misses the point however.

800V will increase the maximum charging rate that can be obtained through a charger and cable, but in no way is the dominate reason why batteries have an upper limit charge rate that reduces with increasing SOC.

The point here is simple in that batteries can only accept a limited amount of energy over a given time, so that as EM puts it, electrons can find their "parking spots". The emptier the parking lot, the faster it fills, because parking is easier to find. The fuller the less electrons can enter, because parking spots are harder to find, so less electrons can be pushed through at one time.

Now if those electrons were running at 800V or 400V is of no consequence for the batteries themselves, as each is cell is only 3.7V. Voltage does not increase the speed of electrons nor increase the amount of parking spots in the cell, so it has not meaningful use, except for, as above, increasing the charge rate capacity of the cables and charger to the vehicle.

If charger/cabling is not the limiting factor, it adds nothing to charge the vehicle.

But as shown in my post above, in the case of the CT 123kWh pack, the extra pack size, means that a v3 SC is limiting the maximum charge rate of the CT battery. In comparison, with a smaller pack, the MY is not being limited by v3 SC (well at least not much). So here a v4 would help, and as such the 800V/1kV would also help, as this will reduce cable size and heating losses.

Essentially, the battery in the CT is limiting factor with v4, but with v3 its the charger, until cell tapering occurs.

--

One side note here: 800V is however meaningful on the consumption side to reduce motor winding size and heat losses, so that's why they used 800V instead, like many other EV's have already.

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[Saygmo]

All of that misses the point however.

800V will increase the maximum charging rate that can be obtained through a charger and cable, but in no way is the dominate reason why batteries have an upper limit charge rate that reduces with increasing SOC.

The point here is simple in that batteries can only accept a limited amount of energy over a given time, so that as EM puts it, electrons can find their "parking spots". The emptier the parking lot, the faster it fills, because parking is easier to find. The fuller the less electrons can enter, because parking spots are harder to find, so less electrons can be pushed through at one time.

Now if those electrons were running at 800V or 400V is of no consequence for the batteries themselves, as each is cell is only 3.7V. Voltage does not increase the speed of electrons nor increase the amount of parking spots in the cell, so it has not meaningful use, except for, as above, increasing the charge rate capacity of the cables and charger to the vehicle.

If charger/cabling is not the limiting factor, it adds nothing to charge the vehicle.

But as shown in my post above, in the case of the CT 123kWh pack, the extra pack size, means that a v3 SC is limiting the maximum charge rate of the CT battery. In comparison, with a smaller pack, the MY is not being limited by v3 SC (well at least not much). So here a v4 would help, and as such the 800V/1kV would also help, as this will reduce cable size and heating losses.

Essentially, the battery in the CT is limiting factor with v4, but with v3 its the charger, until cell tapering occurs.

--

One side note here: 800V is however meaningful on the consumption side to reduce motor winding size and heat losses, so that's why they used 800V instead, like many other EV's have already.

Why we are excited to see a v4 charging curve, since v3 plus cybertruck is worse than rivian and has the same taper as a model s/x plaid, which means if falls off 250kw FAST. If it wasn’t the cells limiting the charge rate, regardless of 400v vs 800v charger, we should theoretically see the cybertruck sustain that max 250kw rate much longer than a model s/x.

 

[JBee]

Have we seen a V4 SC curve running at 800V? At 400V I expect the rate to be 250kW still.

I agree that it shouldn't taper as fast at 250kWh. But...it might be something as simple as the charger or the vehicle not yet being updated to accept the CT 123kWh pack. I'm not sure where Teslas manages the control of this for it's own vehicles, and might simply have a upper hard limit set on each charger that makes that profile, regardless of what tesla is plugged in or doing at the time.

 

[scottf200]

Exactly the same happened when the first 4680 Y's came out, but don't remember folks still freaking out about Model Y charge curves.

Yes, they did and still are ... this is a tech guy and has written a lot about it.
>>>
Branden Flasch who works in the charger industry has a Model Y 4680 and has been none-to-pleased with the charging.
<<<
Example Dec 23, 2023:

 

[terranx]

Why we are excited to see a v4 charging curve, since v3 plus cybertruck is worse than rivian and has the same taper as a model s/x plaid, which means if falls off 250kw FAST. If it wasn’t the cells limiting the charge rate, regardless of 400v vs 800v charger, we should theoretically see the cybertruck sustain that max 250kw rate much longer than a model s/x.

Plaid actually has the best charge curve of any Tesla right now

 

[Zoomit]

As well stated by @JBee, 800v charging does not significantly improve charging speed over 400v when the charge power is cell limited. I think that is what we're seeing now with the 4680 Cybercells in the Cybertruck for a majority of the charging curve. The reason why I think it's cell limited is that Tesla appears to be using basically the same charging profile (e.g. curve) as the 4680 Model Y AWD. The two curves look very similar when adjusted for pack size using C-rate as a reference.

If that is the case, I expect we'll see more real-world charging data that is similar to the Our Cyber Life video, though possibly with relatively minor improvements if low cell temps or station capacity were constraints. Just to state it again, this also means that 800v charging would not provide anything more than a very minor increase in charging performance, and only when started at very low SoC.

I created a charging model (overlayed gray dashed line below) based on the demonstrated Model Y 4680 charging power from Branden Flasch and extrapolated that to the CT pack size. Results are below.

Obviously I'm speculating, but until Tesla improves the charging curve, don't expect significantly faster charging than what's already been shown at either 400v or 800v stations.

 

[WHIZZARD OF OZ]

76% battery aka 93kW took over 50mins - charge to go from 14-90%

Of that 50mins only 19 of it was 250kwh - really low high charging speed for such a large battery

With current usage stats that is 50mins of charging for 143 mins of driving - aka a lot of travel time on a trip would be charging

All of that unfortunately aligns with data on charge times coming from other people posting info, which is not good.

Oh yea and this was with a preconditioned battery with outside weather of 73 F about perfect conditions......

It's obvious to me that the open tonneau and tailgate affected the dynamics of charging speeds. Moral to the story: Keep my Vault SHUT....._/

 

[WHIZZARD OF OZ]

Currently 5 V4 chargers in the US out of 2,000 superchargers? So super available

Albury on the border between NSW and Victoria have the first V4 in Oz. Total around 14.....✓

 

[RVAC]

Not really buying that excuse as they have had 4680 in TMYs for a while and certainly have a ton of data on charging them. I would have expected better especially with Tesla knowing how the CT would be compared the existing EV trucks out there (Rivian, F150 lightning)

Rivian comparison:

Agree, precedent with 4680 MY does not inspire confidence, charging curve has yet to improve on that and we're almost two years in. This could seriously dampen demand, you can't have both range and charging be underwhelming.

At this point it basically matches the model x and model s plaid charge curve. Not great for having an additional 25kwh battery size in their newest flagship product, and consuming what, 30% more energy? I really miss that 500mile range that was promised. Even an additional 20-30kwh under the bed would give it that much better charge curve without sacrificing highway range much at all ?

It's way off S/X refresh, those hold 250kW to over 30%.

Even funnier is that we are looking at the charge curve for a limited production as if it will remain static for all time and never ever change, while ignoring that Tesla can and will change it based on what is learned from customer charge sessions and all those extra BMS data now being collected.
Exactly the same happened when the first 4680 Y's came out, but don't remember folks still freaking out about Model Y charge curves.

Yeah and the curve is still the same (read: poor) on those MYs. We're talking about significant changes, not minor adjustments.

 

[AlDente]

The CT's BMS is a work in progress so no strong inference can be drawn from this Thread.

 

[scottf200]

The new 5 passenger KIA EV6 [url] was put in these charts as well.

kW charging power

C-Rate

 

[Zoomit]

If that is the case, I expect we'll see more real-world charging data that is similar to the Our Cyber Life video, though possibly with relatively minor improvements if low cell temps or station capacity were constraints. Just to state it again, this also means that 800v charging would not provide anything more than a very minor increase in charging performance, and only when started at very low SoC.

Here're updated graphs with Ryan Shaw's charging data from his YouTube review (at 11:00).

Both these charging sessions overlap remarkably well. Therefore,

1. This builds my confidence that this charge curve represents an optimal charge session for today's hardware and software configuration.
2. The current Gen 2.3 cell charge curve c-rate is less than the Gen 1 curve from the Model Y AWD.
3. My speculative V3 and V4 charge curves as shown are likely too optimistic.
4. This lends credance to my theory that the battery thermal management system has a lot of untapped potential and can support much higher charge power.

 

[Gigahorse]

So after a lot of people dismissed the early charging data, out of spec has done a full breakdown and review, of an hour long video with a ton of data points but the TLDR is.

The charging curve and therefore charging time of the CT is really bad and becomes brutal if you are forced to use a V2 supercharger which are the most common.
With the limited range this could be a major issue with the CT if not fixed with software soon.

Out of spec charging data update, charge speeds are really slow unfortunately.
Overall out of spec charge review was "poor" for charging
"This is the worst part of the cybertruck"
"this makes cybertruck a tough sell"

 

[Gurule92]

So after a lot of people dismissed the early charging data, out of spec has done a full breakdown and review, of an hour long video with a ton of data points but the TLDR is.

The charging curve and therefore charging time of the CT is really bad and becomes brutal if you are forced to use a V2 supercharger which are the most common.
With the limited range this could be a major issue with the CT if not fixed with software soon.

Out of spec charging data update, charge speeds are really slow unfortunately.
Overall out of spec charge review was "poor" for charging
"This is the worst part of the cybertruck"
"this makes cybertruck a tough sell"

So I went to go watch the video. And in the first 1:26 seconds, Kyle asks Ryan to rate it. Thumbs up or down. He literally gives a thumbs middle.

That's definitely not class leading but it could be worse. Still watching.

"Sitting there at the charger, it almost felt worse and more annoying then what the data is suggesting."

 

[Gigahorse]

So I went to go watch the video. And in the first 1:26 seconds, Kyle asks Ryan to rate it. Thumbs up or down. He literally gives a thumbs middle.

That's definitely not class leading but it could be worse. Still watching.

"Sitting there at the charger, it almost felt worse and more annoying then what the data is suggesting."

It is a LONG video, but worth the watch.
Ryan gives it a thumbs middle, Kyle gives it a "this makes cybertruck a tough sell"

I HOPE that the curve can be fixed within the next week or two with software, because towards their summary of the CT charging you will hear the final verdicts of....

"This is the worst part of the cybertruck"
"this makes cybertruck a tough sell"
- Out of spec

Which, not gonna lie, really sucks. Was hoping that coming in with a very low state of charge, battery preconditioned etc could get better #s that the early ones we were seeing

Their quotes/buzzwords aside, all you have to do is look at the chart and see the rates between 30-80% to get depressed. Those %s are where most of the charging is done, as below 10% is risking getting stranded and above 90% is bad for the battery and SLOW

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