Cybertruck will be 800V

[GregD60]

Thank you for that. From what I had seen they did not include it but I must have misunderstood or it was incorrect information.

Do you know if it has a 12V system at all? Curious if it has no 12V bus, or if it has 12,48, and 800V.

Either way, more accessories at 48V is nice. Hopefully they have eliminated the 12V bus and run everything off the 48V to kickstart the transition.

I haven't seen any mention of a 12V cigarette outlet which would seem to be a significant miss, since there are still many car accessories that use that to power them. You wouldn't need a whole bus, just a small DC/DC converter to step the voltage down for one or two connections. The computers and USB ports don't run on 48V, so there are obviously some power supplies to feed them. USB ports are typically 5V.

48V to 12V converters are readily available. With a quick search, I found one rated at 240 watts for $24. Then you just have to find the right spot to tie into the 48V system. Hopefully, Tesla makes this not too difficult. If I were Tesla, I'd just make this standard on the vehicle, and install both a cigarette lighter outlet and and a couple of spade connectors to tap into. But I'm not Elon.

 

[JulienW]

It's required for steer-by-wire, all this new tech is really putting a strain on the voltage, so it was time to move up.

Yea this has 3 motors (LF, RF and Rear) and requires up to nearly 4kW. That would be over 300A@12V. Now that would require some heavy cabling.

Also the 12V system was implemented in the 50s from 6V when car's started added accessories over the standard starter and lights. Just think how many more 12V uses there are today. The amount of current required to move this amount of power around at 12V is nearly astronomical. We should have started moving to 48V 25 years ago. Hope to see all newly designed cars move to this so all the OEM's will start make the parts.

 

[terranx]

I haven't seen any mention of a 12V cigarette outlet which would seem to be a significant miss, since there are still many car accessories that use that to power them. You wouldn't need a whole bus, just a small DC/DC converter to step the voltage down for one or two connections. The computers and USB ports don't run on 48V, so there are obviously some power supplies to feed them. USB ports are typically 5V.

48V to 12V converters are readily available. With a quick search, I found one rated at 240 watts for $24. Then you just have to find the right spot to tie into the 48V system. Hopefully, Tesla makes this not too difficult. If I were Tesla, I'd just make this standard on the vehicle, and install both a cigarette lighter outlet and and a couple of spade connectors to tap into. But I'm not Elon.

If this is an issue, you can get 12v out of the usb-c ports, which should be good for 3A. Could probably use something like this https://www.amazon.com/GutReise-12-...refix=usb-c+pd+to+12v+adapter,aps,139&sr=8-23

 

[Nack]

I haven't seen any mention of a 12V cigarette outlet which would seem to be a significant miss, since there are still many car accessories that use that to power them. You wouldn't need a whole bus, just a small DC/DC converter to step the voltage down for one or two connections. The computers and USB ports don't run on 48V, so there are obviously some power supplies to feed them. USB ports are typically 5V.

48V to 12V converters are readily available. With a quick search, I found one rated at 240 watts for $24. Then you just have to find the right spot to tie into the 48V system. Hopefully, Tesla makes this not too difficult. If I were Tesla, I'd just make this standard on the vehicle, and install both a cigarette lighter outlet and and a couple of spade connectors to tap into. But I'm not Elon.

Yeah, that's always been the problem with 42V back in the late 90s and early 2000s and with 48V now. You can run a lot off 48V, but you still need a 12V bus for some things due to legacy components. If you need a 48V AND 12V then 48V just starts adding a lot of complexity and cost for minimal benefit. I was curious how Tesla was going to overcome this issue as its what is holding every other automaker back. I was really hoping they would go for it though as they are kind of the industry trend setters, and it would spark a lot of accessories that would convert the 48V to 12V or give a roadmap of how to do it.

The DC/DC converters obviously work, but they also have a high fail rate so they are generally shied away from for anything that is needed for safety. In this case they could make 48V the main bus which powers most everything and ECUs, and use a DC/DC for the 12V accessory bus so if your DC/DC crapped out you would only be out some accessories Either that or you just build the DC/DC into the board for the 12V accessory similar to how it works for supplying various voltages for USB plugs, etc.

This isn't my area (Electrical engineering) but I have been around the conversations for a while trying to determine cost/benefit for using higher voltage levels in commercial vehicles from a system perspective.

Interestingly the 48V was chosen over the initially proposed 42V to help the transition as it did not require a special battery. A lot of 48V systems and 24V systems (European commercial trucks) are just multiple 12V batteries in series to remove the requirement for unique batteries. Many 48V accessory systems work similar to the battery pack in the Hummer EV where they are connected in parallel when charging from the 12V system alternator and switched to series connection when there is a needed draw (which does not happen while charging in these cases obviously).

 

[GregD60]

If this is an issue, you can get 12v out of the usb-c ports, which should be good for 3A. Could probably use something like this https://www.amazon.com/GutReise-12-15V-Cigarettes-Lighter-Converter/dp/B0BYCLYN4Y/ref=mp_s_a_1_23?crid=ZVATY8PTMFZW&keywords=usb-c+pd+to+12v+adapter&qid=1701777915&sprefix=usb-c+pd+to+12v+adapter,aps,139&sr=8-23

That would be fine for low powered things, but what about something like a tire inflator that needs 10A? Actually, the Cybertruck has a big compressor and air pressure tank built in for the suspension. It would be nice if that could just be used to inflate the tires, but I haven't heard any mention of such a capability. Instead, I see where there is a Cybertruck Air Compressor Ultra in the Tesla accessories shop for $550. That's a bit much for something to inflate the tires. Since the Cybertruck has 120V outlets, I guess we can just pick up a 120V inflator, maybe something like this for $20, and an extension cord.

 

[terranx]

That would be fine for low powered things, but what about something like a tire inflator that needs 10A? Actually, the Cybertruck has a big compressor and air pressure tank built in for the suspension. It would be nice if that could just be used to inflate the tires, but I haven't heard any mention of such a capability. Instead, I see where there is a Cybertruck Air Compressor Ultra in the Tesla accessories shop for $550. That's a bit much for something to inflate the tires. Since the Cybertruck has 120V outlets, I guess we can just pick up a 120V inflator, maybe something like this for $20, and an extension cord.

I actually forgot about the 120v outlets. You could probably get a 120v to 12v inverter and run whatever you need off that. Looks like you can get those pretty cheap too

 

[GregD60]

Yeah, that's always been the problem with 42V back in the late 90s and early 2000s and with 48V now. You can run a lot off 48V, but you still need a 12V bus for some things due to legacy components. If you need a 48V AND 12V then 48V just starts adding a lot of complexity and cost for minimal benefit. I was curious how Tesla was going to overcome this issue as its what is holding every other automaker back. I was really hoping they would go for it though as they are kind of the industry trend setters, and it would spark a lot of accessories that would convert the 48V to 12V or give a roadmap of how to do it.

The DC/DC converters obviously work, but they also have a high fail rate so they are generally shied away from for anything that is needed for safety. In this case they could make 48V the main bus which powers most everything and ECUs, and use a DC/DC for the 12V accessory bus so if your DC/DC crapped out you would only be out some accessories Either that or you just build the DC/DC into the board for the 12V accessory similar to how it works for supplying various voltages for USB plugs, etc.

This isn't my area (Electrical engineering) but I have been around the conversations for a while trying to determine cost/benefit for using higher voltage levels in commercial vehicles from a system perspective.

Interestingly the 48V was chosen over the initially proposed 42V to help the transition as it did not require a special battery. A lot of 48V systems and 24V systems (European commercial trucks) are just multiple 12V batteries in series to remove the requirement for unique batteries. Many 48V accessory systems work similar to the battery pack in the Hummer EV where they are connected in parallel when charging from the 12V system alternator and switched to series connection when there is a needed draw (which does not happen while charging in these cases obviously).

When it's engineered properly, a DC/DC converter is as reliable as any other electrical device. I'm sure that Tesla could easily design their own to work on the CT. Standard electrical engineering would call for the converter to be on its own circuit so that if something went wrong with it, it would just trigger a circuit breaker for that one circuit.

 

[Mrbrock]

I just posted the EPA docs in a separate thread but the actual pack voltage is 816 so that can help, with determining pack structure.

 

[JulienW]

I just posted the EPA docs in a separate thread but the actual pack voltage is 816 so that can help, with determining pack structure.

We kinda get hung on voltage but in reality there is no such thing as actual pack (or any) voltage. The voltage is always dynamically changing. For instance a Lit-ion cell can vary from 3V at low charge to 4.2V at a full charge. Also we know that the CT is a split pack so in the filing that would be 408V each. So 408V could be 100 (or couple more or less) in series which would be between about 300V to about 420V with 408V being nominal.

 

[terranx]

Looks like there's a lot of information in those EPA docs that aren't accurate. Lists all 3 motors as permanent magnet, claims a 1:1 gear ratio. And there is a comment in there saying it's dummy data for the sake of getting the CoC

But assuming the battery stuff is accurate, that voltage would put it at a 220s structure. If we assume ~93Wh per cell, that would probably make it 220s6p

We kinda get hung on voltage but in reality there is no such thing as actual pack (or any) voltage. The voltage is always dynamically changing. For instance a Lit-ion cell can vary from 3V at low charge to 4.2V at a full charge. Also we know that the CT is a split pack so in the filing that would be 408V each. So 408V could be 100 (or couple more or less) in series which would be between about 300V to about 420V with 408V being nominal.

Generally these docs quote nominal voltage (i.e 3.7-3.75v per cell)

 

[JulienW]

.....But assuming the battery stuff is accurate, that voltage would put it at a 220s structure. If we assume ~93Wh per cell, that would probably make it 220s6p....

It is a split pack so it can't be 220s.

 

[terranx]

It is a split pack so it can't be 220s.

They could probably split the 220 to 110 when needed for charging. But during operation it would effectively be 220.

 

[AlanSubie4Life]

Placeholder values, but some reasonably close as discussed in two other threads lol.

I’m not sure about 220 but certainly seems close, and could be correct. There are minor issues which may be non-issues:
'Predicting Battery Sizes'
Predicting Battery Sizes

 

[Tam]

Would someone explain how the Cybertruck battery arrangement works for 400V and 800V charging?

Jason Cammisa explained:

Four 200V units are arranged in parallel for 800V operation for all 3 motors. Is that a typo? 200V in parallel should yield 200V and 200V x 4 in series would yield 800V shouldn't it?

For 400V charging, there's a switch to take them all from series to parallel: I assume one 200V in series with another 200V to get 400V and do the same with the other 2 units, then combine those 400V in parallel for 400V charging when 800V V4 stations are not deployed?

Is the switch mechanical or electronic?

 

[AlanSubie4Life]

Would someone explain how the Cybertruck battery arrangement works for 400V and 800V charging?

Jason Cammisa explained:

Four 200V units are arranged in parallel for 800V operation for all 3 motors. Is that a typo? 200V in parallel should yield 200V and 200V x 4 in series would yield 800V shouldn't it?

For 400V charging, there's a switch to take them all from series to parallel: I assume one 200V in series with another 200V to get 400V and do the same with the other 2 units, then combine those 400V in parallel for 400V charging when 800V V4 stations are not deployed?

Is the switch mechanical or electronic?

It’s a typo. Four in series for 800 volts (aka 920V). Split in half 2 series, 2 parallel for 400V charging.

Max voltage of V3 Supercharger is allegedly 480V so 960V pack will work.

Switches look mechanical - like contactors I would think?

This four module thing is interesting. That might speak against the 220s pack. Because that would require a 55s pack if there really are four 200V elements. That 55s pack is too long for a single module I think (more than double the length of Model Y pack). So would have to be 5 modules of length 11 which seems odd.

Anyway we’ll see.


Predicting Battery Sizes

 

[JulienW]

Would someone explain how the Cybertruck battery arrangement works for 400V and 800V charging?

Jason Cammisa explained:

Four 200V units are arranged in parallel for 800V operation for all 3 motors. Is that a typo? 200V in parallel should yield 200V and 200V x 4 in series would yield 800V shouldn't it?

For 400V charging, there's a switch to take them all from series to parallel: I assume one 200V in series with another 200V to get 400V and do the same with the other 2 units, then combine those 400V in parallel for 400V charging when 800V V4 stations are not deployed?

Is the switch mechanical or electronic?

I remember hearing that instead of 2-400V packs it was 4-200V packs. If so they would be 4 packs in series and would be split into 2 packs in series and the 2s and 2s packs being parallel for V3 Supercharging.

EDIT: Alan beat me to the Post.

 

[gtg465x]

From the post by gtx I quoted in my reply to gtx.

“Y’all… 136 miles out of 340 is 40%. Adding 40% in 15 minutes is not indicative of a great charging curve or c-rate. Pretty much every other battery type Tesla offers adds 50% in 15 minutes. Heck, even my Model 3 RWD standard range adds 50% or 136 miles in 15 minutes, and it’s one of the slowest charging Tesla models.”

50% x 80kwh = 40kwh
40% x 130kwh = 52kwh

40kWh in 15 min is less than 52kwh in 15 minutes. That is what I was pointing out. Gtx suggests the CT c-rate based on %/min is worse than other Tesla batteries. I was pointing out % doesn’t work, you have to use actual energy which is how you get c-rate.

C-rate already takes into account the size of the battery. If you charge a 50 kWh battery at a 2C c-rate, that means you're charging at 100kW. To charge a 100 kWh battery at the same c-rate, it needs to charge at 200 kW.

15 minute average charging c-rates = (kWh added in 15 minutes * (60/15)) / battery capacity kWh

Model S / X (Panasonic 1865) = (47 kWh * (60/15)) / 100 kWh = 1.9C
Model 3 / Y LR / P (Panasonic 2170) = (38 kWh * (60/15)) / 82 kWh = 1.9C
Model 3 RWD (CATL LFP) = (29 kWh * (60/15)) / 60 kWh = 1.9C
CyberTruck (4680) = (49 kWh * (60/15)) / 130 kWh = 1.5C

 

[terranx]

Seems pretty similar to the model y AWD, which makes sense since that also had the 4680s

 

[AlanSubie4Life]

130 kWh

Still TBD, but seems like a lot of data pointing to 123kWh as reported, not 129kWh as the 42.9kWh/100mi with 340 miles would suggest. (We’ll see.)

Small adjustment in any case.

 

[gtg465x]

Still TBD, but seems like a lot of data pointing to 123kWh as reported, not 129kWh as the 42.9kWh/100mi with 340 miles would suggest. (We’ll see.)

Small adjustment in any case.

Same result in terms of c-rate since I used percentage of usable range to get kWh added in 15 minutes... (123 kWh * .955 * (136/340) * (60/15)) / 123 kWh = 1.5C still

I just hope the CT can charge faster on V4 like what's his face said. I will take back everything bad I ever said about 4680. Could be that they are capable of respectable c-rate, but just limited by V3 voltage due to the way they have the pack configured. Also makes me wonder whether Model Y 4680 is set up the same way and will also get a boost from V4 800v charging.