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Audi also has a 48v architecture in use for mild hybrids like my SQ5. This is an older article but explains it well https://www.greencarcongress.com/2017/06/201

Audi also has a 48v architecture in use for mild hybrids like my SQ5. This is an older article but explains it well https://www.greencarcongress.com/2017/06/20170602-audi.html https://www.greencarcongress.com/2017/06/20170602-audi.html My 2021 is fully 48v except for an inverter for necessary 12v circuits (like cigarette outlets and the jumper pins) and a small motorcycle battery that is used for minimal 12v functionality. The mild hybrid battery is under the rear seats and spins the alternator to keep accessories running. https://www.autoweek.com/news/a36331077/48-volt-hybrid-system-explained/ https://www.autoweek.com/news/a36331077/48-volt-hybrid-syste... My guess is that handing this out is a very nice thing to do but perhaps irrelevant in a world where 400v and 800v drive systems are the state of the art. Those systems can’t rely on the car body as a common ground for all sources of current and have a lot of inherent safety concerns that force a lot of electrical engineering that my old Camaro didn’t need to have.

arcticbull 3y ago
Most automotive parts are 12V so that just means due to economy of scale, 48V parts are more expensive. They are trying to reduce their cost basis by getting everyone to move over to a common, more efficient voltage spec. This is good industry advocacy.
- CodeWriter23 3y ago
  There's a crossover where ROI results in lower wiring costs.
gleenn 3y ago
My understanding was that nearly every production vehicle on the road is 12V and that Tesla and perhaps Audi as you mentioned are doing things differently. Who is using 400-800V systems? That sounds extremely dangerous.
- deleted 3y ago
  [deleted]
- Turskarama 3y ago
  They're getting mixed up, the 400-800V systems are _only_ for the motors, everything else in the car still uses low voltage. In fact, afaik every single electric car has two separate systems. There's a high voltage system (the main battery and motor(s)) and the low voltage (almost always 12v) system, usually with a traditional lead-acid 12v battery that is charged via a DC-DC converter connected to the high voltage battery.
  - Kirby64 3y ago
    Not true in most EVs regarding 'only the motors'. The AC/heat pump compressor is run off the HVDC, typically. Since it runs for long periods of time and consumes kilowatts, you want to run it straight off the main HV battery. Also, any vehicle that still uses resistive heating (older EVs tended to do this, Tesla included) use the HVDC for that.
  - Moto7451 3y ago
    I’m speaking about the power planes. What they drive is irrelevant from the standpoint that higher voltage systems create safety issues that lower voltage systems do not have. No one is going to be ok with “occasionally being shocked by 48v” or “occasionally seeing arcing in their car from a high voltage system.” Running 48v to a radio is not an engineering marvel. Running it safely and reliably in an automotive environment full of vibration and weather is. If you can do that with 400v, I argue you can do it with 48v, so the secret sauce they’re sharing is less relevant than if they did this ten years ago.
    - Turskarama 3y ago
      I feel like you're mixing up points now, running 48V is fine _because_ the voltage is low enough that it's unlikely to kill anyone if you mess it up. The 400V system in the meantime has a lot more care taken and limiting the systems it works on to ONLY high power systems lessens the number of things that can go wrong.
- nine_k 3y ago
  A ton of trucks are 24V, especially in EU. 48V in automotive industry is something new; I can't remember seeing it on any commercial trucks. Electric bikes use 12V, 24V, 28V and even 56V. Nobody loves the weight and the cost of thick copper wires. 400V or 800V are charging voltages, because it's the operation with the highest current; to keep it manageable while transferring more energy you need really high voltages. AFAICT, motors inside a Tesla use 320V. I suppose that ICE-electric hybrids also use some reasonably high voltage to feed the electric motors.
- dreamcompiler 3y ago
  Tesla uses 800v only to run the Cybertruck's drive motors. Every other electric load in the truck uses 48v. Both of these are much higher in the Cybertruck than all other Tesla models. All other Tesla models use 400v [IIRC] for the drive motors and 12v for everything else.
  - 1970-01-01 3y ago
    Newer builds are using 16v lithium batteries for low voltage.
  - Kirby64 3y ago
    Pretty sure the AC/heat pump on the Cybertruck runs off the 800V pack. Since it consumes so much power for long periods of time, it makes little sense to run it off the 48V. Existing other Tesla's use the main pack voltage for AC/heat pump.
    - dreamcompiler 3y ago
      Good point and makes sense.
- inferiorhuman 3y ago
  Mercedes introduced their 48V hybrid in 2016. Kia in 2018. Peugeot just introduced theirs this year. Jalopnik was talking about the "48V revolution" in 2017: https://jalopnik.com/everything-you-need-to-know-about-the-upcoming-48-volt-1790364465 https://jalopnik.com/everything-you-need-to-know-about-the-u...
  - hef19898 3y ago
    At least once delivered early then? Sharing tech 6 years before their annoncement of sharing it! Alternative take: Everybody else was aware 48 V networks work as well for decades, there was just no real benefot in switching yet. And Tesla has nothing to do with it. What's next, Tesla annoncing they will share the revolutionary tech of windscreens and doors?
- SV_BubbleTime 3y ago
  >Who is using 400-800V systems? That sounds extremely dangerous. Every electric vehicle. And yes, it is dangerous to work on the HV circuit.
  - Moto7451 3y ago
    Not all of them. The Kia Niro I’m driving as a rental this week has a 240v battery. Level 3 charging it feels wildly slow compared to my car. But yes, you’re right the increased voltages add a lot of risk that has to be managed.
    - crishoj 3y ago
      And, thankfully, high-voltage systems are extremely well-managed in EVs. Evidence in support of this claim is that EVs are statistically 4-5 times less likely to catch on fire compared to ICE vehicles. https://gmauthority.com/blog/2023/11/ev-fires-less-likely-than-ice-vehicle-fires-research-finds/ https://gmauthority.com/blog/2023/11/ev-fires-less-likely-th...
ReactiveJelly 3y ago
Not sure how relevant this is, but curious readers might be interested: In those 400-800 volt systems, the low-voltage system is used to wake up the battery's computer and close a normally-open contactor inside the battery that connects the high-voltage system. So indeed they might not ground HV stuff to the chassis, and the hundreds-of-volts sources are disconnected if the car is turned off and unplugged.
- crishoj 3y ago
  Exactly. Apart from waking up the vehicle and closing the high voltage connectors, a whole myriad of things run off the low-voltage system, including lights, climate, infotainment and most (if not all) actuators.
grecy 3y ago
> This is an older article but explains it well https://www.greencarcongress.com/2017/06/20170602-audi.html https://www.greencarcongress.com/2017/06/20170602-audi.html From the article: > The 12-volt system is connected to the main electrical system via a DC/DC converter > Audi also offers the new MHEV technology with the conventional 12-volt electrical system > 48-volt vehicle electrical system. In a different layout—without MHEV—the 48-volt constant voltage system already entered volume production in 2016 as the Audi SQ7 TDI. In this vehicle, the alternator still operates on a 12-volt basis, and a DC converter couples the 48-volt electrical subsystem > Small consumers such as control units or lights will remain in the 12-volt system well into the future, however The article makes it very clear that what Audi are doing is not similar to what Tesla have done with the Cybertruck. The Cybertruck has no 12v system, everything runs on 48v. The power seats. The seat heaters. The rear defroster, the interior lights, literally everything. They can have much smaller and lighter wires and use way less copper. Using a 48V system for a mild hybrid is very common, even Jeep do that.
- maxerickson 3y ago
  Realistically, using 12 volt and 48 volt for accessory systems are pretty similar. 48 volts just reduces your current, and you have to design everything for ~56 volts instead of ~14. But it's not really a different exercise.
  - grecy 3y ago
    > 48 volts just reduces your current "Just" is doing an awful lot of work in that sentence. Yes, moving from 12v to 48v reduces the current. That means you can have much smaller gauge wires, it means you lose a lot less power ( powerloss = (II)R ), it means you use a lot less copper and it means you save a lot of weight on wiring and connectors. That is literally the point.
    - deleted 3y ago
      [deleted]
    - maxerickson 3y ago
dreamcompiler 3y ago
> except for an inverter for necessary 12v circuits Nitpick: That's a DC-DC converter, not an inverter.
bhauer 3y ago
> My guess is that handing this out is a very nice thing to do but perhaps irrelevant in a world where 400v and 800v drive systems are the state of the art. The high-voltage system for the drive motors, whether 400V or 800V, is unrelated to the low-voltage system for accessories. The transition from 12V to 48V is concerning the low-voltage system. Prior to the Cybertruck, no automobile ever had a fully 48V low-voltage system. To learn more about how this is a big deal, check out Jason Cammisa's video on the subject. I've cued it to the specific topic in the [1] link below. [1] https://youtu.be/L6WDq0V5oBg?si=dbzsPMAkvmGiQQ8n&t=613 https://youtu.be/L6WDq0V5oBg?si=dbzsPMAkvmGiQQ8n&t=613
sbierwagen 3y ago
>and the jumper pins It can be started through the converter? That takes something like a hundred amps. It must be pretty beefy.
- phire 3y ago
  No. For safety, hybrids and electric vehicles physically disconnect the high-voltage battery from everything when it's off with massive relays. So you can end up in the somewhat stupid situation where your high-voltage battery is fully charged, but you can't do anything because the tiny 12v motorcycle battery is flat. Starting simply requires enough 12v current to close a relay, the amps going though the "jumper pins" are tiny. And once the relay is closed, the high-voltage battery can keep the relay closed and charge the 12v battery via the dc-dc converter. The amount of current to "jump" a hybrid or electric car is so small that they really should just install a USB-C cable, so you could just use your phone to jump start it.
  - deleted 3y ago
    [deleted]
  - sbierwagen 3y ago
    That describes the situation where the 12V battery is flat but the HV battery is charged. But what happens if the HV battery is flat on a non-plug in hybrid? Can it be charged from 12V?
    - ace2358 3y ago
      Wouldn’t you just start the car if the HV was flat and the LV was charged? If they’re both flat I agree, I’m curious what you do.
      - phire 3y ago
        There is no 12v starter motor, it always just uses one of the large motor-generator units to start the engine, and in the Prius drive chain, they require 600v (boosted from 200v from the HV battery). So if the HV battery is flat, you can't start the engine to charge it.
codeulike 3y ago
Its not that same, that Audi still had a 12V system because all the commodity parts (control units, interior lights) are built to run on 12V. What Tesla are doing is getting rid of 12V entirely so that every little window raising motor or interior light or actuator to move the seats is running on a 48V system.

arcticbull 3y ago

Most automotive parts are 12V so that just means due to economy of scale, 48V parts are more expensive. They are trying to reduce their cost basis by getting everyone to move over to a common, more efficient voltage spec. This is good industry advocacy.

CodeWriter23 3y ago
There's a crossover where ROI results in lower wiring costs.

gleenn 3y ago

My understanding was that nearly every production vehicle on the road is 12V and that Tesla and perhaps Audi as you mentioned are doing things differently. Who is using 400-800V systems? That sounds extremely dangerous.

deleted 3y ago
[deleted]
Turskarama 3y ago
They're getting mixed up, the 400-800V systems are _only_ for the motors, everything else in the car still uses low voltage. In fact, afaik every single electric car has two separate systems. There's a high voltage system (the main battery and motor(s)) and the low voltage (almost always 12v) system, usually with a traditional lead-acid 12v battery that is charged via a DC-DC converter connected to the high voltage battery.
- Kirby64 3y ago
  Not true in most EVs regarding 'only the motors'. The AC/heat pump compressor is run off the HVDC, typically. Since it runs for long periods of time and consumes kilowatts, you want to run it straight off the main HV battery. Also, any vehicle that still uses resistive heating (older EVs tended to do this, Tesla included) use the HVDC for that.
- Moto7451 3y ago
  I’m speaking about the power planes. What they drive is irrelevant from the standpoint that higher voltage systems create safety issues that lower voltage systems do not have. No one is going to be ok with “occasionally being shocked by 48v” or “occasionally seeing arcing in their car from a high voltage system.” Running 48v to a radio is not an engineering marvel. Running it safely and reliably in an automotive environment full of vibration and weather is. If you can do that with 400v, I argue you can do it with 48v, so the secret sauce they’re sharing is less relevant than if they did this ten years ago.
  - Turskarama 3y ago
    I feel like you're mixing up points now, running 48V is fine _because_ the voltage is low enough that it's unlikely to kill anyone if you mess it up. The 400V system in the meantime has a lot more care taken and limiting the systems it works on to ONLY high power systems lessens the number of things that can go wrong.
nine_k 3y ago
A ton of trucks are 24V, especially in EU. 48V in automotive industry is something new; I can't remember seeing it on any commercial trucks. Electric bikes use 12V, 24V, 28V and even 56V. Nobody loves the weight and the cost of thick copper wires. 400V or 800V are charging voltages, because it's the operation with the highest current; to keep it manageable while transferring more energy you need really high voltages. AFAICT, motors inside a Tesla use 320V. I suppose that ICE-electric hybrids also use some reasonably high voltage to feed the electric motors.
dreamcompiler 3y ago
Tesla uses 800v only to run the Cybertruck's drive motors. Every other electric load in the truck uses 48v. Both of these are much higher in the Cybertruck than all other Tesla models. All other Tesla models use 400v [IIRC] for the drive motors and 12v for everything else.
- 1970-01-01 3y ago
  Newer builds are using 16v lithium batteries for low voltage.
- Kirby64 3y ago
  Pretty sure the AC/heat pump on the Cybertruck runs off the 800V pack. Since it consumes so much power for long periods of time, it makes little sense to run it off the 48V. Existing other Tesla's use the main pack voltage for AC/heat pump.
  - dreamcompiler 3y ago
    Good point and makes sense.
inferiorhuman 3y ago
Mercedes introduced their 48V hybrid in 2016. Kia in 2018. Peugeot just introduced theirs this year. Jalopnik was talking about the "48V revolution" in 2017: https://jalopnik.com/everything-you-need-to-know-about-the-upcoming-48-volt-1790364465 https://jalopnik.com/everything-you-need-to-know-about-the-u...
- hef19898 3y ago
  At least once delivered early then? Sharing tech 6 years before their annoncement of sharing it! Alternative take: Everybody else was aware 48 V networks work as well for decades, there was just no real benefot in switching yet. And Tesla has nothing to do with it. What's next, Tesla annoncing they will share the revolutionary tech of windscreens and doors?
SV_BubbleTime 3y ago
>Who is using 400-800V systems? That sounds extremely dangerous. Every electric vehicle. And yes, it is dangerous to work on the HV circuit.
- Moto7451 3y ago
  Not all of them. The Kia Niro I’m driving as a rental this week has a 240v battery. Level 3 charging it feels wildly slow compared to my car. But yes, you’re right the increased voltages add a lot of risk that has to be managed.
  - crishoj 3y ago
    And, thankfully, high-voltage systems are extremely well-managed in EVs. Evidence in support of this claim is that EVs are statistically 4-5 times less likely to catch on fire compared to ICE vehicles. https://gmauthority.com/blog/2023/11/ev-fires-less-likely-than-ice-vehicle-fires-research-finds/ https://gmauthority.com/blog/2023/11/ev-fires-less-likely-th...

ReactiveJelly 3y ago

Not sure how relevant this is, but curious readers might be interested: In those 400-800 volt systems, the low-voltage system is used to wake up the battery's computer and close a normally-open contactor inside the battery that connects the high-voltage system. So indeed they might not ground HV stuff to the chassis, and the hundreds-of-volts sources are disconnected if the car is turned off and unplugged.

crishoj 3y ago
Exactly. Apart from waking up the vehicle and closing the high voltage connectors, a whole myriad of things run off the low-voltage system, including lights, climate, infotainment and most (if not all) actuators.

grecy 3y ago

> This is an older article but explains it well https://www.greencarcongress.com/2017/06/20170602-audi.html https://www.greencarcongress.com/2017/06/20170602-audi.html From the article: > The 12-volt system is connected to the main electrical system via a DC/DC converter > Audi also offers the new MHEV technology with the conventional 12-volt electrical system > 48-volt vehicle electrical system. In a different layout—without MHEV—the 48-volt constant voltage system already entered volume production in 2016 as the Audi SQ7 TDI. In this vehicle, the alternator still operates on a 12-volt basis, and a DC converter couples the 48-volt electrical subsystem > Small consumers such as control units or lights will remain in the 12-volt system well into the future, however The article makes it very clear that what Audi are doing is not similar to what Tesla have done with the Cybertruck. The Cybertruck has no 12v system, everything runs on 48v. The power seats. The seat heaters. The rear defroster, the interior lights, literally everything. They can have much smaller and lighter wires and use way less copper. Using a 48V system for a mild hybrid is very common, even Jeep do that.

maxerickson 3y ago
Realistically, using 12 volt and 48 volt for accessory systems are pretty similar. 48 volts just reduces your current, and you have to design everything for ~56 volts instead of ~14. But it's not really a different exercise.
- grecy 3y ago
  > 48 volts just reduces your current "Just" is doing an awful lot of work in that sentence. Yes, moving from 12v to 48v reduces the current. That means you can have much smaller gauge wires, it means you lose a lot less power ( powerloss = (II)R ), it means you use a lot less copper and it means you save a lot of weight on wiring and connectors. That is literally the point.
  - deleted 3y ago
    [deleted]
  - maxerickson 3y ago

dreamcompiler 3y ago

> except for an inverter for necessary 12v circuits Nitpick: That's a DC-DC converter, not an inverter.

bhauer 3y ago

> My guess is that handing this out is a very nice thing to do but perhaps irrelevant in a world where 400v and 800v drive systems are the state of the art. The high-voltage system for the drive motors, whether 400V or 800V, is unrelated to the low-voltage system for accessories. The transition from 12V to 48V is concerning the low-voltage system. Prior to the Cybertruck, no automobile ever had a fully 48V low-voltage system. To learn more about how this is a big deal, check out Jason Cammisa's video on the subject. I've cued it to the specific topic in the [1] link below. [1] https://youtu.be/L6WDq0V5oBg?si=dbzsPMAkvmGiQQ8n&t=613 https://youtu.be/L6WDq0V5oBg?si=dbzsPMAkvmGiQQ8n&t=613

sbierwagen 3y ago

>and the jumper pins It can be started through the converter? That takes something like a hundred amps. It must be pretty beefy.

phire 3y ago
No. For safety, hybrids and electric vehicles physically disconnect the high-voltage battery from everything when it's off with massive relays. So you can end up in the somewhat stupid situation where your high-voltage battery is fully charged, but you can't do anything because the tiny 12v motorcycle battery is flat. Starting simply requires enough 12v current to close a relay, the amps going though the "jumper pins" are tiny. And once the relay is closed, the high-voltage battery can keep the relay closed and charge the 12v battery via the dc-dc converter. The amount of current to "jump" a hybrid or electric car is so small that they really should just install a USB-C cable, so you could just use your phone to jump start it.
- deleted 3y ago
  [deleted]
- sbierwagen 3y ago
  That describes the situation where the 12V battery is flat but the HV battery is charged. But what happens if the HV battery is flat on a non-plug in hybrid? Can it be charged from 12V?
  - ace2358 3y ago
    Wouldn’t you just start the car if the HV was flat and the LV was charged? If they’re both flat I agree, I’m curious what you do.
    - phire 3y ago
      There is no 12v starter motor, it always just uses one of the large motor-generator units to start the engine, and in the Prius drive chain, they require 600v (boosted from 200v from the HV battery). So if the HV battery is flat, you can't start the engine to charge it.

codeulike 3y ago

Its not that same, that Audi still had a 12V system because all the commodity parts (control units, interior lights) are built to run on 12V. What Tesla are doing is getting rid of 12V entirely so that every little window raising motor or interior light or actuator to move the seats is running on a 48V system.