48V questions...

[JeffKeryk]

Calling @UncleDave @OVERKILL @JHZR2 and others...

We know the new Cybertruck is a 48V system. I have a few questions for the experts, which I am not...
I understand the basics; higher voltage offers the same power at lower current. This reduces heat and allows for use of smaller (lighter) wire and therefore less copper.
I am sure there is more...

What about lights, power seats, etc?
If this is "better", why hasn't it been done yet? Are there other vehicles? Do you expect a major switch to 48V or is it not worth it?
Other benefits? Drawbacks?

Thanks in advance; I appreciate your thoughts.

 

[dogememe]

Absolutely NOTHING HAS to be 12V on the vehicle, except maybe the trailer light connector... When you are Tesla and design pretty much everything in-house you can just redesign stuff to run off 48V or even just add a cheap DC to DC converter circuit on the item itself if you don't want to redesign the whole item.

Legacy automakers are going to have a harder time with this since they reuse components across different models and buy more off-the-shelf or slightly customized stuff from third-party suppliers. Of course, you can request whatever you want from your suppliers, and they will make it for you, but it will require collaboration, time, and money.

 

[joegreen]

I think some Audi or maybe Mercedes use 48v. May be wrong though

 

[JeffKeryk]

Absolutely NOTHING HAS to be 12V on the vehicle, except maybe the trailer light connector... When you are Tesla and design pretty much everything in-house you can just redesign stuff to run off 48V or even just add a cheap DC to DC converter circuit on the item itself if you don't want to redesign the whole item.

Legacy automakers are going to have a harder time with this since they reuse components across different models and buy more off-the-shelf or slightly customized stuff from third-party suppliers. Of course, you can request whatever you want from your suppliers, and they will make it for you, but it will require collaboration, time, and money.

The supply chain issue came to mind which is 1 reason I asked about the accessories. Manufacturing lives and dies by the supply chain.

 

[brianl703]

Absolutely NOTHING HAS to be 12V on the vehicle, except maybe the trailer light connector...

The cigarette lighter socket might need to be 12V, unless those have been declared obsolete. I don't think USB-C tire inflators are made yet...

 

[IndyIan]

I think Tesla decided to spend the money and time to figure it out on the Cybertruck, and their consumer base is willing to try something new, and they don't have a pile of dealers who will complain about new diag tools or whatever they need to work on 48v cars.
Seems like they are well positioned to make the switch over.

 

[Shel_B]

Tesla Sends Free Guide to 48-Volt Architecture To Its Competitors

Click Here for One Article on the Subject. There are others, including references in some videos that have been posted in other recent threads about the Cybertruck.

 

[Vercingetorix]

Absolutely NOTHING HAS to be 12V on the vehicle, except maybe the trailer light connector... When you are Tesla and design pretty much everything in-house you can just redesign stuff to run off 48V or even just add a cheap DC to DC converter circuit on the item itself if you don't want to redesign the whole item.

Legacy automakers are going to have a harder time with this since they reuse components across different models and buy more off-the-shelf or slightly customized stuff from third-party suppliers. Of course, you can request whatever you want from your suppliers, and they will make it for you, but it will require collaboration, time, and money.

“Legacy” automakers already have 48v since 2019.

 

[proveitwithdata]

“Legacy” automakers already have 48v since 2019.

i think vw started with 48v systems, bentayga comes to mind. Its also about packaging. With 48v system, i now can design or purchase smaller sized accessories like ac compressor, eps systems.

 

[Vercingetorix]

i think vw started with 48v systems, bentayga comes to mind. Its also about packaging. With 48v system, i now can design or purchase smaller sized accessories like ac compressor, eps systems.

I think the big reason was the 48v starter/alternator. 12v initial start from cold, 48v for start stop and alternator.

 

[SC Maintenance]

12VDC is a legacy to automotive from the 60's. Back then it was 12V because the battery was the most expensive part of the system so making one with fewer cells was cheaper. It was 6V before that. Commercial vehicles have been 24V for as long as Auto's have been 12VDC for the same reason auto's are now going 48VDC. I think a lot of military stuff is even higher - I forget which though - 60VDC maybe?

The commercial vehicle world is still talking about going 48VDC - or even higher, but I think the hesitation exists from an industry standpoint as they cross pollinate a lot with industrial use, and 24VDC is still the industrial standard for controls - PLC, instrumentation, sensors, etc. The industrial world is much larger for stuff like that, and they won't go to 48VDC because at 42 VDC you need UL - because that high of voltage is more likely to harm a human that is shocked by it. So Industrial won't move up, and hence commercial vehicles hesitate because then they need special stuff which would be less available.

 

[JHZR2]

I don’t know the extent that things are 48v. Could just be from point a to b, with some larger consumers like power steering… not sure if small consumers are 12 vs 48v.

Heavy trucks are starting to have major aux systems at 800v.

No real reason/benefit to a load that is fed with smaller than 16ga automotive wire getting 48v, imo.

 

[Gyro Gearloose]

48 V would be a benefit for heavy current drawing systems like power steering and electric climate control. Wiring and motors can be smaller and lighter for equivalent power delivery. I think one of the reasons voltage stopped at 12 V in the past was that bulb filaments get thinner and more fragile the higher the voltage of the lamp. Now that everything is LED with power regulators controlling the voltage all kinds of possibilities open up. I come from an industrial background where guys worked on live 24 V systems with no concerns. I'm not sure you could be so dismissive of 48V.

 

[Number_35]

I understand the basics; higher voltage offers the same power at lower current. This reduces heat and allows for use of smaller (lighter) wire and therefore less copper.
I am sure there is more...

Yup, you've got the basics. Power (Watts) = voltage (Volts) x current (Amperes).

Let's say an accessory, a rear-window defroster, for example, requires 120 W.

Running on (nominally) 12 V, it will draw 10 A.

If run on 48 V, it would only draw 2.5 A.

The lower current would allow for the use of a smaller gauge of wire.

 

[SHOZ]

Industrial is usually 24v. They talked about going to 24v for car a few years ago. Wish they would have as the world of 24v dc controls is huge.

 

[Torrid]

This is another one of those things that benefits from lack of voltage drop due to required draw. I don't know if many on here used to install aftermarket sound systems, but if you didn't have the proper supporting high farad capacitors or a really strong upgraded alternator you'd watch your headlights dim every time the bass hit. That whole guide that Tesla put together on how to make a 48V vehicle and sent to other companies is a pretty big middle finger, but at the same time it's a huge shout out to common sense. The average new car has a huge electricity demand and going to 48V would solve a lot of issues, including cold starts on ICE vehicles. Literally if no other changes happened other than switching to 48V it would require 1/4 of the amperage to start a vehicle. That's a huge difference, especially in sub zero temperatures.

Industrial is usually 24v. They talked about going to 24v for car a few years ago. Wish they would have as the world of 24v dc controls is huge.

At this point it's probably best to skip 24V just because of power demand, but I'd welcome 24V too. It's crazy what we ask of 12V and it has so many drawbacks with current tech. I spend 11 years in the 12V industry and at that time it was already taxed. It's amazing how long that architecture has existed.

 

[brianl703]

Commercial vehicles have been 24V

Only in Europe. In the USA even 18-wheelers run on a 12V system. Military vehicles tend to be 24V systems.

 

[JeffKeryk]

I don’t know the extent that things are 48v. Could just be from point a to b, with some larger consumers like power steering… not sure if small consumers are 12 vs 48v.

Heavy trucks are starting to have major aux systems at 800v.

No real reason/benefit to a load that is fed with smaller than 16ga automotive wire getting 48v, imo.

Does the drive by wire steering come into play?

 

[Torrid]

Does the drive by wire steering come into play?

I'd say so. With no connection to the wheels the electric motors are doing everything. It's not like both of my current cars which are electric assist for power steering. It takes a lot less effort to use higher voltage to control the steering motors.

 

[SC Maintenance]

Only in Europe. In the USA even 18-wheelers run on a 12V system. Military vehicles tend to be 24V systems.

Commercial vehicles like, mobile cranes, combines, harvesters, excavators and other stuff has run on 24V for a long time. Possibly commercial isn't the correct word. Maybe off highway or something else is the correct word.