Cybertruck to use 48V instead of 12V?

[alan auerbach]

Since CT is such a new platform compared to any other Tesla it would make a lot of sense (economic sense due to the anticipated volumes, engineering due to benefits of the higher voltage) to use the 48V accessories power system instead of the conventional 12V. Do you think Tesla will make this leap? Cybertruck seems to be the perfect opportunity for this...

Edit: Just a TLDR recap for those that don't want to scroll through the comments: Consensus is Tesla will stick to 12V for the Cybertruck

Come on now -- I've barely recovered from the switch from the 6V of my early years to 12V, so I could never survive another one. Wasn't so long ago I finally tossed my collection of 6V bulbs, heater-motor, radio, ....

More seriously, 60 years ago I had a 36V tractor ("Electrac" by GE). Propelled by six 6V deep-discharge batteries. The attachments (mower, snowblower, welder, chainsaw, drill) were 36V DC. Served me well for a decade. Service needs were minimal, but when they arose, I was on my own.

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[Hoppi]

Cars already incorporate Ethernet for diagnostics, downloading etc but up until recently ethernet did not meet the industry's EMI requirements. Progress has been made in this area and I have to think that the multiple cameras in a modern Tesla must be using it.

I remember reading a number of years back that space x was using Ethernet for rocket internal communications because it was cheap and the risks of reliability could be mitigated by redundant systems. So clearly EM has a history of saving $$ by using Ethernet. If Tesla is not using Ethernet in its cars I’d be quite surprised.

 

[EVCanuck]

Should this thread be resurrected?

 

[Diehard]

Should this thread be resurrected?

The only new information is Elon’s comment indicating interest to Sandy. I say let’s just wait until CT update come out and see. Then we can talk about what we can do with that 48 when we know we have it. Speculation can be a good mental exercise but a waste of time if we end up getting 12V.

 

[Jhodgesatmb]

The low voltage system powers only low power stuff - no starting motor in particular. The modern lights are all LEDs so their current demands are small. The biggest low voltage loads are probably the computers, a blower here and there, motors that run the windows up and down and coolant circulation pumps. The rest is control valves etc. Thus I don't really see a lot of advantages to going to a 28 V system. What did you have in mind?

In the interview between Sandy Munro and Elon Musk Elon said that moving to 48v would be a good thing but didn't specify when they would do it.

 

[SentinelOne]

well, if it stays 12v, at least we should get a Li-on 12v Battery since that was announced for the refreshed s/x...add a bit or reliability vs historical 12v battery issues

 

[LoPro]

48V Power-over-ethernet I think was vaguely mentioned in the new interview. I guess less (theoretical) powerloss, less copper for same watts and power integrated in existing cheap standard of communications wires. I’m by no means an expert though. All may have been discussed before in the thread.

 

[Jhodgesatmb]

48V Power-over-ethernet I think was vaguely mentioned in the new interview. I guess less (theoretical) powerloss, less copper for same watts and power integrated in existing cheap standard of communications wires. I’m by no means an expert though. All may have been discussed before in the thread.

You can go review the interview but I think Elon was just giving an example that ethernet requires like 50V and that that is pretty minimal....not that it was their intention too use ethernet as their transport. He was talking about having smaller-gage wire and ethernet would be larger. That said, maybe POE isn't such a bad idea (not that I know).

 

[azjohn]

Getting rid of 12v lead acid batteries would be great

I used to race RC 1/8th scale RC Truggies that I converted from Nitro methane fuel and 1 thing I would do is use a step down going from 37 volts to 8 volts for the steering servo instead of using a separate NiCad 7 Volt battery pack which would save some weight and not have to worry about the small battery pack going dead. I would think Tesla could do something similar for their low voltage system

 

[Crissa]

Getting rid of 12v lead acid batteries would be great
...I would think Tesla could do something similar for their low voltage system

DC step-down is less efficient than the loss in most cases; your step-down has to be built to your consumption lest you waste lots of power.

The new OBD port requirement for motorcycles has left the new S and X platform Zeros losing up to a percent of charge a day (about the wattage of ten AA batteries) because they're using the big DC-DC board while the newer F platform uses an accessory battery and that covers the loss without the waste. So aux batteries have their place because they can be used for very variable power consumption down to tiny amounts.

Still no excuse for lead-acid, tho.

-Crissa

 

[OneLapper]

Let's all hope for 48vdc CT low voltage system.

Motorcoaches use 12vdc, 24vdc, and CANBUS systems. Imagine being able to combine all of that over one wire (power and communication)! The cost savings would be substantial. Literally, POE (Power Over Ethernet) vehicle. I have spent 100s of hours tracing wiring problems on coaches. A 48vdc POE structure would make finding problems much easier (with appropriate diagnostic tools).

Tesla talked about this and there was speculation that the MY would have this 48vdc POE type wiring system. As Sandy found out, that never happened.

Since the CT is such a bold statement in function over design, I wonder if Tesla is going make the leap to this technology.

I really don't see any downsides.

 

[azjohn]

DC step-down is less efficient than the loss in most cases; your step-down has to be built to your consumption lest you waste lots of power.

The new OBD port requirement for motorcycles has left the new S and X platform Zeros losing up to a percent of charge a day (about the wattage of ten AA batteries) because they're using the big DC-DC board while the newer F platform uses an accessory battery and that covers the loss without the waste. So aux batteries have their place because they can be used for very variable power consumption down to tiny amounts.

Still no excuse for lead-acid, tho.

-Crissa

I saw a recent Tweet from one of the big online EV sites that Tesla has now replaced the lead acid 12v batteries with Li on, I guess that is a step in the right direction. In the article there were + and -

 

[Billyboy]

Part of reason for 48V smaller wires is so robots could install the wires instead of current humans