Tesla HGV completes a 500 mile drive fully laden

[Fintray]

They talk about "immersion cooling" of the live electrical conductors.
Have they really got the live cables literally swimming in the coolant flow? And then insulated the whole fluid and cable combination on the outside after that? Is that safe? Surely the risk of leaks and therefore shorting, must be really high in a flexible cable, and with the seals? What dark arts are going on here?

They could use an insulating oil as the coolant medium though.

[Oldgreybeard]

Immersion cooling has been in used for decades in HV transmission systems. Every 11kV to 230 V (strictly speaking 400V three phase) transformer, including all those on poles, use immersion cooling. Same goes for the bigger stuff, taking the 33kV, 66kV and 132kV grid voltage down to the 11kV used to supply local networks.

[Mart]

just put a regen brake and a battery on the trailer then. Could even let it double as a pusher motor for initial starts or manoeuvering round yards...

Yep, sounds great. I wonder how much a small motor* would cost, although now I think about it, the battery may be a problem, as regen can involve a lot of power, so a small battery may not be able to handle the power (as oppossed to the energy).

*Small as in power, not size, since Elon said the motors on the Semi are each about the size of a football. Hard to comprehend that v's a huge V6/V8 diesel truck engine.

If you considered the trailer equipment as part of the combo's capability it needn't be seen as a handicap, as it could be balanced by slightly less capacity/provision on the tractor. There usually seems to be a huge empty space under an artic trailer which has to be fenced off to stop people driving under it, just have a battery cupboard instead.
I gather that full power is not used most of the time, so a saving on the tractor could be a selling point...

Yeah, fun mental exercise. I think that's how electric passenger trains work, where each passenger carriage has motors, so they add weight and power.

So, as you say, and also answers Dan's point, you could have a bit less weight on the tractor to balance the 'smart trailer'.

I wonder if the momentum 'wasted' by trailer friction brakes is significant, and worth the effort, or not? Maybe we are chasing the perfect at the cost of the good?

Would be fascinating to know how the brakes / regen work on these BEV trucks*. I'm totally guessing that light braking would be handled by the tractor regen. It sounds good in theory, but even at very light levels of deceleration, I assume an unbraked trailer pushing the tractor is a serious concern, so maybe trailer brakes are used a lot, which would be a waste worth considering ...... I assume(?)

*Specifically artics, as it's probably easier for BEV rigids.

[openspaceman]

Immersion cooling has been in used for decades in HV transmission systems. Every 11kV to 230 V (strictly speaking 400V three phase) transformer, including all those on poles, use immersion cooling. Same goes for the bigger stuff, taking the 33kV, 66kV and 132kV grid voltage down to the 11kV used to supply local networks.

The nominal 600V DC supply from the substation to the conductor rails seemed to be an oil cooled loop on the old british railways 3rd rail system.

[Oldgreybeard]

Immersion cooling has been in used for decades in HV transmission systems. Every 11kV to 230 V (strictly speaking 400V three phase) transformer, including all those on poles, use immersion cooling. Same goes for the bigger stuff, taking the 33kV, 66kV and 132kV grid voltage down to the 11kV used to supply local networks.

The nominal 600V DC supply from the substation to the conductor rails seemed to be an oil cooled loop on the old british railways 3rd rail system.

Makes sense, given the current involved. I had the chance to look inside an old 11kV to 400V distribution transformer a few years ago. Massive amount of H&S paraphernalia, as apparently the oil used is pretty toxic stuff (contains dioxins, IIRC). Impressive to see how clean everything looked when the lid was lifted, though, despite being around 40 years old the inside looked as if it had been made the day before.

[openspaceman]

Have a search on polychlorinated biphenol oils there was an outcry about it leaking from substation transformers many yeas back.

[chris_n]

Immersion cooling has been in used for decades in HV transmission systems. Every 11kV to 230 V (strictly speaking 400V three phase) transformer, including all those on poles, use immersion cooling. Same goes for the bigger stuff, taking the 33kV, 66kV and 132kV grid voltage down to the 11kV used to supply local networks.

The nominal 600V DC supply from the substation to the conductor rails seemed to be an oil cooled loop on the old british railways 3rd rail system.

Our underground 500v DC overhead line railway system electrical equipment was oil cooled. As were all of the underground transformers, the Sparkys used to have to take oil samples occasionally.

[Tinbum]

Data plate on our transformer before it went on the pole, showing oil.


l

[Mart]

For anyone desperate for some numbers, before more official data arrives, then the man maths carried out by some Youtubers based on the info given by Tesla, especially a recent tweet by Elon that the 500 mile trip achieved 1.7kWh/mile, we get:

Guestimate of battery capacity ~900kWh
Guestimate of the output of the Megachargers ~1.3MW*

*Edit - Actually that's the average charge rate needed to meet the claimed 70% in 30mins. Assuming the rate falls, as the battery charge increases, then the peak power would need to be higher.



I'm not being bitchy (honest), but there was another BEV semi launch this last week, by Daimler for the Freightliner eCascadia full size semi, class 8 truck.

The eCascadia comes in a few varieties, upto 470bhp, battery upto 438kWh, can do up to 230 miles of range, and charge at up to 270kW.

Given that Daimler is the largest single seller of trucks in Europe and the US, I really think they'll now need to lift their game. Back in 2017 after the semi launch, Daimler weren't impressed with Tesla's claimed 500 mile range, stating:

If Tesla really delivers on this promise, we’ll obviously buy two trucks — one to take apart and one to test because if that happens, something has passed us by. But for now, the same laws of physics apply in Germany and in California.

Penske takes delivery of electric Freightliner eCascadia semi trucks

[dan_b]

Thanks for the info on immersion cooling for HV transformer stuff etc.
My surprise now is that those are stationary installations, and are using oil-based coolant.

This seems to be a water (glycol?) based coolant, and is in a flexible cable that humans will abuse. They must be very confident of the quality of the cables/insulators/seals?