Supercharger - Mountain View, CA (12 V2 stalls)

[evmile]

I expect the higher power will be needed when the 100 kWh packs are announced since they should be able to handle higher peak currents.

 

[wk057]

Thinner cable actually amounts to more resistive losses. Just because they're able to make the cable thinner through liquid cooling doesn't mean that it is more efficient. Personally, I prefer the existing cables. Less to go wrong, for sure. Liquid cooled cable is neat and all, but what happens when the pump in a pedestal fails? Someone kinks the cable while you're charging? Etc. Seems like a lot of complexity for little gain, right now anyway.

Cool though, if they can keep them as reliable as existing units.

 

[Gizmotoy]

Thinner cable actually amounts to more resistive losses. Just because they're able to make the cable thinner through liquid cooling doesn't mean that it is more efficient. Personally, I prefer the existing cables. Less to go wrong, for sure. Liquid cooled cable is neat and all, but what happens when the pump in a pedestal fails? Someone kinks the cable while you're charging? Etc. Seems like a lot of complexity for little gain, right now anyway.

Cool though, if they can keep them as reliable as existing units.

I wasn't able to listen to Elon's comments on this. Do we know if the actual wire gauge is reduced? It's entirely possible the thinner cable has the same conductive diameter and thus the same resistance. Water cooling could have simply reduced the amount of insulation required to keep the user from burning themselves on it.

Other points all seem valid. I hope the pedestal can sense when coolant isn't flowing. I've seen some weird twists in Supercharger cables over the past few years.

 

[wk057]

I wasn't able to listen to Elon's comments on this. Do we know if the actual wire gauge is reduced? It's entirely possible the thinner cable has the same conductive diameter and thus the same resistance. Water cooling could have simply reduced the amount of insulation required to keep the user from burning themselves on it.

Other points all seem valid. I hope the pedestal can sense when coolant isn't flowing. I've seen some weird twists in Supercharger cables over the past few years.

The insulation isn't just for thermal purposes, it's for conductor separation to prevent arcing between high voltage conductors.

I don't know the exact gauge of the wiring used in the original pedestals, but I assure you based on the images of the Mountain View cables that they are not the same size.

 

[jjkroll]

The insulation isn't just for thermal purposes, it's for conductor separation to prevent arcing between high voltage conductors.

I don't know the exact gauge of the wiring used in the original pedestals, but I assure you based on the images of the Mountain View cables that they are not the same size.

I would assume they are using a non-electrically conductive liquid for cooling, which could potentially provide better protection than the rubber insulation. This could also be a mostly passive system with just thermal conductive heat transfer. Not necessarily a pump/flow based system. Just like a heat pipe based heatsink in a laptop. Someone needs to supercharge when it is hot and listen for a pump or fan in the pedestal.

 

[wk057]

I would assume they are using a non-electrically conductive liquid for cooling, which could potentially provide better protection than the rubber insulation. This could also be a mostly passive system with just thermal conductive heat transfer. Not necessarily a pump/flow based system. Just like a heat pipe based heatsink in a laptop. Someone needs to supercharge when it is hot and listen for a pump or fan in the pedestal.

The liquid wouldn't be in direct contact with the conductor's metal for sure.

I would be very impressed if this is a passive system, however I highly doubt it. We're talking about potentially dissipating hundreds of watts per foot of cable. This is an active system (pump, radiator, etc) with 99% certainty.

I have a water cooled PC that dissipates ~1kW. It takes about 3.2L/min of flow and a ~6x18" radiator with multiple fans to keep the water temperature < 40C.

 

[jjkroll]

The liquid wouldn't be in direct contact with the conductor's metal for sure.

I would be very impressed if this is a passive system, however I highly doubt it. We're talking about potentially dissipating hundreds of watts per foot of cable. This is an active system (pump, radiator, etc) with 99% certainty.

I have a water cooled PC that dissipates ~1kW. It takes about 3.2L/min of flow and a ~6x18" radiator with multiple fans to keep the water temperature < 40C.

Of course, I believe you are correct. Now you have me thinking about how much power dissipation there is in that roughly 6-8 feet long cable. Sounds like a quick and fun weekend project to design a liquid cooled supercharger cable, at least on paper.

 

[Cottonwood]

Of course, I believe you are correct. Now you have me thinking about how much power dissipation there is in that roughly 6-8 feet long cable. Sounds like a quick and fun weekend project to design a liquid cooled supercharger cable, at least on paper.

Take a look at American wire gauge - Wikipedia, the free encyclopedia

Let's do a guesstimate. Make a wild guess that the copper in the new cables is #4 copper, which has a resistance of 0.2485 mOhm/ft. If the total length of the cable is 5 feet, so out and back is 10 ft, that is 2.485 mOhm total. Peak current is 330 Amps. Power is i^2*R or 330^2*0.002485 or 270 Watts total dissipation. Every wire gauge smaller is about 20% more power in the wires, so 300 Watts is in the ball park.

About 300 Watts lost out of 120 kW transferred is only 0.25% loss, not bad.

 

[TEG]

They could have a micro power generator recapture some of the energy from the waste heat! Maybe just a Peltier device to help power the coolant pump?

 

[wk057]

The HPWC has #6 wire I believe, and folks are saying this is thinner.

As for peltier.... they're so inefficient they're effectively useless for power generation.

 

[jjkroll]

Take a look at American wire gauge - Wikipedia, the free encyclopedia

Let's do a guesstimate. Make a wild guess that the copper in the new cables is #4 copper, which has a resistance of 0.2485 mOhm/ft. If the total length of the cable is 5 feet, so out and back is 10 ft, that is 2.485 mOhm total. Peak current is 330 Amps. Power is i^2*R or 330^2*0.002485 or 270 Watts total dissipation. Every wire gauge smaller is about 20% more power in the wires, so 300 Watts is in the ball park.

About 300 Watts lost out of 120 kW transferred is only 0.25% loss, not bad.

Thanks. You beat me to it. I had just done this before checking back here. Now I just need to look at a model for thermal conductivity of copper wire gages to see if this could just be a liquid cooled heatsink attached to the wire in the pedestal. The copper wire itself could be conducting the heat back to the cooler heatsink.

 

[TEG]

...to see if this could just be a liquid cooled heatsink attached to the wire in the pedestal. The copper wire itself could be conducting the heat back to the cooler heatsink.

Some mention of that back thread here:
Supercharger - Mountain View, CA (Went LIVE on 06-09-2015) - Page 12

 

[Matias]

The HPWC has #6 wire I believe, and folks are saying this is thinner.

As for peltier.... they're so inefficient they're effectively useless for power generation.

IIRC BMW has been able to extract few hundred watts from 700 C car exhaust pipe which conveys several ten kilowatts heat energy. So they are ineffective.

If they were more effective, they would be beneficial in electric car to recover engine coolant energy. Maybe some day.

edit:

http://en.wikipedia.org/wiki/Automotive_thermoelectric_generator

 

[aronth5]

Today we're assuming copper wiring but is there any chance that in the next 5-10 years Tesla might be able to use some type of high conductivity carbon wiring?
Just like new battery technology articles get published with lots of hype but commercializing advancements is always the hardest to accomplish so most end up going no where.
Is this likely to be the same scenario for carbon wiring or some other replacement wiring for copper?

 

[hbouw]

Not sure whether this has already been stated but wouldn't Tesla's main interest in these new cables be a lower copper cost and lower likelyhood of them getting stolen for the copper content?

Would be interesting to learn how much $$$-saving in copper the new cables give. Do these new cables run all the way to the charger or just to the pedestal?

 

[wk057]

Not sure whether this has already been stated but wouldn't Tesla's main interest in these new cables be a lower copper cost and lower likelyhood of them getting stolen for the copper content?

Would be interesting to learn how much $$$-saving in copper the new cables give. Do these new cables run all the way to the charger or just to the pedestal?

Definitely not saving anything here. The new cable and it's added components are more expensive than the original cables, with 100% certainty. Copper wire isn't all that expensive, especially when we're talking about ~6'. A cooling pump, radiator, etc is most definitely more expensive than the difference in wire cost.

 

[Cosmacelf]

Would be interesting to learn how much $$$-saving in copper the new cables give. Do these new cables run all the way to the charger or just to the pedestal?

The point of them isn't cost savings (if there is any), it is to make the cable easier to use, so running them underground in a conduit to the SC cabinet wouldn't buy you anything. But to definitively answer, did anyone snap pictures of the mountain view location construction?

 

[DouglasR]

Maybe there should be a separate thread on liquid-cooled cables?

 

[GasDoc]

Here's how supple the cable is

3pm Friday. 7 out of 12 spots taken.

Spot 3B is attractive because 3A is designated handicap use and the sign says to "use last"

 

[markb1]

Spot 3B is attractive because 3A is designated handicap use and the sign says to "use last"

Here in San Diego, the "use last" sign seems to be often ignored.