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I defined my argument as 40x 350kW. Sure that is peak, but it's still pretty impressive? I know they won't all be running flat out, and that is why I said ROI on a poorly utilised setup like that won't be high?

But going from the physical sizes of those two transformers sitting there they are at least 3.5MW to 4MW each. Thats 7 - 8MW total plus megapack capacity. I have a 2.5MW transformer sitting in my backyard connected to our power station and ours isn't as big by far.

On ROI: if 40 stalls are full 10 hours of the day and are charging at 75kW average as you say, and Tesla charges $0.10c premium on every kWh of electricity charged you get $3000 a day or a $1m a year. Not really that great given that it's fairly unlikely to run at that rate.

Do you have any figures on Capex? $5-7m seems about right? $1m for Megapack, $1.75m for the SC units alone, network connection, switchgear transformers another $1m, thats nearly $4m and you still have to do all the roads, stalls, solar, siteworks, planning, approvals, labour and property itself etc. Thats best case 20%, but more likely around 10% ROI. That wouldn't be getting me out of bed in the morning. My last project was 370% over 4 years. :unsure:

The comment about v4 allowing other brands to charge makes me think utilisation rate is in fact a problem.
First, I didn’t say average charge speed would be 75 kW. I said half the cars would be charging at 75 kW or less. Thinking on it, that is… probably a bit low. More likely half would be at 100 kW. If you just plug in a destination and follow Tesla’s recommended charging stops, they get you to stops at around 20% and have you leave at a bit below 80% and most stops take 15-20 minutes. At a 250 kW charger, thats when tapering starts and your rate of charge starts going down.

After 5 minutes you are at 50% state of charge and your charge rate is down to 150 kW. After 10 minutes you are at 62% SOC and charging at around 100 kW. After 15 minutes you are at 70% SOC and charging at 75 kW.

I think you get the point. Supercharger stations are not designed to operate at peak capacity continuously. V2 chargers would share 150 kW between them. Every V3 chargers are grouped in 4s and have a similar, but more generous maximum draw which is lower than the peak draw rate. (Numbers are approximate)

Charge curves make this all work; the assumption is that someone on the circuit will be at least halfway through their charge cycle.

1663040361227.png


Since you never have 40 people roll into an empty station at once, it works.

 
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nah. takes up too much room. you just need 2 or 3 pull-through's for every dozen regular stalls.
Maybe I’m not being clear, cause it’s simple.

just remove the center parking block and allow pull throughs like that.
 
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Maybe I’m not being clear, cause it’s simple.

just remove the center parking block and allow pull throughs like that.
I’d love to see a drawing of a station where you could get 40 pull through stalls on the same real estate as this design. The transformer boxes need to be within a handful of feet of the stations so you’d need to squeeze those in as well.

I’d be surprised if you could get 25 on this same lot.
 

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We are lucky here in Australia,

Most charging stations have 2 stalls , a few even have 6 !!!!!

:p
 


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First, I didn’t say average charge speed would be 75 kW. I said half the cars would be charging at 75 kW or less. Thinking on it, that is… probably a bit low. More likely half would be at 100 kW. If you just plug in a destination and follow Tesla’s recommended charging stops, they get you to stops at around 20% and have you leave at a bit below 80% and most stops take 15-20 minutes. At a 250 kW charger, thats when tapering starts and your rate of charge starts going down.

After 5 minutes you are at 50% state of charge and your charge rate is down to 150 kW. After 10 minutes you are at 62% SOC and charging at around 100 kW. After 15 minutes you are at 70% SOC and charging at 75 kW.

I think you get the point. Supercharger stations are not designed to operate at peak capacity continuously. V2 chargers would share 150 kW between them. Every V3 chargers are grouped in 4s and have a similar, but more generous maximum draw which is lower than the peak draw rate. (Numbers are approximate)

Charge curves make this all work; the assumption is that someone on the circuit will be at least halfway through their charge cycle.

1663040361227.png


Since you never have 40 people roll into an empty station at once, it works.
Thanks for the graph. I've talked to Adjelange about this a few times. He always liked to say that all Teslas charge at 1C from 0-100% SOC. Shame he's not around much anymore.

Anyways do you have a link to a source for more charge rate graphs on different models? I'm doing some calculations to see what the average charge rate is on each.

I've been hearing that the charge cable connector is doing the throttling as it temperature derates when it gets warm. A wet rag helps... dunno sounds a bit dodgy that that is a problem at all.
 

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A single pull-through slot seems so odd. Just a bit North of there on I-10, the new V3 has 3+ pull-through chargers.
 
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A single pull-through slot seems so odd. Just a bit North of there on I-10, the new V3 has 3+ pull-through chargers.
If the charger is on the way to a lake maybe 5 trailer charging spots makes sense. Along a random stretch of highway, 1 might be plenty. Not sure how much Tesla thinks about this specific case. Might just boil down to space available or what the company leasing the land wants.

If you are running a truck stop, maybe you really want those trailers with longer charging times?
 

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Lake? So you've never noticed how many travel and toy trailers go between San Diego and AZ > beyond? My reason for a CT is for toys and our travel trailer.
 
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Thanks for the graph. I've talked to Adjelange about this a few times. He always liked to say that all Teslas charge at 1C from 0-100% SOC. Shame he's not around much anymore.

Anyways do you have a link to a source for more charge rate graphs on different models? I'm doing some calculations to see what the average charge rate is on each.

I've been hearing that the charge cable connector is doing the throttling as it temperature derates when it gets warm. A wet rag helps... dunno sounds a bit dodgy that that is a problem at all.
I’m not sure where the best place to get data on charging curves is. I just dug around a bit to find one. It is something which is surprisingly under-tested on vehicles.
 


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One pull through for trailers is likely enough in most areas, but it would be smart to always have at least 2 for future proofing. I will be towing with my CT 2-4 days every month.
 
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One pull through for trailers is likely enough in most areas, but it would be smart to always have at least 2 for future proofing. I will be towing with my CT 2-4 days every month.
If they have 1 for every charging station and charging stations reliably every 50 miles, it could work. Right now they don’t even have enough charging station locations so maybe they should add 2 in each location. Of course that means eliminating at least 1 non-pull through stall.
 

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charging stations reliably every 50 miles, it could work. R
That is a good point. If we had a pull-through every 50 miles 1 would probably be enough. In my specific situation, I am often towing a cargo trailer and traveling with someone else towing an RV trailer, so I would nearly always need 2 pull-through stalls to avoid unhooking.
 

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I've been hearing that the charge cable connector is doing the throttling as it temperature derates when it gets warm. A wet rag helps... dunno sounds a bit dodgy that that is a problem at all.
The lithium cells will produce more heat with higher SoC, so input power is throttled. The charge cable can also overheat, but that can happen at any SoC.

I suppose a clever person could cool the cable sensor and trick it into overheating for a faster charge, but that sounds dangerous while holding it by a wet rag.
 

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If they have 1 for every charging station and charging stations reliably every 50 miles, it could work. Right now they don’t even have enough charging station locations so maybe they should add 2 in each location. Of course that means eliminating at least 1 non-pull through stall.
Probably would lose three stalls.

Of course, you could set it up so that each pull-through stall has two chargers - I think they do this in Europe - so depending upon the mix of traffic, you could have better utilization.

-Crissa

 

 
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