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1600 kW service, 3400 Amp conductors;

herding_cats

herding_cats

Senior Member
Location
Kansas
Occupation
Mechanical Engineer
Ok so the bridge rectifier is rated for this. It charges two trucks. But each charging port has only one cable. So two charging stations for each rectifier.
 
W

winnie

Senior Member
Location
Springfield, MA, USA
Occupation
Electric motor research
How does the cost of the generator compare to the cost of the battery?

What is the spool up time of the generator?

How do fuel costs for the generator compare to electricity costs for the battery?

My thought is that the direct 1600 kW grid connection makes the most sense for high usage (full power > 33% of time).

The battery or genset would probably be better for less frequent usage.

Look for other value you can get from the battery or genset; eg backup power for the truckstop or grid voltage support.

Jon
 
T

texie

Senior Member
Location
Fort Collins, Colorado
Occupation
Electrician, Contractor, Inspector
herding_cats said:
We’re just trying to get this to make sense to the truck stop chain. They don’t see the grid connection usable to them, because of the demand charge costs. And who pays for the half-million $$ battery bank?

Another problem is what does the truck behind you do if you charge in front of them and you drain the battery from the charging station. ??

What then?

right. I’m rusty. I’ve spent the last 12 years developing low volt HVAC controls. But yes I forgot about the square root of 3. The Tesla data sheet did not list any amperage. Only 480vac
1,600 kW
Click to expand...
You also need to realize that you can't use KW for calculating the supply equipment. You need to be using input KVA as that is what the supply equipment sees as I'm sure this will not be a unity PF load. Surely Tesla must specify the supply the ampacity of the supply side. In addition the code requires the supply equipment to be rated at 125% of the input amps.
 
kwired

kwired

Electron manager
Location
NE Nebraska
Occupation
EC
So if this is powered by multiple sources, utility, on site generator, battery... seems best design would be having a common DC bus and each source only supplies whatever it it capable of to that bus and not necessarily total output capacity. If you want utility to be able to handle full 1600kW then it needs the large service mentioned. If you only want the utility to be able to provide say 50% of capacity then you could get by with smaller service and smaller rectifier. IMO multiple rectifiers would be a good idea. You could isolate a failed one and continue to use the other instead of total failure of this source.

The alternate sources also kind of presumes you are depending on different ones depending on conditions and/or cost of operating a particular source above a certain level -- like avoiding demand charges from POCO.

The battery I see as more of a "surge tank". Like having a large water tank that allows you to fill some other vessel rather quickly where the normal water supply can not deliver that kind of volume that quickly yet there is enough time between fills for it to recover before the next fill.
 
herding_cats

herding_cats

Senior Member
Location
Kansas
Occupation
Mechanical Engineer
Right. I thought that was weird that there was no kVA rating or amperage. The data sheet I got was from an “engineer-reporter” guy that works for a engineering and technology magazine. It didn’t come from Tesla direct. I’m still waiting on that.

This whole project started about 10 days ago. If you read the news about it, you see clearly that the folks reporting on the Tesla semi truck know nothing about how power/billing work.

For instance in one article the guy gets the average kWh number from Pacific Power at .13 cents, then divides the claimed kWh usage of the truck and is enthralled with this “extremely inexpensive” method for truck charging/traveling, unaware of the $20,000 per month demand charge that comes with it. Ratcheting / revolving demand charges are a huge barrier for the cyber truck and the semi truck.

And depending where you get your info from, the numbers are all over the place regarding costs, time to charge, differences between level 2 and level 3.
Additionally the EVs built starting about 10 years ago owners were fed very inaccurate information about realistic charging times and duration, mileage, degradation of the battery.
 
Last edited by a moderator:
herding_cats

herding_cats

Senior Member
Location
Kansas
Occupation
Mechanical Engineer
kwired said:
So if this is powered by multiple sources, utility, on site generator, battery... seems best design would be having a common DC bus and each source only supplies whatever it it capable of to that bus and not necessarily total output capacity. If you want utility to be able to handle full 1600kW then it needs the large service mentioned. If you only want the utility to be able to provide say 50% of capacity then you could get by with smaller service and smaller rectifier. IMO multiple rectifiers would be a good idea. You could isolate a failed one and continue to use the other instead of total failure of this source.

The alternate sources also kind of presumes you are depending on different ones depending on conditions and/or cost of operating a particular source above a certain level -- like avoiding demand charges from POCO.

The battery I see as more of a "surge tank". Like having a large water tank that allows you to fill some other vessel rather quickly where the normal water supply can not deliver that kind of volume that quickly yet there is enough time between fills for it to recover before the next fill.
Click to expand...
Yup. Our solution uses only 120vac 2 amp control power to keep the charger screens activated and can operate with the turbine off. Turbine supplies 50kW and up too 2000kW.

kwired- Tesla built yhir own battery and grid management system so yes good ideas that’s exactly what they did. But I’m pretty sure about the single bridge rectifier they specified that.
 
herding_cats

herding_cats

Senior Member
Location
Kansas
Occupation
Mechanical Engineer
Look into the charging data for the cyber truck and the semi. It starts to not make sense or add up.
 
W

winnie

Senior Member
Location
Springfield, MA, USA
Occupation
Electric motor research
herding_cats said:
For instance in one article the guy gets the average kWh number from Pacific Power at .13 cents, then divides the claimed kWh usage of the truck and is enthralled with this “extremely inexpensive” method for truck charging/traveling, unaware of the $20,000 per month demand charge that comes with it. Ratcheting / revolving demand charges are a huge barrier for the cyber truck and the semi truck.
Click to expand...

Again that factors into utilization.

If the truck charges at 1MW at $0.13 per kWh, that is $130 per hour in electricity.

If there are 20 one hour charges per day, 30 days a month, then the demand charge is another 25%; serious nut not a deal breaker.

If you get 2 charges per week, that demand charge wipes you out.

Jon
 
herding_cats

herding_cats

Senior Member
Location
Kansas
Occupation
Mechanical Engineer
Get this: Tesla claims it can charge at full rate in 30 min? At the 1MW DC charge port.

Again, the electrical utility demand charge doesn't match the demand of charging. They (Tesla) have hit a wall. That's why we went with displaced power generation. Using natural gas, and it's already there piped into the building. Pacific Power actual total demand charge is around $15.50. Even at 1000 kW that's $15,500 per month plus all the kWh charges, taxes, fees.... You would need electric trucks lined up bumper to bumper all day to even start to have this make sense... and that's not happening anytime soon.
 
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