how to calculate load for multiple EV chargers

[jdping2]

Good morning all, I have a customer that have purchased 10 electric "step vans" they look like the large UPS trucks and are all electric. Each charger ( per manufaturer) will require an 80 amp 2 pole 120/208 single phase breaker, total max load per charger is 64 amps. The customer has an available 600 amp distribution breaker in existing switchgear 120/208 3 phase , that has been designated for all of the EV chargers. I will be installing a 600 amp 120/208 distribution panel and load it up with 2 pole 80 amp breakers for the new load as well as future. All step vans will charge at off hours ( 7 pm 5 am. ) - will a 600 amp 120/208 dist. panel accept the new load? If so, what is the max amount of chargers I can feed from a 600 amp dist panel? I have no clue how to calc the load ....


Respectfully

John D

 

[winnie]

The easiest approximation is to simply take the VA of your available circuit and divide by the VA of your chargers.

Since the load is long duration, you need to treat it as a 'continuous' load and limit yourself to 80% of the supply circuit rating.

Thus: each charger is a 64A*208V = 13312 VA

Your supply circuit is 600*208*sqrt(3)*0.8 = 172928 VA (sqrt 3 because it is 3 phase, 0.8 because it is continuous loading)

So the circuit can support 13 chargers.

Now this is an approximation, in particular assumes a balanced 3 phase load. The closest number of 3 phase balanced chargers is 12, so to be safe I'd say that was the limit.

-Jonathan

 

[Dennis Alwon]

I don't understand how the grid is going to be able to keep up with this type of added loads. 600 amps 3 phase for 10 vehicles. What kind of load will we see when places like ups go all electric? 1,000,000 amps hahaha

 

[winnie]

If people expect to charge EVs anytime and anywhere they want to, then the grid won't take it.

If people expect to charge EVs during off peak hours or when there is surplus available capacity, then these loads will _improve_ grid function.

The devil is in the details.

-Jonathan

 

[retirede]

If people expect to charge EVs anytime and anywhere they want to, then the grid won't take it.

If people expect to charge EVs during off peak hours or when there is surplus available capacity, then these loads will _improve_ grid function.

The devil is in the details.

-Jonathan

And utility rate structures will evolve to incentivize off-peak charging. In many locales, they already are.

 

[jaggedben]

I don't understand how the grid is going to be able to keep up with this type of added loads. 600 amps 3 phase for 10 vehicles. What kind of load will we see when places like ups go all electric? 1,000,000 amps hahaha

Surely you are not talking about a single UPS facility that has sixteen thousand vehicles or something like that. I'm not sure I get your point exactly. I mean, on average (not peak) US grids power something like the equivalent of 2 billion amps at 208V single phase.

I'm reminded of...

 

[jdping2]

The easiest approximation is to simply take the VA of your available circuit and divide by the VA of your chargers.

Since the load is long duration, you need to treat it as a 'continuous' load and limit yourself to 80% of the supply circuit rating.

Thus: each charger is a 64A*208V = 13312 VA

Your supply circuit is 600*208*sqrt(3)*0.8 = 172928 VA (sqrt 3 because it is 3 phase, 0.8 because it is continuous loading)

So the circuit can support 13 chargers.

Now this is an approximation, in particular assumes a balanced 3 phase load. The closest number of 3 phase balanced chargers is 12, so to be safe I'd say that was the limit.

-Jonathan

Jonathan,
Thank you for taking the time to respond and I greatly appreciate the fact that you ran the calculations as well. I will not forget your generousity

Much respect
John