Charging Question

[anewbe]

Okay you Gurus, I know you got the answer. I got the same type of charger at home as I do at the office. At home I peak charge at 17+ KW but at the office I always peak charge at 14.6 KW. Exactly the same type of charger. Why the difference?

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[B177y]

Identical chargers, we'll use two identical Emporia hard-wired 48 amp EVSE for an example, can both be set at different output levels.

The Emporia at your house can be on proper size wire and circuit so that it is able to be set at the full 48 amp output (11.5 kW).

The Emporia at your work can be on smaller wiring and a smaller circuit and will be set at 32 amp output (7.7 kW).

Identical chargers, set to different outputs.

 

[anewbe]

Identical chargers, we'll use two identical Emporia hard-wired 48 amp EVSE for an example, can both be set at different output levels.

The Emporia at your house can be on proper size wire and circuit so that it is able to be set at the full 48 amp output (11.5 kW).

The Emporia at your work can be on smaller wiring and a smaller circuit and will be set at 32 amp output (7.7 kW).

Identical chargers, set to different outputs.

So you are telling me that the charger (Ford) can determine the wire size coming from the panel?

 

[SpaceEVDriver]

The EVSEs were set to a maximum amperage by the installer (or should have been) based on the circuit ampacity. There's typically a mechanical switch that allows the installer to set the maximum amperage the EVSE will pull from the grid. Sometimes it's a software setting.

Based on the information you've given us, the settings are:
Work: 14.6 kW / 240 volts = 60 Amps.
Home: 17 kW / 240 volts = 70 Amps.

Your home EVSE should be on a circuit that can handle at least 90 Amps and your work EVSE appears to be on a circuit that can handle at least 75 Amps. At least if they were installed correctly that's what they're on.

 

[B177y]

The installer determines the wire and circuit size based on the capacity available in the electrical service panel. The customer can also determine the wire and circuit based on how much they are willing to spend on the installation. Anything is possible with the proper amount of money and resources....

My guess would be if the charger at your work location, assuming it is the identical model and capacity as your home charger (may look the same but still be different models), is on a smaller circuit and is set to a lower output.

Your work location may also be on commercial 3-phase power, which would deliver 208 volts vs your home charger which is on 240 volt. In this case, even if the chargers are both on 60 amp breakers, the kW output will be different:

240 volt x 48 amp = 11,520 watts (11.5 kW)
208 volt x 48 amp = 9984 watts (~10 kW)

Edit-

@SpaceEVDriver seems to have better math.

Edit 2-

Using his numbers seems to show that both chargers could be 70 amp chargers:

17,000 / 240 = 70.83 amps
14,600 / 208 = 70.19 amp

They could be identical installs but have 240 volt at home and 208 at work.

 

[Maquis]

The EVSE sets the amps, not the KW. Most commercial locations have 208V while you have 240 at home. The numbers you are seeing just happen to exactly match the ratio of 208/240!

Edit….sorry, already covered in post 6.

 

[Heliian]

identical installs but have 240 volt at home and 208 at work.

Ding ding ding, you nailed it. Even residential voltage can vary from 220-250v.

 

[Maquis]

Ding ding ding, you nailed it. Even residential voltage can vary from 220-250v.

If the utility is in compliance with ANSI C84.1, the voltage should be between 228 and 252 under normal circumstances. I think that’s at their transformer. If mine was as low as 220, I’d start being concerned.

 

[Heliian]

If the utility is in compliance with ANSI C84.1, the voltage should be between 228 and 252

IF. have a look at your electric company's terms of service. It's quite shocking! No pun intended.

 

[RickLightning]

Okay you Gurus, I know you got the answer. I got the same type of charger at home as I do at the office. At home I peak charge at 17+ KW but at the office I always peak charge at 14.6 KW. Exactly the same type of charger. Why the difference?

The installer determines the wire and circuit size based on the capacity available in the electrical service panel. The customer can also determine the wire and circuit based on how much they are willing to spend on the installation. Anything is possible with the proper amount of money and resources....

My guess would be if the charger at your work location, assuming it is the identical model and capacity as your home charger (may look the same but still be different models), is on a smaller circuit and is set to a lower output.

Your work location may also be on commercial 3-phase power, which would deliver 208 volts vs your home charger which is on 240 volt. In this case, even if the chargers are both on 60 amp breakers, the kW output will be different:

240 volt x 48 amp = 11,520 watts (11.5 kW)
208 volt x 48 amp = 9984 watts (~10 kW)

Edit-

@SpaceEVDriver seems to have better math.

Edit 2-

Using his numbers seems to show that both chargers could be 70 amp chargers:

17,000 / 240 = 70.83 amps
14,600 / 208 = 70.19 amp

They could be identical installs but have 240 volt at home and 208 at work.

240 x 80 x 93% = 17.9kW
208 x 80 x 93% = 15.5kW

 

[Maquis]

IF. have a look at your electric company's terms of service. It's quite shocking! No pun intended.

I know. It varies by state. The Illinois Commerce Commission is the utility regulator here. They give utilities the “right” to deviate +-10%. Some of the first Mach-Es sold in the Chicago area couldn’t be charged at home because Com-Ed was supplying 256-260V to a lot of areas. Users called the utility and we’re basically told to “pound sand.” Ford eventually updated the charging software to accommodate the higher voltage.

 

[B177y]

240 x 80 x 93% = 17.9kW
208 x 80 x 93% = 15.5kW

RickMath FTW!

 

[chl]

Okay you Gurus, I know you got the answer. I got the same type of charger at home as I do at the office. At home I peak charge at 17+ KW but at the office I always peak charge at 14.6 KW. Exactly the same type of charger. Why the difference?

Perhaps it is a difference in voltage supplied to the chargers?

A longer run of wire will drop more volts along the way but not enough to account for the difference.

The power supplied is the product of the voltage and the current.

Since the J1772 signals exchange information about how much the on-board charger can handle and how much the EVSE can supply, if the voltages are different the peak power would be different for the same current.

It seems like 80A current would be the EVSE max, so a difference in voltage would account for the different charge rate/power allowing for some losses along the way.

At home your voltage is probably a nominal 240V single phase (through a split phase service panel), but many/most industrial installations have a 208V three-phase service.

My wife makes pottery.
She has a kiln she used to use at a warehouse converted to a pottery studio and there the voltage was 208V.

When I built her an out building (she-shed) we wired it up to the house via a split phase sub-panel. At home our voltage is 240V, so we had to rewire the kiln to 240V to make the best use of it.

The Skutt kiln was made so one could easily switch between the two voltages with a kit that changed the wiring internally using a different terminal block and cord.

We retired that kiln after about 15 years use and got an L&L kiln with digital controls. Because it opens differently from the top we had to move the kiln to the nearer the middle of that back room section.

BTW, if you want to check it out, she sells her pottery on Etsy at: https://www.etsy.com/shop/GlyntPottery

She is selling off a lot of her inventory because she came down with APML type leukemia last August and during treatment doesn't have the energy to do much. The good news is it is a curable type of leukemia in 90% plus patients.

https://my.clevelandclinic.org/health/diseases/acute-promyelocytic-leukemia

But I guess I am rambling off topic again...my bad.

 

[Grumpy2]

Ha! Thanks for posting that photo. We had two kilns for years, and still have the largest hidden away in the garage ... your photo makes me wanting to get back to it. But I would have to push the Lightning out of the garage

 

[chl]

Ha! Thanks for posting that photo. We had two kilns for years, and still have the largest hidden away in the garage ... your photo makes me wanting to get back to it. But I would have to push the Lightning out of the garage

Well building the shed was our solution to the space issue, we considered converting the small attached one-car garage, but then we read about someone who had a kiln fire and said nope.

There are lots of plans for sheds on line for free. The shed structure cost about $1000 and was put up by one guy in one day! It amazed me so much I said "I could do that!" So I built a second shed for my tools etc. a year later (2001).

The electrical contractor we hired (I was still working in patents full time then) dug a trench from the house to the shed and installed a panel and wiring, one overhead light, outlets, roughed in before we put on drywall. But get this - he mixed up one of the hots and the neutral! I plugged in a drill to screw in drywall and POW! The drill burned up. Seems it preferred 120V to 240V. I check the outlet voltage and sure enough, 240V.

When I called them to come back they were shocked (pun intended). His supervisor explained that he had been engaged and his fiancee had an affair with his best friend. OK, but somebody could have died!!! Anyway, besides that mix up they also didn't do the required inspection so 16 years later, someone called the county because they didn't like me using my backyard, and we found out no inspection had been done. No problem, just $$ to have it done 16 years later.

There are all kinds of codes about sheds, too, but I was up on those and we were in compliance, but they did come out 3 times to check - aren't neighbors the best? Put up a privacy fence after that with no trespassing signs too. OMG. Civilization!

But that isn't the end of the story, unfortunately. About a year ago, a 120V outlet began only working intermittently and a breaker kept popping now and then. Upon doing a continuity test I discovered a the hot wire was not continuous. I had to cut open the drywall to find the location of the break. It was a wire staple the electrician had pounded into a 2x4 too hard. Guess he was angry about something? Lots of fun fishing the new wire from the outlet wall to the other wall where the panel was.

There is always something.

At least he knew not to bond the neutral in the shed sub-panel. Some electricians forget that.

We donated the old kiln to a school to use for their arts program.

I can't get my Lightning into my garage without taking out a lot of "stuff" and folding the mirrors too probably, so it lives in my driveway or on the street where my 2001 Ranger used to live.

Anyway, you should definitely think about firing up your old kiln in a shed maybe. Or in the back of the Lightning? Just kidding.

Selling on Etsy makes it a lot easier than traveling around to shows lugging stuff. Yes they cut into the profit a bit, but seems to be worth it.

Take care!

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