Newly installed HPWC: correct voltage?

[Anzir]

I had a new HPWC installed on a 100 Amp breaker at my office. When I got the switches set correctly and turned the unit on, it ramped up to charging at 15kw, 72 Amps, at 208V. The voltage suprised me. Shouldn't that be closer to 240? At home my mobile charger pulls 6kw, 32 Amps at 236V off a NEMA 14-50 on a 50 Amp breaker.

 

[TexasEV]

Commercial power is often 208V, not 240V.

 

[swaltner]

Yep, commercial power is typically three-phase. The image below shows two of the three phases over time and then phase1-phase2. With each phase being "120 degrees out of phase" or however you want to say it, you get the 208 V difference when you go L1-L2, L2-L3, or L3-L1.

 

[RandyS]

3-phase commercial power and the feeds to some condos / high rises, etc. is usually 208 volts phase to phase and 120 volts phase to neutral. It is good that the voltage didn't sag below 208 when you charged at that current level...

 

[Anzir]

Thanks fellas. Last question: I plan to offer charging as a benefit (perk) for people who come to my office for treatment, only during the day. I turn the breaker for the HPWC off when I leave the office so that I don't get any freeloaders charging at night. My question is, can I plug my X into the HPWC first, then turn the breaker on inside when I arrive at the office, or is that bad for the wall connector?

 

[Fiver]

Thanks fellas. Last question: I plan to offer charging as a benefit (perk) for people who come to my office for treatment, only during the day. I turn the breaker for the HPWC off when I leave the office so that I don't get any freeloaders charging at night. My question is, can I plug my X into the HPWC first, then turn the breaker on inside when I arrive at the office, or is that bad for the wall connector?

Shouldn't cause any harm, but out of caution I might wait to plug in after the HPWC has powered up.

 

[eprosenx]

Thanks fellas. Last question: I plan to offer charging as a benefit (perk) for people who come to my office for treatment, only during the day. I turn the breaker for the HPWC off when I leave the office so that I don't get any freeloaders charging at night. My question is, can I plug my X into the HPWC first, then turn the breaker on inside when I arrive at the office, or is that bad for the wall connector?

Plugging in first before turning on power to the Wall Connector won’t hurt the Wall Connector, however, it might not be fantastic for the Wall Connector to power up and down every day (this is super minor though). Basically when power is applied to the wall connector it boots up a small micro controller which then controls the Wall Connevtor. The wear componant in the system is the high voltage contactor which won’t engage until it talks to a connected car. Now I am unsure if a Tesla will start charging if you plug it into a “dead” wall connector and the ln power up the wall connector. I have not tried it.

I would be more worried about the number of cycles you are putting on that breaker. Typically the larger breakers are not rated for use as a “switch”. They are not intended for frequent operation. A “disconnect” switch may be more appropriate for that use case.

 

[Anzir]

Plugging in first before turning on power to the Wall Connector won’t hurt the Wall Connector, however, it might not be fantastic for the Wall Connector to power up and down every day (this is super minor though). Basically when power is applied to the wall connector it boots up a small micro controller which then controls the Wall Connevtor. The wear componant in the system is the high voltage contactor which won’t engage until it talks to a connected car. Now I am unsure if a Tesla will start charging if you plug it into a “dead” wall connector and the ln power up the wall connector. I have not tried it.

I would be more worried about the number of cycles you are putting on that breaker. Typically the larger breakers are not rated for use as a “switch”. They are not intended for frequent operation. A “disconnect” switch may be more appropriate for that use case.

Thanks for the info. I would be cycling the breaker a max of 2x a week since I'm not at that location every day. I ran that by my contractor after reading your post and he said the breaker would fatigue over time but it's not going to happen any time soon.

 

[Cosmacelf]

Yeah, I wouldn’t worry about the HPWC. I agree, the breaker is the component that is more likely to degrade over time since it isn’t rated to be used as a switch.

The other thing you can do is just not worry about it and leave it on. It isn’t THAT useful since only Teslas can charge at it and all Teslas have pretty big batteries meaning they are unlikely to be sitting there waiting for a non Supercharger location. I have a free J1772 charger at my business and have found that the only random people charging there are non Teslas that have 80 mile range, so getting 30 miles of range per hour is helpful for them.