Low voltage on a 208v EVSE, problem?

[KootenayEV]

I'm sitting at a public EVSE at a visitor centre which is likely a 208v power supply. Truck is reporting 48A being drawn off a Clipper Creek unit, and my truck is showing 9.1kW. Doing the math on that yields voltage of 189v. That seems like a really large voltage drop, over 9%. I've used this charger before with no ill effects, but hadn't noticed the implied voltage. (Side note: I like that my Model 3 report both voltage and amps, then it's really obvious.)

Question: will the onboard charger handle any voltage between about +-10% of the nominal voltage range it claims to work in? (e.g. 120-240v; equaling ~108v to 264v.) Or is there a discrete step range in between 120 and 240 where it doesn't like to function?

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[pc500]

I don't know but unless the rivian is reporting actual voltage I wouldn't trust computations based on amperage much. Sometimes those numbers can lie for example it might be telling you the amount into the battery and not lost due to efficiency.

 

[Dark-Fx]

Back when I was doing some testing, I could still get the polestar and Rivian to pull 48A on a circuit the polestar was registering as 107V after voltage drop. No complaints from either vehicle about the voltage being low

 

[Cosmacelf]

The car's charger has to boost whatever voltage it gets to around 350V pack voltage, and certainly it can accept 120V, so there is no reason for it to complain about 192V. And yes, I can absolutely believe the voltage sag is that bad. That 208V circuit is probably very long back to the panel, and I'd bet they didn't upsize the wire for that long run, resulting in lots of losses along the wire at 48A.

 

[Zoidz]

As mentioned above, you are assuming that the supply is 208 volts to the charger. You don’t know that. NEC allows a 3% voltage drop on a branch circuit, so it could be 202 volts. The utility may not be providing 208 volts. It’s not uncommon for the utility voltage to fluctuate throughout the day. There are losses through all of the circuitry all the way to the battery. It’s really of no value to try to reverse analyze this. If the vehicle says it is charging…… it is.

 

[KootenayEV]

Thanks for the replies - totally allayed my curiosity. Cheers.

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