Up until today I've been blaming getting reduced from 30A to 22A on Chargepoint EVSE's to their crappy hardware. Although I think the latter is still true, I now believe Tesla is to blame, not Chargepoint.
The car will reduce charging current whenever the voltage drop from start of charging exceeds 8%. Chargepoint does not specify wiring recommendations in their installation manual, however NEC code seems to recommend (not require??) a maximum of 5% voltage drop. So an electrician wiring up one of these EVSE's could (and it seems almost always does) leave the wiring at 5% voltage drop under load, and it would be a perfectly OK installation.
What does this mean in real life? Well it means for most installations, the service voltage can't drop by more than 3%, or your Tesla goes into reduced charging current. It's even worse than that, because there's usually 25 feet of the J1772 cord, which also has voltage drop. I just measured the station I was plugged into, and the actual voltage drop from 0A to 30A is 6.77%. Which explains why it often drops to 22A, small normal fluctuations in service voltage are enough to trigger Tesla's algorithm. So now I babysit it, and as soon as I see 22A, I stop and start charging, hoping that the new lower starting voltage will hold it for a while, and it usually does if timed properly.
This seems like another thing to add to the list of feature/functionality rolls backs attributed to CYA.
The car will reduce charging current whenever the voltage drop from start of charging exceeds 8%. Chargepoint does not specify wiring recommendations in their installation manual, however NEC code seems to recommend (not require??) a maximum of 5% voltage drop. So an electrician wiring up one of these EVSE's could (and it seems almost always does) leave the wiring at 5% voltage drop under load, and it would be a perfectly OK installation.
What does this mean in real life? Well it means for most installations, the service voltage can't drop by more than 3%, or your Tesla goes into reduced charging current. It's even worse than that, because there's usually 25 feet of the J1772 cord, which also has voltage drop. I just measured the station I was plugged into, and the actual voltage drop from 0A to 30A is 6.77%. Which explains why it often drops to 22A, small normal fluctuations in service voltage are enough to trigger Tesla's algorithm. So now I babysit it, and as soon as I see 22A, I stop and start charging, hoping that the new lower starting voltage will hold it for a while, and it usually does if timed properly.
This seems like another thing to add to the list of feature/functionality rolls backs attributed to CYA.