I have two 14-50 plugs, one side of the garage ~50ft run. And other side ~15ft run. Both runs are 8AWG copper.
I have a J1772 charger (with a readout of Volts, Amps, Kwh etc...) and the Tesla Mobile charger. When plugged in and not pulling any power, the readout on the J1772 and On Tesla screen agree, Voltage on the line is ~241v.
I measured the voltage at the meter and for both outlets it reads 242V. Under load (when charging) this read sometimes goes down to 239V sometimes stays at 242V.
As I start the charge and AMPs ramp up to 32 on the 15ft run the car reports as charging at 237V. When charging on 50ft run it reports as charging at 235V.
It is expected that 50ft run would have bigger voltage drop (as much as 1%). However getting 235V is between 1.5% to 2.5% drop (depending on reading at the meter). To put it in perspective a 4V drop is like powering two 60W incandescent bulbs, that heat is going somewhere. The real question is though, is there really a 4v drop or is it a reporting issue.
When I use the J1772 charger on the Tesla, the Voltages reported by the car match that of Tesla charger however the charger itself is reporting 239V on the 50ft run. This is much more in line with whats expected.
This got me thinking, either both runs have issues and additionally the J1772 readout is inaccurate. I would think all those coinciding is very unlikely. Or the Tesla's Voltage reporting is inaccurate (or maybe accurate but is reported at a different stage in the electron's journey). I eliminated voltage drop at the supply (by using multimeter at the meter), so its not a supply issue.
What has your guy's experience been with the mobile charger? The unfortunate caveat is that you could be getting 245V at the meter, then if charger is inaccurate it can still show 240V charging (at 5V drop). I guess this can be verified without opening up the panel and measuring by plugging in the car, and stopping charge and seeing what voltage is reported on the line. Perhaps this is not very scientific but better than nothing.
Thoughts?
Another thought is that J1772 reports Voltage at the outlet, while I dont know at which stage Tesla report's voltage but could it be after DC conversion and therefore some loss? Could the Tesla Brick itself be eating some voltage (it has some sort of onboard electronics) and then car's electronics eating some before its reported?
One thing for sure, both J1772 and Tesla charger are providing same amount of voltage (since Tesla reports the same number on both), but Tesla's readout is at odds with J1772's readout and also at odds of the math that dictates resistance in those runs.
Would love to hear your guy's opinions.
I have a J1772 charger (with a readout of Volts, Amps, Kwh etc...) and the Tesla Mobile charger. When plugged in and not pulling any power, the readout on the J1772 and On Tesla screen agree, Voltage on the line is ~241v.
I measured the voltage at the meter and for both outlets it reads 242V. Under load (when charging) this read sometimes goes down to 239V sometimes stays at 242V.
As I start the charge and AMPs ramp up to 32 on the 15ft run the car reports as charging at 237V. When charging on 50ft run it reports as charging at 235V.
It is expected that 50ft run would have bigger voltage drop (as much as 1%). However getting 235V is between 1.5% to 2.5% drop (depending on reading at the meter). To put it in perspective a 4V drop is like powering two 60W incandescent bulbs, that heat is going somewhere. The real question is though, is there really a 4v drop or is it a reporting issue.
When I use the J1772 charger on the Tesla, the Voltages reported by the car match that of Tesla charger however the charger itself is reporting 239V on the 50ft run. This is much more in line with whats expected.
This got me thinking, either both runs have issues and additionally the J1772 readout is inaccurate. I would think all those coinciding is very unlikely. Or the Tesla's Voltage reporting is inaccurate (or maybe accurate but is reported at a different stage in the electron's journey). I eliminated voltage drop at the supply (by using multimeter at the meter), so its not a supply issue.
What has your guy's experience been with the mobile charger? The unfortunate caveat is that you could be getting 245V at the meter, then if charger is inaccurate it can still show 240V charging (at 5V drop). I guess this can be verified without opening up the panel and measuring by plugging in the car, and stopping charge and seeing what voltage is reported on the line. Perhaps this is not very scientific but better than nothing.
Thoughts?
Another thought is that J1772 reports Voltage at the outlet, while I dont know at which stage Tesla report's voltage but could it be after DC conversion and therefore some loss? Could the Tesla Brick itself be eating some voltage (it has some sort of onboard electronics) and then car's electronics eating some before its reported?
One thing for sure, both J1772 and Tesla charger are providing same amount of voltage (since Tesla reports the same number on both), but Tesla's readout is at odds with J1772's readout and also at odds of the math that dictates resistance in those runs.
Would love to hear your guy's opinions.