I've been living for a few weeks with the equivalent of a very long thin extension cord: a 5 amp current draw will cause a 10V voltage drop, so 2 ohms line resistance. I'm only using a short extension cord so most of that is within the walls (as it were; actually an outlet at the far end of a parking lot with a long run of wire).
If you are set for the default 12A draw, the 24V drop will take the line voltage well below the 105-125VAC operating range. Charging stops. If I use 5 to 7A draws, it will stay stable overnight--all consistent with my 119VAC no-load supply staying above 105 at the car with the load. It doesn't kick out immediately at 104, but often does during the night. I am getting 1.5 m/h charging (at 20 hours per day, about 30 miles range).
I offer the following as a procedure for those inclined toward extension cords. But the whole thing could be implemented in Tesla's firmware when a 120VAC charging session was about to begin:
A little mental arithmetic with Ohm's Law will get you there faster.
If you are set for the default 12A draw, the 24V drop will take the line voltage well below the 105-125VAC operating range. Charging stops. If I use 5 to 7A draws, it will stay stable overnight--all consistent with my 119VAC no-load supply staying above 105 at the car with the load. It doesn't kick out immediately at 104, but often does during the night. I am getting 1.5 m/h charging (at 20 hours per day, about 30 miles range).
I offer the following as a procedure for those inclined toward extension cords. But the whole thing could be implemented in Tesla's firmware when a 120VAC charging session was about to begin:
- Start charging at 5A setting (that's the minimum for some reason).
- Note the very first voltage display, when current still reads 0A, then note the V when current jumps to 5A. That's your voltage drop; divide by 5 to get the line resistance R.
- Increment load by 1A and note the reduced voltage.
- Repeat until V nears 105V.
A little mental arithmetic with Ohm's Law will get you there faster.
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