2112 wrote:
BFL13 wrote:
LittleBill wrote:
resistive loads work different, if the voltage drops, so does the load
Not sure it is the same thing now, but it is still true that when you are plugged into 15a shore power and run things in your RV, you will not pop the breaker so often if you are closer to the house and don't have such a long extension cord. Or if you change from a #14 to a #12 same length, you don't pop the breaker as much.
Isn't it the same thing when you are plugged into a generator's 15a receptacle?
What you are referring to is an inductive load such as your AC compressor and blower motor. They are trying to turn at a certain RPM. You can think of them as a constant power load due to when the voltage drops the current goes up to compensate for the lower voltage in order to maintain its speed. The motor requires a certain amount of power to maintain its torque. The high current demand of the AC causes a voltage drop across the extension cord. This is commonly referred to as IR. This voltage drop means there is less voltage at the AC. The longer the cord or the thinner the wires, the higher the IR.
A resistive load is a fixed load. When the voltage drops the current drops proportionally. One caveat to an electric heater is the coil resistance will change with temperature. It will draw slightly more current when you first turn it on. As it heats up the coil resistance goes up slightly, causing it to draw slightly less current.
Interesting, thanks. I did see that with my Kill-A-Watt running the RV fridge by itself (120v heater) Started out at 359 watts then that fell off quickly to 353 watts before I stopped.
I have seen that where amps go up while volts go down using the inverter/gen and also with the inverter on battery. I thought this was the inverter trying to maintain the watts, but now I am unclear on that from the above description--perhaps it is really the "demand" and not the inverter that makes it do that?
Also what kind of load is the converter/charger for whether the extension cord matters or not?
