Amps Draw and Voltage Drop Question 2

Gdetrailer wrote:
Will draw slightly MORE current due to less voltage drop, results in motor spinning a bit faster.

RV furnace motor is a DC motor, DC for practical intents can be considered like a resistor since you are not dealing with impedance/inductance like you do with AC devices.

If you want the furnace motor to draw less current, you would need to REDUCE the voltage going to the motor. However, that results in less RPMs for the fan which results in less air flow which results in possibility of overheating the furnace and/or creating a fire hazard..

Lights dim with lower voltage and also draw fewer amps when dimmed, so that fits.

Slower fan speed in the furnace with lower voltage would get to the point the sail switch would open, so that is the safety there.

My 8531 older furnace says the 12v to it should not be above 13.5v. That is in the manual's section about the flame sensor's microamps, but I can't find a minimum voltage specified for when the blower fan gets too slow.

The furnace does work ok when battery charging is happening and the battery voltage is above 13.5v. I have not measured for voltage at the furnace then. Doug R and the other techs here would know about all that.
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Part 2--

Not sure it is the same thing for how amps work--I am now looking at the DC-DC charger

With the input of that thing, you must use fatter wire to the battery to keep the amps down and the voltage up.

Could relate to the point made above re wasted amps making heat with voltage drop? Fatter wire means the alternator does not have to do extra amps to make that heat?