Amps Draw and Voltage Drop Question 2
Question 2 -17 Oct -------- There are no dumb questions--until now! If the furnace draws 8 amps and there is a 0.2v drop when it is on, and you change the positive wire to the furnace to a fatt...
Forum Discussion
Unless I’m missing something, most of responses are missing the point of the issue (as the OP might have with how he’s thinking about this).
I believe the 0.2V drop is not IR from the 8A flowing through wiring to the furnace, but instead is internal voltage drop in the batteries (assuming normal battery connection wires). OP is not measuring 0.2V drop across the wire to the furnace, but sees that drop in battery voltage. Doesn’t sound like a big battery bank, or strong (low internal resistance) batteries like Lithium or Lifeline AGMs. There is a reason that SOC is measured with resting batteries and not under load, any battery will have some voltage drop when sourcing significant current.
To answer the OP question - no, a larger wire to the furnace will not help the situation. Any small IR change by beefing up this wire would have 2nd or 3rd order trivial change in motor draw, fan speed, etc. Better batteries and/or more capacity is the issue you’re dancing around.
I believe the 0.2V drop is not IR from the 8A flowing through wiring to the furnace, but instead is internal voltage drop in the batteries (assuming normal battery connection wires). OP is not measuring 0.2V drop across the wire to the furnace, but sees that drop in battery voltage. Doesn’t sound like a big battery bank, or strong (low internal resistance) batteries like Lithium or Lifeline AGMs. There is a reason that SOC is measured with resting batteries and not under load, any battery will have some voltage drop when sourcing significant current.
To answer the OP question - no, a larger wire to the furnace will not help the situation. Any small IR change by beefing up this wire would have 2nd or 3rd order trivial change in motor draw, fan speed, etc. Better batteries and/or more capacity is the issue you’re dancing around.
