I feel like I have gone down a rabbit hole and came out knowing nothing. I understand this is a really basic question. My son and I are building a simple RC. It is using 4 1.5v (AAA) batteries in series. So if what I have gathered is correct that is 6v. What I cannot seem to figure out is what size wire should I get. I honestly thought this would be in the spec of the wire. Maybe I am not seeing it. I need a pretty good length and want to make sure before I go off and buy this.

I know there has to be a formula for this but what I am googling is not turning it up.

  • \$\begingroup\$ It is not because it is affected by how hot the ambient temperature is, the cooling air flow of the wire, and surrounding wires (other heat sources) and the insulation material's max temp. The formula is a nasty super physics differential equation. Just use a table made for not too abnormal environmental conditions. Or just use 22AWG wire because AAA batteries are too weak to put out a lot of current anyways. How long a length? Wire heating up because wire is too small and losing voltage over a long length because it is too small are two different things. \$\endgroup\$
    – DKNguyen
    Jan 22, 2020 at 1:54
  • \$\begingroup\$ Wire size is dictated by current and allowable temperature rise. There are lots of questions about this already. electronics.stackexchange.com/q/122351/2028 electronics.stackexchange.com/q/389832/2028 electronics.stackexchange.com/q/386782/2028 \$\endgroup\$
    – JYelton
    Jan 22, 2020 at 2:00
  • \$\begingroup\$ @DKNguyen Around 5-7 ft. The car is connected via the wire so needs some room to move. \$\endgroup\$
    – nerdlyist
    Jan 22, 2020 at 2:32
  • \$\begingroup\$ @JYelton I am sure it does if I was not just getting started on this adventure. I rember why I went computer science over electrical engineer now. \$\endgroup\$
    – nerdlyist
    Jan 22, 2020 at 2:35
  • 2
    \$\begingroup\$ I'll toss out another weird bit of trivia. Each gauge change (say, going from #20 to #21) is 1 dB. So 6 gauges means 4 times or one-quarter, up or down. #10 is \$1\:\frac{\text{m}\Omega}{\text{ft}}\$. So #16 is \$4\:\frac{\text{m}\Omega}{\text{ft}}\$. It's pretty easy to remember and work around things from this simple rule of thumb and one memorized benchmark. \$\endgroup\$
    – jonk
    Jan 22, 2020 at 7:55

1 Answer 1


normally I solid grab some scrap wire and see how it goes.

For AAA current will probably be less than 1A so AWG29 or fatter should be fine


I'm looking at the chassis wiring column.

I would use AWG24 salvaged from an old ethernet patch cable (because I gave lots of that here)

  • \$\begingroup\$ Well you at the least saved me money. I have spools of Ethernet cord to try out! That chart is helpful at least in pointing in what I need to understand a little better. \$\endgroup\$
    – nerdlyist
    Jan 22, 2020 at 2:36

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