If the current is increased these effects will be worse. The voltage loss increases, and the cable heats up more.
This is how to calculate the resistance of a cable:
Question: What is the resistance of a 1.5-meter-long, 16 mm 2 cable? Given: ρ copper = 1.7 x 10-8 Ω/m l = 1.5 m A = 16 mm2 = 16 x 10-6 m 2 Answer: R = ρ x 𝑙𝑙 / 𝐴𝐴 R = 1.7 x 10 -8 x 1.5/(16 x 10 -6 ) R= 1.7 x 10 -2 x 1.5/16 R = 0.16 x 10 -2 = 1.6 x 10 -3 R = 1.6 m Ω
The effect of cable length: Let’s take above example and now calculate for a 5m long cable. The result will be that the resistance is 5.3 mΩ. If you make the cable longer the resistance increases. The effect of cable thickness: Let’s take the original example and now calculate for a 2.5m 2 cable. The result will be that the resistance is 10.2 mΩ. If you make the cable thinner the resistance increases. Conclusion: Both cable thickness and cable length have a big impact on cable resistance. Please read next chapter what the effect of a high cable resistance is.
2.4 Current, cable resistance and voltage drop
To be able to select the right cable thickness and you will need to know how to much current runs through that cable. The current that flows through a system varies depending on the system voltage. The higher the voltage the lower the current is. Below is an overview of the amount of current that run in 3 systems where to load is the same, but the battery voltage varies:
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