What cross section in mm² should the lift retrofit kit's supply wire be?
For the LFT20's 10A average current and roughly 3 m one-way distance, a cross section of at least 2.5 mm² (about 14 AWG) is recommended. On a 12V system the 3% voltage drop limit leaves only 0.36 V of margin, so distance is the decisive factor in the cross-section calculation. If the distance grows or the wire runs at engine-bay temperature, go one size up.
Factors to take into account when choosing the cross section:
- Total length: The calculation is based on the sum of the positive and negative runs. 3 m one way means a 6 m circuit length.
- Temperature: Temperatures of 90-105 °C reached in the engine bay increase the resistance of copper by roughly 27-33%. For wires passing through hot areas it is reasonable to go one size up.
- Connection quality: A loose lug or an oxidised chassis point adds enough resistance to make the cross-section calculation meaningless. Crimp the lugs with the proper tool and clean the paint off the chassis surface.
- Fuse match: The fuse rating must stay below the current carrying capacity of the wire; a 2.5 mm² cross section is compatible with a 15A fuse.
Checking after installation is simple: with the kit running, measure the voltage at the kit's supply terminals and, at the same moment, the voltage at the battery terminal. Since at 12V the 3% voltage drop limit leaves about 0.36 V of margin, the aim is for the difference between them not to exceed that order noticeably; if it does, the cross section or the connections are inadequate. This threshold is an engineering derivation, not a manufacturer statement.
Full topic: Converting a tractor hydraulic lever to electronic control