Should I connect the lift retrofit kit directly to the battery or to the ignition supply?
Running the power line straight from the battery, with the fuse close to the battery terminal, is the soundest method; the LFT20 draws 10A on average and the thin wiring in the ignition circuit is not designed to carry that load. If an ignition signal is to be used, that signal is fed to a relay coil and the power still comes from the battery. That way the kit is de-energised when the ignition is off.
A comparison of the two approaches:
- Direct from the battery: The lowest voltage drop and the most reliable operation. The disadvantage is that the line stays live even when the ignition is off. For that reason always place the fuse close to the battery terminal and make sure the switch is somewhere it cannot be pressed by accident.
- Ignition controlled via a relay: The recommended solution. A thin wire from the ignition supply feeds a signal to the relay coil; the relay contact then carries the fused heavy line from the battery to the kit. In this arrangement the voltage drop stays low and the kit is completely de-energised when the vehicle is switched off.
- Straight off the ignition circuit: Not recommended. The existing ignition line is not sized for this extra load; the wire can heat up and the tractor's own fuse can blow.
Whichever method you choose, the negative supply must be connected to a clean bare metal chassis point and the supply cross section must be at least 2.5 mm² for a 10A load.
Full topic: Converting a tractor hydraulic lever to electronic control