Should I remove the kit when welding or connecting a jump battery?
If you are going to do electric arc welding on the tractor, first disconnect both battery terminals and clamp the welding earth right next to the part being welded; welding current passing through the electronic board leaves permanent damage. With a jump battery there is no need to remove the kit, as long as the 12V negative chassis arrangement is preserved and the polarity is not reversed.
The two scenarios differ from each other.
- Arc welding: Welding current flows along the lowest resistance path between the earth clamp and the weld point. If the clamp is attached far away, that path can pass through wiring harnesses and electronic boards. So disconnect the positive and negative battery terminals and clamp the earth a few centimetres from the part being welded; if possible, disconnect the kit's supply terminals as well.
- Jump battery: As long as the system is 12V negative chassis, taking a jump start does not require removing the kit. The critical point is polarity: positive to positive, negative to chassis. Reverse connection and jump starting from a 24V source destroy the electronics instantly.
Another risk is load dump: disconnecting the battery cable while the engine is running creates a high voltage surge because the energy produced by the alternator has nowhere to go. So never disconnect the battery clamp while the engine is running; do cable work with the engine stopped.
The LFT54's embedded control board has current and position sensor protection, while the LFT20 has no board, processor or sensor; consider the LFT20 more vulnerable to this kind of mistake.
The full topic: Converting a tractor hydraulic lever to electronic control