Which fuse should I use for the LFT20?
The LFT20 runs on 12V DC and draws 10A on average. The general rule for a fuse is about 125% of the load; that gives a calculated value of 12.5A, and rounded to standard values a 15A fuse is used in practice. The fuse must be placed on the positive supply line, as close as possible to the battery positive terminal, so that the whole length of wire is protected against a short circuit.
Points to watch when selecting and placing the fuse:
- Position: The purpose of the protection is to protect the wire, not the device. That is why the fuse must sit right next to the source, that is, at the point closest to the battery terminal.
- Type: An automotive blade fuse holder is sufficient; it must be fixed so that it does not take in water and does not come open with vibration.
- Rating: 15A. Fitting a higher rating leaves the wire unprotected; a lower rating causes needless blowing at start-up.
- Wire match: The fuse rating must stay below the current carrying capacity of the wire. A 2.5 mm² cross section is suitable for a 15A fuse.
If the fuse keeps blowing, do not increase the rating. First check whether the cable is jammed, whether the wires are chafing on the chassis and whether the motor turns freely. Since the LFT20 has no board and no sensor, a mechanical jam shows up directly as current.
Full topic: Converting a tractor hydraulic lever to electronic control