For a more general rule on fuses, it's not just the source of power you're protecting, it's preventing the destruction of everything downstream to the fault and causing a fire from burning off the insulation.

In my previous job we considered about 4-5 A per sq mm of copper cable as the sensible limit, but these were very high reliability, continuous use items with a 20-30 yr service life. You could double that comfortably for short bursts. It does get a bit crazy above about 500A due to the volume vs surface area problem but I don't think many featherweights are pushing anything like that for more than a couple of seconds.

So if you wanted to protect some 10 sq mm cable you'd aim for a fuse rating between 60A and 100A, depending on how fast a blow fuse it is, and how hot it gets in your robot. Obviously still protect the battery, but you should aim to protect the lowest rated item.

Take a look at some tables like these below to see what I mean about current capacity:
https://www.cse-distributors.co.uk/c...fo/table-4e1a/

Note that although those are conservative figures for continuous use, they're also assuming a pretty big temperature rise (60deg C), I would imagine you could easily be 60deg C inside a hard working robot. Your mileage may vary.