My last electrical question was too easy - bike electric tricky one!

[Gingernutz]

This explains it well - and explains why you might have several fuses

When connecting a device to your bike you want to make sure that the fuse is located as close to the power source as possible. This is because you are decreasing the odds that a short will happen between the power source and the fuse. If your wiring shorts to ground (the frame, etc.) between the power source and the fuse, then the fuse won't do any good. By only having a small amount of wire between the connection on the power source and the fuse you decrease the odds that it will short out along that length of wire.
A short is more likely to occur after the fuse -- where most of the wires, and devices, are located

So if you have one right at the battery why have another??