I have a 6V circuit that draws around 4.2A. The 6V power supply is a Lead Acid Battery. So for safety reasons I want to protect the circuit with an external fuse block. Can I use a 12V 5A fuse? Or is it the total power of the circuit that matters(here in this case around 26 watts)? If that is the case then I'll need a 12V 3A fuse I guess?