I have a 12V DC car socket is connected to a car battery and cable with 12V car plugs on each end. The socket and each of the plugs has its own fuse, which seems unnecessary. If I were to blow a fuse, I wouldn't want to check 3 places.

I'd like to keep the socket's fuse since it's directly connected to the battery and remove both fuses from the male-male cable. However, since a fuse is part of the spring-loaded mechanical structure for a 12V car plug, I can't just replace it with a wire. Is there any kind of placeholder that I can use? Will I need to disassemble a glass fuse and wire the ends together? Is this all a terrible idea?

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    \$\begingroup\$ Simplest would be to replace them with fuses rated several times higher than the one you want to keep. \$\endgroup\$ – user_1818839 Nov 18 '20 at 23:40
  • \$\begingroup\$ Oh, duh. Yes, that would be a lot simpler. =) \$\endgroup\$ – jamesdlin Nov 18 '20 at 23:44

Fuses in car protect car wiring from overheating and fire. Plug fuses protect connected device. Remove them or shorten bad idea.

  • \$\begingroup\$ If the connected device relies on power from the connected battery, why would I need 3 fuses in series? Why would a fuse in the plug provide more protection for the connected device than a fuse in the socket? Do I really need a fuse in each end of the male-male cable? \$\endgroup\$ – jamesdlin Nov 19 '20 at 5:34
  • \$\begingroup\$ @jamesdlin Some devices may have electronic protection. I. e. 12v to usb converters. Use as it was designed. Modification may decrease reliability. Most expensive repairs may be if car wires damaged. Automotive socket may hold not more than 5 Amps. And it is not a few fuses connected in series. It is different levels of protection. For example one fuse can protect few socket and radio. \$\endgroup\$ – user263983 Nov 19 '20 at 13:07
  • \$\begingroup\$ I still don't understand why the fuses in a 12V male-male cable would make any difference. Shouldn't a device that wants or needs electronic protection have its own fuse, then? Why would it expect anything from a gender-changing extension cable? Why would it expect such a cable to be present at all? Also, FWIW, the socket (with the fuse I want to keep) in question is connected to a car battery but is not actually in a car. \$\endgroup\$ – jamesdlin Nov 19 '20 at 13:15
  • \$\begingroup\$ Fuse in cable protects cable. You may connect device which consumes more current then cable allowed to conduct \$\endgroup\$ – user263983 Dec 16 '20 at 15:44
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    \$\begingroup\$ That's true, but fuses are also meant to be replaced. I would expect that either the cable would need to specify requirements for those other characteristics or would be tolerant of variance in them. \$\endgroup\$ – jamesdlin Dec 17 '20 at 2:40

All your bought hardware has probably some (EU/US) certification. In that case it needs to provide short circuit/overload protection.

More fuses makes your stuff better protected.

Let's say you remove those from the car plug and your device is less protected and vice-versa when you remove and short the fuses from your wiring, the wiring is more prone to melt when shorted/overloaded.

  • \$\begingroup\$ Assume all of the fuses have the same rating. Why would a fuse in the cable provide more protection than an equivalent fuse at the power source? \$\endgroup\$ – jamesdlin Dec 16 '20 at 23:22

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