Fuses for 12V DC systems

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  • TullioK
    Junior Member
    • Oct 2011
    • 19

    #1

    Fuses for 12V DC systems

    I'm just about finished with my very first solar system. It's all 12V DC and will be running up to 10 amps in parts. I want to put some appropriate fuses in: 5A on the PV panel (it puts out 4A in full sun), 15A on the battery and 10A on the pump. The only problem is I don't know what fuses to use. I know that this probably seems like a completely stupid question but I can only find fuses suitable for mains voltage and AC. I tested some mains 5A fuse wire and it failed at about 8.5A 12V DC but started glowing at about 7A without actually failing. The mains fuse wire could work then knowing the current it fails at but could someone point me in the right direction for dedicated 12V DC fuses

    I have come accross automotive fuses which seem to be the only 12V option, are these what many of you use with your solar systems?

    Thank you
  • Mike90250
    Moderator
    • May 2009
    • 16020

    #2
    If you are just using 1 or 2 batteries, standard auto fuses are fine.

    What fuses are for? To protect the wiring. Nearly all electronics will blow before a fuse will.
    fuse size is set by the wire size. You can always install a smaller fuse, which will still protect the wire, but never go to a larger fuse, or you risk melting the insulation off the wire.

    Here's a link to a table used in the boating world
    Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister

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    • TullioK
      Junior Member
      • Oct 2011
      • 19

      #3
      Thanks Mike, I've also got a very low current circuit operating some relays but can't find auto fuses below 3A, would a glass tube fuse rated at 100ma for 230V AC be a vialbe option for this?

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