Tech corner

  1. Phenomenon: Half-Blown Fuses

    Phenomenon: Half-Blown Fuses

    A question that we get not-infrequently, when we mention to customers that they need to visually inspect their fuses rather than just continuity-testing them to make sure they're not "half-blown" (i.e. degraded) is:

    "Is it really possible for a fuse to half-blow? I've never heard of that!"

    The answer, though it may surprise many, is a resounding YES. The attached photo is of a 3.15A fuse from a Cerbo GX power supply wire, and it has "half-blown", and what we mean by that is: under 0A load, the fuse will pass full vbatt (13.6v in this case), with no voltage drop (at least, none within a hundredth of a volt).

    As soon as even the smallest load (~5ma) is applied, however, voltage through the visibly melted fuse filament drops to roughly half vbatt, and the voltage drop gets worse as the load is increased. At ~2.5A, voltage through the filament has dropped to ~1.6v.

    The lesson here is simply to understand that a cursory visual inspection of a glass fuse such as

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  2. Victron Training Days

    Come see us at the Victron Training days - 11/30 & 12/1 for professionals, and 12/2 at our shop for DIY-ers. More info is at

    Victron Training Days


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