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HPWC Fuse Blown

Discussion in 'Model S: Battery & Charging' started by scaesare, Sep 13, 2017.

  1. scaesare

    scaesare Well-Known Member

    Mar 14, 2013
    I have an early HPWC... I received it in about April of 2013, just before I got my car. It had the original "small" fuses that had issues when operating at 80A. Tesla offered (physically) larger replacement fuses at the time, but I never did obtain a set, and as I was operating on a 50A circuit didn't really pursue it.

    On Monday morning, I came out to a dead HPWC. My breaker in the panel was fine, and a reset didn't help. Opened up the HPWC, and as I had suspected, one of the 2 fuses was blown.

    Given the car is only drawing half of what they are rated for, and the 50A fuses in the car charger didn't go, I don't believe it was an overcurrent failure. All indications are that the torque on the fasteners was still good, as the marks were still correct. No significant discoloration of the fuse contact tabs or mounting terminals. My feed wiring is tight in the lugs and no discoloration there. Given the low current draw, I don't think high heat was a problem.

    I think the fuse just died with cycle life. I had a fuse in one of my car's chargers also die a number of months back (although I've not put that charger back in to service to check, several folks have similarly had them go, only to replace them and have the charger continue fine).

    It so happens that Telsa shipped me an entirely new HPWC about a year in to ownership when I had some charging issues (which subsequently to have been related to a dirty pilot signal pin). So I'm going to swap HPWC's completely, rather than just replace the fuse and put this one back in to service. (Hoping to relocate it anyway, and the charge connector on the old HPWC got run over, damaging the port button)

    So... just sharing a bit in case anybody else had similar issues.
    • Informative x 2
  2. scaesare

    scaesare Well-Known Member

    Mar 14, 2013
    Just to follow up with this, and in case anybody else decides to do similarly....

    Seeing as how I had a brand-new 3-yr old HPWC sitting in a box, I opened it up to compare the design of new vs, old. The only real difference was the fuses and associated buss bars connecting them. Given that I already had my existing HPWC mounted in my garage, wired in to my circuit, etc... I just decided to swap the new fuses in to my existing HPWC. I also swapped out the cable.

    A few notes for anybody who wants to do the same and stumbles across this post in the future:

    • 8,10 and 13mm wrenches are needed to get the nuts and fuses in and out of the different designs
    • Taking a picture of the buss bar arrangement helps, as the orientation of fuses in old vs. new is different.
    • The fasteners are torqued down pretty tight. Make sure to do the same upon reassembly, aas you don't want loose high-current connections
    • The cable assembly lugs are tight as well, careful as you can deform them with a screwdriver
    • The cable conductor ends have a collar over them to prevent the stranded wire from fraying when trying to insert them in to the lug hole. This will deform when you tighten the lugs, making them difficult to remove... a pair of needle nose pliers to tug on the end of the collar helps.
    • The cable has a strain relief clamp inside the housing this is a T-30 torx bolt
    • The ground cable lug is a combo box-drive/slotted head. I used a bug screwdriver, but be careful, there's not much grip there and that sucker was tight
    • The cable also has a crimped metal collar on it that looks like it won't pas through the hole in the housing, however if you push the cable grommet out of the housing with a flat blade screwdriver (carefully working from all sides), it will just clear.
    • The routing of the positive and negative conductors in to the lugs is tight and at an awkward angle. Keep the strain relief clamp loose, and back the entire cable out a bit, and then push it back in slowly as you seat both conductors.
    • Loop the cable ground wire "inward/under" so it doesn't interfere with the cover
    • The protective film on the face of the HPWC cover doesn't peel off easily AT ALL after baking in a hot garage elevated storage shelf for 3 summers...

    All in all it took me about 45 minutes to swap everything out. Works good as new.

    After a few overnight charge sessions I'm going to open it back up and re-check my fasteners to make sure they are still tight.

    Good as new!
    • Helpful x 1
    • Like x 1

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