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power socket - blowing fuses

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by GuzziGirl, Nov 19, 2009.

  1. I have hard wired cigarette style socket to my battery, included a 20A in line fuse on + wire, connected - wire to battery - terminal. When I've plugged in the charger for my phone and iPod the fuses in the chargers have blown. These are 5A & 3A respectively. What am I doing wrong?

  2. Strange one, maybe drawing too much power? Try a 5 amp fuse on the cigarette lighter socket, you'll want that one to blow first, before your chargers do. I put a power socket on my old CX500 with a 5 amp fuse inline, never had any problems with it, even with a portable air compressor.

    Other than that, I've got no idea, maybe someone else will have a clue...
  3. If your blowing 20amp fuses, a 5amp will definatly blow as well [ sorry MV :p ]
    Sounds like a dead short, have you got a multimeter you can use to see whats happening across the socket contacts ?

    If not, visually check the wiring all the way from the battery to the socket and then the earth wire back to the frame or wherever you mounted it, checking for anything that may be causing the short. It could even be a faulty socket and nothing to do with your wiring.

    Ps: I'd be changing the rig to something via a relay, so the socket is only powered up when the ignition is on, could save you an accidental flat battery later on. and put a fuse between the relay and + battery [ as close to the battery as possible ] and the + feed from ign power to the relay "on".
  4. Wise words, happy to be corrected! (although it's the fuses in the chargers blowing not the one for the power socket?)
  5. Ah yep you are right .... the charger fuses are blowing ](*,)
    I have to remember to wake up before posting tech stuff :-# :-w

    In that case Id definatly be looking at the socket itself and how the contacts are sitting at the very least .

    If your unsure of how to fit a relay .... its sounds a lot harder than it is.
    This should help.

    Attached Files:

  6. Thanks for that. I will recheck the wiring. If I understand correctly - the amount of current drawn through the wiring is determined by the device plugged in to the socket. But if there's a short then current is free flowing through the wiring at too high a level and thus blowing the fuses... ?? Does it matter that I've connected the negative wire to the battery rather than to the chassis somewhere?
  7. Look for the obvious,
    1. Confirm that you have you wired the lighter socket to positive to centre pole
    2. Look into the socket in case the centre pole is protruding incorrectly (and touching earth when plug inserted)
    3. Only use a fuse of lower rating than whatever is going to be plugged into it (As per VTRBob's post)
    4. Take note of VTRBob's post he appears to be right on the money.(esp possible faulty socket)
  8. I've re-written this several times now while I re-read the info provided. If I understand correctly, the charger fuse is blowing, not the inline fuse to the socket.

    If so I'm inclined to think its an internal problem with the charger, not the socket setup. If the charger fuse blows, the short / problem is past the charger fuse itself - the charger's internal circuity and/or load. If the socket setup was the problem and the short was within the socket itself (or when something was physically inserted into it), the 20A fuse should blow.

    GuzziGirl, could you run a small test? Use the by halves method I was taught in uni;

    You have 3 items as I understand;
    -- Socket connected to the battery with an inline 20A fuse.
    -- Charger with internal 3A/5A fuse.
    -- Phone / iPod that connects to charger.

    Bike Battery -> Socket (20A inline fuse) -> Charger (3/5A internal fuse) -> phone/iPod


    If so test as follows;

    Take the charger and ensure a new fuse inside it. Plug it into the car with no phone/iPod connected. If it blows the fuse, charger stuffed / internal short. If it passes, ok so far.

    Now plug the phone/iPod in, if it blows the fuse, its either stuffed or maybe running the wrong fuse. I doubt, but could be the initial inrush current of the charger when the load (phone/iPod) is connected. Try buying a slow blow fuse of the same rating (3 or 5 amps) like this one (assuming glass tube type).
    If it works now test it with the bike.

    At this point you should have determined if the charger is stuffed or not, if it lives all of the above tests, the problem lies with with the socket or the socket and charger working together.

    Now test the socket. First inspect all wiring and check for shorts. If you can obtain another charging device (for example, Nokia car charger) and test with no phone attached on the bike socket. If it holds up, connect a load (in this example, a nokia phone). If it holds up, move on.
    Another way to test the socket if you can get access to a multimeter is the following:

    Disconnect the Socket from the battery and check two things; what should be connected and what shouldn't be also. I.e. Check the positive battery terminal does connect to the center pin of the socket. Then, check that the positive battery terminal doesn't connect to the negative terminal of the socket. Same for the negative, check the negative battery terminal does connect to the negative terminal on the socket, then also check the negative battery terminal doesn't connect to the positive terminal of the socket. Does this logic make sense with checking? You want to check what is meant to be connected, as well as what shouldn't be connected.

    Assuming we have got this far and everything is ok, there is a problem with the charger and socket together. However I suspect if the internal fuse of the charger is blowing and not the inline 20A socket fuse, I doubt we'll get this far, but lets see anyway.

    Actually, I don't know what to write, if the charger's internal fuse is blowing, I'm 99% sure it isn't the socket at all. Try the above and let us know how you go.

    Nope. Better off on the battery I say, more reliable.
  9. What sort of chargers as described here have internal fuses? None of mine have.

    In any case, Browny's suggestions are on the money. By plugging the suspect charger into a car cig. socket it will confirm or eliminate the bike one as being faulty.
  10. You've wired the socket reverse polarity ](*,)

    The chargeers have reverse polarity protection ( a diode across the + and -) AFTER their fuse, it blows the fuse instantly when reverse polarity is applied.

    + goes to centre of ciggie lighter, - goes to the outside
  11. Thank you to everyone who has replied. I have found the problem. The socket was a pre-wired, sealed unit with 2 black wires - one of which has a white stripe - and I was wrongly informed (by the guy in the bike shop) that the one with the stripe was the negative. I now know this was wrong and I had the neg wire connected to the + on the battery. Luckily the devices I tried out are all still working properly. All my chargers have internal fuses, 2 are easily accessible by unscrewing the ends. One was a sealed unit that had to be pried open and the very helpful guy at the electronics shop soldered a new fuse in for me. In the end, no harm done and I've learned heaps. Thanks again for all your replies and suggestions. :)
  12. Good to hear, GG. All too often people rock up here (and other forums), and post their tales of woe, looking for help. Then later on, when heaps try to help out the OP never returns to let people know how it went (or to contribute in other ways).
  13. all points to Ducfreak, good catch dude, I didn't think of that at all.

    +1 mjt57 about the reply of success.
  14. :) glad its all sorted.
    Grey hair and E.E. after name (Electronics Engineer) makes it easy
  15. Makes two of us except I don't have the experience of grey hair... :grin:
  16. Beat me to it.

    I agree with the guy at the bike shop, I'd have wired it up that way BUT then again I also tend to buzz things out to double check before plugging anything in.

    I haven't gone grey yet (a couple have appeared) but I've got a certificate stating I qualified as a Telecommunications Technician back in 1986.