odd cable

Discussion in 'General Electronics Chat' started by electronis whiz, Apr 10, 2014.

  1. electronis whiz

    Thread Starter Well-Known Member

    Jul 29, 2010
    519
    27
    I know this is kind of car related, but I think an ok topic. I was at thrift store the other day, I saw a pretty heavy power cord for a car. Has 2 identical ends though. Both the type that would fit in a socket. I thought this like a jumper cable of some sort, or what.

    I figured nothing else it's heavy enough I could cut in 2 and use as a cord to make an inverter out of an old UPS unit some time.

    I have seen things advertised to jump cars through lighters, but I'm not sure how that would even work. I would think even just charging battery without trying start would pop a fuse or something. I'm just curious if anybody ever used a cable like that, or knows if they would actually safely do what they claim.
     
  2. Little Ghostman

    Member

    Jan 1, 2014
    294
    97
    I didnt think the wiring behind those lighter things was that heavy, I wouldnt think pulling starting current through it would be a good idea, I would worry about starting a fire or damaging the insulation in the loom.
    Why do they make so many things for those little sockets? Why not just pop the bonnet(Hood) and jump in the NORMAL way?? I dont see any advantage with these cables. I would just use the cable for something else
     
  3. richard.cs

    Member

    Mar 3, 2012
    162
    31
    The advantage of those cables is that they allow idiots who can't be trusted not to connect jumpleads backwards and kill themselves to start their cars after leaving the lights on. The cables usually have enough resistance to limit the charging current to 10A or so (either because they're really thin or with an actual resistor) so fuses don't pop.

    It works so long as the starting battery in the dead car is in good condition, just flat. You throw a few Ah in over 20 mins or so and then all that energy can be delivered over a couple of seconds to start the car (hopefully).
     
  4. jrz126

    New Member

    Sep 17, 2008
    7
    0
    I received one as a Christmas gift 10 years ago, never used it, but i did take it apart.
    It has some simple circuitry to it. Likely a boost converter and current limiting protection.
     
  5. wayneh

    Expert

    Sep 9, 2010
    12,090
    3,027
    Exactly, and there is no risk of sparking a hydrogen explosion either.

    You cannot get anywhere near enough current through the cable to start a car anyway, maybe just enough to blow the accessory fuse. You have to have REALLY good cables to actually start a car through them. It's much more about charging the dead battery than delivering starting current.
     
  6. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,507
    2,367
    Anyone who thinks he can jump start a car through the Auxilliary/lighter socket is dreaming, may a slow charge.
    The Jumper cables I made up from 100amp welding cables some years ago, afford virtually no volt drop, and I have measured the current in the past and it runs around 100amps plus.
    Max.
     
  7. DerStrom8

    Well-Known Member

    Feb 20, 2011
    2,428
    1,328
    These cables are not designed to jump-start a car--that's a good way to blow a fuse. They are designed to be used as a trickle-charge just to give your flat battery enough juice to get the car started, then the alternator will help recharge it some.

    I had one when I had my old BMW, used it frequently. I finally broke down (before the car did) an bought a new battery.
     
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