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Idiot-Proof Jumper Cables ??? — Parallax Forums

Idiot-Proof Jumper Cables ???

ercoerco Posts: 20,260
edited 2010-07-29 03:50 in General Discussion
Technology for people who can't be bothered with getting the polarity right when using jumper cables in a car.

http://www.woot.com/

Should these people even be driving?

Michelin_Smart_Jumper_Cables_with_Automatic_Polarity_Adjustmentux9Standard.jpg

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·"If you build it, they will come."

Comments

  • sylvie369sylvie369 Posts: 1,622
    edited 2010-07-22 15:53
    erco said...
    Technology for people who can't be bothered with getting the polarity right when using jumper cables in a car.

    http://www.woot.com/

    Should these people even be driving?
    I think they have to drive to get to their jobs at Microsoft.

    http://techlogg.com/2010/07/microsoft-instaload-does-away-with-battery-polarity/1058
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2010-07-22 16:02
    'Might as well make this interesting. Kudos to the first person to post a working schematic for the circuitry in the pod. I know how to do it with two DPDT relays and a couple diodes, assuming the "dead" battery isn't too dead. But the pod is too small for relays capable of handling high starting currents. I'd have to think about how to do it with MOSFETs, which is almost sure to be what's in the pod, along with some additional circuitry. Remember, it has to work regardless of which end is connected to the dead battery and in which order the ends are connected. Let's assume the dead battery can be as low as two volts to maximize the challenge. (My relay circuit would not work in that case.)

    -Phill
  • davejamesdavejames Posts: 4,047
    edited 2010-07-22 16:28
    ...errrr - the instructions state that correct polarity must be observed when connecting to the dead battery. It's the polarity connection to the source battery that, quote, doesn't matter, unquote.

    So, if I know enough to make sure the polarity is correct for the dead battery, what's the big deal in making sure the polarity is correct for the source battery?

    This is nothing more than a product looking for a market rather than the market looking for a product.

    DJ

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  • Peter KG6LSEPeter KG6LSE Posts: 1,383
    edited 2010-07-22 17:14
    If it is FET based . it must be a nice sized FET 100A +..

    I am kinda curuios to see the insides now .

    EDIT I Know how thease work now . LOLs its just a a diode .or 2 .

    Peter KG6LSE

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    "Carpe Ducktum" "seize the tape!!"
    peterthethinker.com/tesla/Venom/Venom.html
    Never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway. —Tanenbaum, Andrew S.
    LOL
  • HollyMinkowskiHollyMinkowski Posts: 1,398
    edited 2010-07-22 17:16
    Well, if the instructions say that the source battery polarity of connection
    does not matter but the other does then wouldn't a simple bridge rectifier
    work?


    I say it's not idiot proof unless polarity is unimportant at both ends.

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  • Peter KG6LSEPeter KG6LSE Posts: 1,383
    edited 2010-07-22 17:25
    why we just dont use anderson Power poles on the bumper or the like for all cars is beyond me .. there RP proof and safer as they dont put a arc or spark anywhere near the Batt .

    Peter KG6LSE

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    "Carpe Ducktum" "seize the tape!!"
    peterthethinker.com/tesla/Venom/Venom.html
    Never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway. —Tanenbaum, Andrew S.
    LOL
  • edited 2010-07-22 17:35
    Twelve dollars looks like a good price but I think it is for small cars.· Some of these stores charge a premium for copper jumper cables but Harbor Freight has a good price.

    It is hot here and I had to jump a van with another van two days ago about six times·and the cables got hot.

    It isn't really that hard: When you connect the cables to the battery it is: Black on Black and Red on Red.· If you see sparks jumping then you did it wrong.· And you don't touch the cables together.· Ouch.

    I'd be more worried if the circuitry couldn't handle over 300 cranking amps.· We have a battery backup with 450 cranking amps and it won't start a van.· Van batteries take at least ten minutes to jump from a dead battery and if you leave the lights on too many times, the battery won't hold a charge.
  • W9GFOW9GFO Posts: 4,010
    edited 2010-07-22 18:57
    8 gage aluminum wires, that's about the equivalent of 10 gage copper and they apparently won't work at all if the "dead" battery is less than 8 volts. And to top it off, they aren't truly idiot proof since you still have to get the polarity correct on the "dead" battery. Although I would guess that if you get the polarity wrong it won't short so that is probably it's only redeeming feature.

    They're better than nothing, but not by much.

    Rich H

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    The Simple Servo Tester, a kit from Gadget Gangster.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2010-07-22 19:38
    So my challenge still stands. How would you make it totally idiot-proof, given the criteria I laid out?

    -Phil
  • Erik FriesenErik Friesen Posts: 1,071
    edited 2010-07-22 20:04
    All it takes to make a genius of checking polarity is hooking it up backwards once.(hopefully) I did it when I was about 17 on an older ford. I think all it did was took out the voltage regulator. Another thing to watch for is lots of sparks. If it seems a little like welding, you better check your polarity. I have been saved by that fact one other time because the clamps would not make good contact.(thankfully)

    If the battery is sitting at 0 volts, which seems likely if the dome light has been on all night, how are these supposed to figure that out?

    Gimmic alert!
  • TinkersALotTinkersALot Posts: 535
    edited 2010-07-22 20:17
    now waiting for a new and improved version of an idiot that will manage to screw up this "idiot-proof" design
    hehehehe
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2010-07-23 15:59
    I suspect that Holly has got it right - a bridge rectifier. I keep thinking about installing one on my projects every time I fry something with reversed polarity. They already come in huge amp ratings.

    But it does demonstrate how technology is making some of us rather mindless. Not only does it seem that don't you have to comprehend polarity, but you can get color coordinated as well.

    Wouldn't it be a lot better if all cars merely provided a polarized socket that resolves the problem by using a mating polarized plug on a standarized jumper cable? What we are using now is so Neanderthal.

    They are made for a husband and wife team - the competent spouse handles the important end. I refuse to be gender specific.

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    Ain't gadetry a wonderful thing?

    aka G. Herzog [noparse][[/noparse] 黃鶴 ] in Taiwan

    Post Edited (Loopy Byteloose) : 7/23/2010 4:09:35 PM GMT
  • ElectricAyeElectricAye Posts: 4,561
    edited 2010-07-23 16:23
    There's no such thing as idiot rpoof.
  • HollyMinkowskiHollyMinkowski Posts: 1,398
    edited 2010-07-23 16:32
    Just had a thought while reading the new replies to this thread.

    I think you could make a set of cables for this using 2 diodes,
    two LEDs and two 1/4watt resistors.

    It would not automatically correct for polarity but it would keep
    power from flowing if it was hooked up wrong at either end.
    The LEDs would light up green to indicate polarity is correct.

    Is this right? Would it be this simple....

    If this would work, and be this cheap to make, then someone should
    start selling them wink.gif
    Direct TV marketing, like that silly shamwow guy.
    (include a cheap pair of plastic safety goggles in the box)

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    justasm.blogspot.com/

    Post Edited (HollyMinkowski) : 7/23/2010 4:40:18 PM GMT
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2010-07-23 16:38
    Well, these cables certainly should have a green and a red LED for indicators on the important end OR go in the trash can.

    Yes, you could block the power if the logic was wrong with just two diodes. But there are really a few combinations that might do odd things to the LEDs due to backflow.

    BTW, the best jumper cables are made from arc welding wire cables - huge diameter and all copper. You can make them extra long and not suffer voltage drop. Just add your own clamps to the ends. Soldering takes a propane torch.

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    Ain't gadetry a wonderful thing?

    aka G. Herzog [noparse][[/noparse] 黃鶴 ] in Taiwan
  • davejamesdavejames Posts: 4,047
    edited 2010-07-23 17:26
    @ Mr. Pilgrim,

    The source battery would connect to a full wave bridge rectifier AC inputs making that end of the cable polarity independent.

    The output of the bridge rectifier would provide the +/- rails to an H-bridge (hefty MOSFETS).

    The output of the H-bridge would connect to the "dead" battery.

    The "direction" of the H-bridge would be contolled by the cable (connected to the "dead" battery)·that had the most positive voltage. This could be determined using a diode-OR approach or by using a battery powered voltage comparator to detect the "dead" battery's remnant positive voltage.

    If the suspect battery was truly dead - no potential difference between its terminals, then this method would not work.


    Yea/Nea?

    DJ

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    Post Edited (davejames) : 7/23/2010 5:33:39 PM GMT
  • HollyMinkowskiHollyMinkowski Posts: 1,398
    edited 2010-07-23 17:39
    Yes, if the target battery is totally dead then it really complicates things.

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    justasm.blogspot.com/
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2010-07-23 18:19
    DJ,

    I think your idea would work. Nicely conceived! I think you would need a bridge rectifier from the "dead" battery, though, to power the logic necessary to switch the pMOSFET transistors in the H-bridge.

    -Phil
  • davejamesdavejames Posts: 4,047
    edited 2010-07-23 18:25
    Mr. Pilgrim,

    (thank you very much!)

    Attempting to take the "dead" battery's voltage into consideration was the basis for suggesting a separate battery powered circut to control the H-bridge.

    So - when do we go into production?


    (smiles)

    DJ

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  • Chris_DChris_D Posts: 305
    edited 2010-07-23 18:44
    Just remember the golden rule...

    The world can always provide better idiots ;-)

    Chris
  • HollyMinkowskiHollyMinkowski Posts: 1,398
    edited 2010-07-23 22:09
    Chris_D

    LoL!

    I once coded a library to be idiot proof...lots of comments,
    lots of documentation and the whole thing exhaustively tested.

    Then they hired just the idiot that could make a mess with it smile.gif


    On further reflection I think the best way to make a semi-idiot-proof
    jumper cable is with 2 LEDs, 2 resistors, 2 diodes and a switch. At
    least this is perhaps the best way at a reasonable price.
    (it still is problematic if the target battery is totally dead)

    Wire up using the parts in the obvious way so that at both ends
    current cannot flow if the polarity is wrong, and have the green LED
    light up when the polarity is correct. Do this at both ends and when
    both LEDs are on press the switch that is in the middle of the cable
    to connect the 2 batteries. smile.gif

    EDIT:
    If I were designing a jumper system for new cars I would place a
    cable and a socket in the trunk connected to the battery by heavy cable.
    This way you don't need to expose yourself to the possible disaster that
    acid and hydrogen can be near the battery itself. I'd make the cable socket
    polarized and place a breaker switch nearby in case someone shorted
    together the clips on the cable end. You could use a bridge to ensure that
    when connected to another car's battery the polarity would always be correct.

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    justasm.blogspot.com/

    Post Edited (HollyMinkowski) : 7/23/2010 10:18:26 PM GMT
  • kwinnkwinn Posts: 8,697
    edited 2010-07-24 03:19
    Sorry folks, but I know from experience there is no such thing as "idiot proof". Idiots are just too creative.
  • MoskogMoskog Posts: 554
    edited 2010-07-24 08:19
    HollyMinkowski
    Another problem today, especially with modern cars, you can face high voltage peaks when connecting the batteries (when you see the sparks, I guess) -that can possible kill high sensitive electronic devices, like microcontrollers, in your car. Maybe you should figure out something to eliminate that problem too.

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    KjellO
  • HollyMinkowskiHollyMinkowski Posts: 1,398
    edited 2010-07-24 08:56
    Moskog

    Good point!
    I had not even thought of that but it could be a problem.
    Maybe an expensive problem, they charge a fortune to fix
    the computers in a car...I know from unhappy experience :'(

    My electronics knowledge is so limited that i really have no clue
    how to protect the car's sensitive components from sparks.

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    justasm.blogspot.com/
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2010-07-24 09:26
    I suspect that it is a genuine case of KISS - Keep It Simple Stupid.
    Nothing will ever replace using generic jumper cables and learning to properly wire them in parallel. After all, one does have to make at least one observation about polarity to use these rather absurd devices.

    I suspect Holly could make something with LEDs and merely ONE diode, but it still wouldn't be as good (more fragile).

    My mom - bless her soul - could make any technology crumble with merely one touch. If it was a dial, she would push and pull rather than turn. If it were a push button, she would turn. At least she was a great cook, even if the toaster was always going up in flames. I guess that is why I learned to observe technical things so minutely.

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    Ain't gadetry a wonderful thing?

    aka G. Herzog [noparse][[/noparse] 黃鶴 ] in Taiwan
  • HollyMinkowskiHollyMinkowski Posts: 1,398
    edited 2010-07-24 09:49
    Loopy

    I am a bit like your Mom when it comes to mechanical things. Electronic things
    I generally understand, but I must have bad karma for mechanical stuff because
    every time I ever tried to use a wrench a service guy would have to be called
    or something would end up having to be thrown away ...LoL

    I have tried several times to come to grips with hardware, I even bought a hobby
    lathe, I never used it, which is probably a good thing. I'd probably be missing
    a hand or foot by now if I had ever plugged it in.

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    justasm.blogspot.com/
  • GadgetmanGadgetman Posts: 2,436
    edited 2010-07-27 12:37
    That 'jumper cable' looks to thin to be used to start a car.
    (My father's charger can give a 300A boost for jumpstarting a car, or tractor... It has 'rather thick' cables)

    And if all you want to do is recharge the battery a bit, you could use a cable with 'cigarette lighter' connectors instead.
    (May need some sort of limiter to keep it below 10 or 16A, though)

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  • edited 2010-07-27 19:51
    Holly,

    The salesman at Honda told me I can't change the headlamp in the new 2010 cars because it (the fixture) is too tight and I would probably break something. They do this so that they make money. Some of these cars like Hyundai have to have a service plan because you have to take almost everything out of the engine space just to fix something. I would have to take the battery out or slide it over just to change the halogen headlamps which could take me twenty minutes because I would have to go through my tools and find the right wrench.

    I've broken bolts which is common when you change the tires in cars. You just have to have some spares on hand because you will have to hammer them out after they break. It is meant to happen it seems.

    I've bought parts at Pepboys for my car and the parts wouldn't fit because my car was between years. I've had my reflector fall off because the grommets went bad and they want something like $60 for a lense which is cheap compared to $300 for some of these newer cars.

    I've had some computer problems with hardware and after having hardware guys just take my money, I've learned to fix some things on my own while leaving other things alone.

    I think it is more willingness to spend the time to learn how to fix or build things. It is more about having the right tools and sometimes you have to use a little finesse. My neighbor is a retired mechanic and learning from someone skilled means all the difference as he told me what was wrong with my car after it wouldn't start. I just went out to Pepboys, bought the part and installed it. It saved me taking the car into the dealer and it is more honest because I've had some of them try to take advantage of me.

    Chuck
  • mctriviamctrivia Posts: 3,772
    edited 2010-07-29 03:50
    why has no one pointed out that the dead car battery could not possibly be at 0V. If the battery is that dead it is broken. True traditional jumper cables can jump a car that has no battery and it can keep running off the alternator until you shut it off or run out of fuel but there just is no possible way for a micro or any other circuit to handle a car with no battery. Under normal conditions a battery that is still worth recharging will never have a voltage lower then 30% of running voltage.

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