When my car battery died, my son came over to give me a jump. The jumper cables looked rather small, maybe 5/16 inch, including insulation. He got them from a website that sells close-outs and features only one item per day. Well, I hooked them up -- no spark. I found that to be a bit odd, so I left them on for a while, but the battery did not charge. I disconnected the cables and measured the voltage at the clips -- 12V. I figured there must be a high-resistance contact somewhere.
Later, after other cables got my car started, I did a post-mortem. I examined one of the wire crimps, and it looked like only a few strands were crimped and the rest must have been cut off by mistake. Not so! After cutting off the alligator clip, I noticed that the cable was almost all plastic, with just a tiny core of copper -- maybe #22 AWG. This is not good enough for lamp cord, but maybe speaker wire. Who makes jumper cables out of such thin wire? Monkeys!
This entry was submitted by Noor Singh Khalsa and edited by Rob Spiegel.
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Reminds me of a 220 volt plug strip I bought over in asia once. Out of curiosity I hacked it open and discovered unisulated wire no larger than 22 or smaller gauge wire bused along the receptacle poles. And people over there use these to run appliances! They would never get a UL rating over here.
Not sure how dangerous 22 AWG wire would be in jumper cables. It would very quickly burn an open into the circuit, and then never conduct again. "No SparK" would imply that the circuit were still conductive when you disconnected the clamp from the battery post. That cable would have long ago ceased to have a complete connection.
Jumper cables are a particular interest to me - Living in Texas, where even a really good battery won't last more than 2-3 years, I have done more than my share of jumping cars (wife's + 2 kids' cars) We also tend towards diesels in my family, so the cable weight is not the only thing that matters. Those stupid little side posts, for some reason placed in close proximity to a substantial piece of steel, give me the heebie-jeebies every time I try to connect the positive cable. It can be difficult to get a good connection capable of supporting more than a few amps.
I have a cool little DC ammeter that I can lay right onto the cable to see how much current is running, if I have a decent connection.
I have 4-5 sets of pretty decent cables that I bought at a club that rhymes with "Pam's"
My jumper cables are long, very heavy, and a bit awkward and cumbersome to use, but they get the job done every time. One recent evening I was walking through the university parking structure after teaching my class when two damsels in distress inquired whether I had jumper cables. Paraphrasing Paul Hogan's Crocadile Dundee character, I pulled mine out of the boot of my car, saying, "THAT's a jumper cable!" I have always made sure my wife has high-quality jumper cables in her car and knows how to use them safely, and we have done a few jumper cable and flat tire change drills in our driveway.
Spend $70 and get a "Jiffy Jump" or equivalent. Keep it in your trunk and top it off every 3 months or so. I've used mine for about 5-10 years now and it's never let me down (with lot's of jumps under its belt over that time).
It has a load connect switch so you can connect it directly to the dead battery without worrying about a spark blowing your face off (not with the Jiffy Jump, but I've had batteries blow, not pleasant).
I have made a few sets of jumper cables for my own use, and the best wire seems to be a fairly fine stranded cable that I picked up someplace, similar to welding cable but only about 0.300" diameter, with conductors about 0.25 diameter. They work for cranking as well as for charging. And the way to avoid having a problem with cheap clamps is to run the wire up to the tips of the clamps so that the high resistance of the steel, clamp does not matter.
I have seen jumper cables that were made from solid aluminum wire, with polyethlene insulation, which might be adequate for one use. They had been abandoned in a parking lot, probably after one use.
There are several ways to make cheap booster cables:
1. Make up your own wire gauge. Instead of using standard gauge wire diameter, invent your own standard. For example, 4 AWG cable should have at least 0.204" conductor diameter, but you can invent a new standard, and call wire that is 0.040" diameter "4 gauge cable." Beware of cable that it is not marked with a known wire-gauge standard, such as "AWG."
2. Make them very short. Never mind that it will be inconvenient for the user. Booster cables should be at least 15 feet long to be easy to use.
3. Use cheap clamps and don't pay attention to how the cables are attached to the clamps.
4. Use an impractically small cable diameter, because many consumers are ignorant and your profits will be huge until people figure out you are producing useless crap.
5. Don't use copper cable because it is expensive.
A good pair of booster cables should be 15 - 20 feet long, and made of 4 AWG (or larger, not likely larger) stranded copper cable. If the cable diameter is less than this, in most cases, there will be too much voltage drop during (attempted) cranking. Do the math: 0.26 milliohms per foot X 30 feet X 300 A = 2.3 V drop, excluding the clamps and connections. Any more voltage drop than this, and the cranking voltage will drop well below 10 V, which is usually too low for good cranking. With smaller-diameter cable, you can charge a battery, and wait until it is charged before cranking (if the battery will hold a charge). Expect to pay more than $50 for a pair of useful booster cables, and more than $100 for a good pair. If the price is under $50, be very suspicious.
For industrial control applications, or even a simple assembly line, that machine can go almost 24/7 without a break. But what happens when the task is a little more complex? That’s where the “smart” machine would come in. The smart machine is one that has some simple (or complex in some cases) processing capability to be able to adapt to changing conditions. Such machines are suited for a host of applications, including automotive, aerospace, defense, medical, computers and electronics, telecommunications, consumer goods, and so on. This discussion will examine what’s possible with smart machines, and what tradeoffs need to be made to implement such a solution.