EEVblog Electronics Community Forum
General => General Technical Chat => Topic started by: fubar.gr on February 12, 2015, 12:58:03 pm
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I bought these jumper cables really cheap.
(http://i59.tinypic.com/xfpz07.jpg)
Nice thick cables, capable of handling 1200A, according to the writing on the package
But on closer inspection:
(http://i62.tinypic.com/2hx20k6.jpg)
The actual copper is less than 10% of the cable thickness!
I measured the resistance of each cable and it was 58mOhms, or 116 mOhms total for both cables. These cables can't handle more than 20 Amps tops.
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Thanks for providing real example of crap/fake jumper cables. Is it possibly to deduce cable quality without destructive testing? Would any of these tests (4 wire mili-ohm reading, weight, flexibility, buoyancy) be good enough to indicate fake cables?
Topic about jumper cables was disccused recently here:https://www.eevblog.com/forum/chat/jump-starting-a-car/ (https://www.eevblog.com/forum/chat/jump-starting-a-car/)
EDIT: just noticed that crimp connection is a POS. Is it even a real copper (looks like aluminium)?
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EDIT: just noticed that crimp connection is a POS. Is it even a real copper (looks like aluminium)?
Could be steel, i had a few chinese cables made of steel.
Greetings,
Peter
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Manufactured at The crazy World of Arthur Brown!
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They'd probably survive 1.2kA for a second or two... what do you estimate is the diameter/area of the conductor?
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I'm not sure they exist outside of the US, so our non US readers might not know what I'm talking about, but the insulation looks like the stuff from which they make Circus Peanuts.
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There is no destruction involved, just pull one of the plastic sleeves that cover the wire crimp and look.
Some time ago I paid 140€ for a 400A 6m jumper cable, and man its heavy, and yes, there is nice thick cooper inside them.
The basic rule is simple, if its cheap its crap.
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S owe have fake fuses, fake jumper cables and 20% of pilots who have no idea what to do when ship happens. Great.
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Have used those, and seen them melt as well. The insulation is foamed polyethylene with an outer skin, so it is lightweight. Melts at about 70C as well, and yes the core is copper coated steel, just like the clamps.
I reused the clamps with better cable, now the cable does not heat up at 200A but the clamps do.
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The total diameter is 11.5 mm
I can't tell the actual copper diameter without taking it apart, but by the looks of it I'd say it looks like 2.5 mm2
The total cable resistance at 100+ mOhms is an order of magnitude more than the battery internal resistance and the resistance of the starter motor combined.
This means that only a third or so of the rated 12 Volts will actually reach the starter motor.
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I truly laughed out loud when i saw that picture.
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Ah, "charging cables", the charge current being simply and reliably limited by the crappiness of the cables, 30 minutes later you can start the car. Also note the poor crinmping technique, the pressure on the metal-metal contact will be low because it's just folded back over the insulation.
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Nice thick cables, capable of handling 1200A, according to the writing on the package
I measured the resistance of each cable and it was 58mOhms, or 116 mOhms total for both cables. These cables can't handle more than 20 Amps tops.
1200 Chinese Ampere = 12.00A >:D
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really cheap
High cost of low prices.
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Yep, that doesn't surprise me at all. There's a lot of cheap ass shit coming in from you know where. I've seen bad connections like that on smaller test leads, however, in order to see how bad the connection really is you have to cut the plastic off with a knife because its a sealed plastic connector. They are hiding a whole lot of shit from people's eyes.
That gives me an idea for a new thread - The worthless connection thread - or something like that. Look for it ...
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How long would the maker of those cables last if they were sold in China. Are those intended for export only ?
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Export only. Remember what happenned to the makers of that melamine contaminated baby formula who sold it inside China. they became organ donors, and the family was sent the bill for this as well.
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How long would the maker of those cables last if they were sold in China. Are those intended for export only ?
There are countless scam artists whose business models rest on consistently scamming lots of people, one at a time.
Yes, tons of such stuff is sold in China too.
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The actual copper is less than 10% of the cable thickness!
I measured the resistance of each cable and it was 58mOhms, or 116 mOhms total for both cables. These cables can't handle more than 20 Amps tops.
This makes them safer than the "better" ones.
Garage owners have better thicker cables, but don't put them in the hands of the ordinary guy.
Due to the bigger resistance, when short circuited, the source car isn't damaged and the sink flame is much weaker.
Sure the car won't start on these cables, but the battery will charge (with a limited current, witch is better)
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Just to answer the earlier question about a non-destructive test. Weigh them. Accuracy is not required. You can tell when you pick them up that they are crap. This does presume that you have calibrated at least once in your life by picking up good cables.
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Well, one thing is explained. I did a jump start last year and the cables melted plastic all over my front bumper, they were probably of similar quality.
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I think we need to put them to a Failure Point Analysis, just to see what they can handle and how long. :-DD
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I did a jump start last year and the cables melted plastic all over my front bumper
High cost of low prices.
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16/25mm is much better
those cables are dangerous measuring end to end on a socket circuit is usually under 1ohm
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I did a jump start last year and the cables melted plastic all over my front bumper
High cost of low prices.
High cost of customers not having the knowledge to determine if a product is shit.
I have discovered Halfords (UK car parts shop) selling fake car fuses. Pack of five for £2.99. Sure, not expensive but you see a brand name and you expect that you can trust them. Nope. This importing deluge needs to be seriously looked at as there are so many counterfeit/fake/dangerous goods entering this country it's forcing legitimate suppliers out of business.
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16/25mm is much better
I have a 4M set I made from some surplus 32mm solar/welding cable. They have no problems starting a 7L marine diesel with no local battery but they weigh a *lot*. I would expect the result of shorting them is instant destruction of the source. They have fully covered clips.
On the other hand, my brother had a cheap-o set not unlike the ones that started the thread. They had transposed the red and black clips on one end, so red cable - black clip. He proceeded to use my mothers Land Rover Disco to jump start his girlfriends Toyota Echo. He gave me a call to ask why the cables were getting so hot. The Toyota survived without issue, but the electrics (which are marginal out of the factory) in the Disco were never the same again.
You get what you pay for. I priced a set of 32mm 4M cables from a boutique 4WD company and they were close to $500. Most of the "affordable" 2AWG sets I've seen in the flesh are a mixture of copper and aluminium wire.
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http://www.wireandcabletogo.com/1-0-Welding-Cable-Class-K.html?gclid=CMDL_ZuZi8QCFZJefgodDCMAgg (http://www.wireandcabletogo.com/1-0-Welding-Cable-Class-K.html?gclid=CMDL_ZuZi8QCFZJefgodDCMAgg)
Thats what I used for my jumper cables. You don't even need the battery in the other car. Just connect them up, turn the ignition, and you are on your way. I used some harbor freight welding ground clamps for it. Works great.
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They are high quality High Voltage Battery Cables for Hybrid cars... like Tesla's..... |O
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They are high quality High Voltage Battery Cables for Hybrid cars... like Tesla's..... |O
A Tesla is not a hybrid and you cannot jump the HV battery pack. You can jump the 12V battery which is needed if you get in an accident (as the high-voltage battery is disabled and will no longer charge the 12V.)
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My jumper leads are the cheap clamps and 00 gauge PTFE covered cable. I have used it to jump start with a totally dead battery, and while the connectors smoked the cable did not.
Did one night jump start an ambulance using the ground power unit, luckily they were close enough so I did not have to move the truck, just unwind the 28V leads and jam the cheap jump leads into the socket ends on the cabling. Lighting on the ambo went from dim to bright instantly, and it started on the first turn of the starter. 24V battery was quite happy with 28V, though I could not see any current draw on the ammeter, full scale is 8kA. Plug some aircraft into it and you do get the peak coming very close to that. Funny enough not big aircraft either. You just need a big jet engine with a starter/generator bolted to the front of it. It can charge at that rate too.........
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How long would the maker of those cables last if they were sold in China. Are those intended for export only ?
There are countless scam artists whose business models rest on consistently scamming lots of people, one at a time.
Yes, tons of such stuff is sold in China too.
A Chinese-Canadian coworker of mine (a software engineer) left China due to the ethical environment there, or lack of ethics. She said there is a saying there, something like, "If the river is too pure, there won't be any fish". That really explained a lot for me, but excused nothing.
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The insulation on that looks like a hotdog...I'd eat it!