doc606 wrote:Not So..... if copper has three times the conductivity of aluminum, a copper wire one third the size of one made of aluminum will carry the same amount of electrons, per unit of time.

(1) Different materials have different conductivity, depending on their chemical structure (electron orbits and what-not) so you can't compare different materials that way.

(2) Most of the charge is carried on the surface of the wire, so even when comparing two sizes of copper wire, for example, you can't simply compare the ratio of cross-sectional area.

(3) You also have to take into account the wire's mechanical and thermal properties, not just its electrical conductivity. A thinner wire may carry the required current -- until it melts due to heating caused by that current.

mjc613 wrote:I beg to differ with your categorization of who knows what about a car's inner workings. If a woman offers to help start your car, she will know how to do it. On the other hand, I have seen men offer to help, because they wanted to be a knight in shining armor, and almost electrocute themselves.

What you meant to say is "These are great for" PEOPLE "who have no knowledge whatsoever of a car's inner workings during an emergency."

I accept your apology.

EXCELLENT post, well said, I posted something similar before reading yours. Looks like lot of PEOPLE took offense to that guys post! I'll bet he will think about it the next time.

showcaller wrote:Well this is just great. Now I have to buy a car.

AH HAHAHAHA....classic....thanks for the laugh!

CoolHand38 wrote:[/i]

Um...You should try to know what you are talking about before correcting others. The car's chassis is tied to the negative potential of the battery - which is not tied to an actual ground. To be ground, the negative would have to be tied off to something conductive driven to a proper depth in the ground. That would be impractical in a moving vehicle. The car is actually insulated from ground by the tires (and road). So, instead of saying put the second black cable to ground, it would be more proper to say put the second black cable to the negative potential of the car chassis (not ground).

Well said! I'd call that a quality post.

Love the comments on the gauge.

Current tends to travel on the outside of a conductor, though it does travel through as well.
A larger gauge has more surface and cross-sectional area for current to travel through, and directly relates to the resistance that wire has to the current. Larger wires, less resistance. Significantly.

Smaller wires means more resistance, which makes the wires hotter. Copper heats and cools quickly, and will get soft before melting into liquid.

And don't forget the conductivity of the metals. Aluminum is less conductive, so that doesn't help matters.

Aluminum is much faster at heating and cooling, and so can more quickly dissipate the heat generated by having a smaller gauge. However, if you exceed what it can handle your wires would not get soft, they would liquify. Aluminum transitions to fully melted a LOT faster than copper. Now THAT would be fun to see.

Bottom line, aluminum is not a good way to go.

robin731 wrote:This woman driver could have used a set of these back when I owned a positive-ground British car and needed to jump it from a negative-ground American car. It took me five minutes to convince the (male) owner of the American car to let me connect the cables hot-to-ground to keep the polarity right.

If I'd had a set of these, I could have just handed them to him, smiled sweetly, and let him save me instead of spending five minutes trying to educate him about auto electrical systems. It would have saved his ego and my blood pressure...

Now THAT should count as a QUALITY POST ! LOL, great story.

These look like a little girls jump rope!

My car is negative ground (62 Land Rover) will these still work?


just kidding... I'd never buy these. Large gauge copper old school cables are the only way to go.

thegodfather572 wrote:so i guess you are saying size matters?

SIZE DOES NOT MATTER, not in my experience. I had a Yukon XL and towed a camper with it. I didn't carry my heavy gauge, long and cumbersome jumper cables with me, because they took up too much room. They were for home use.

I had a very small, light gauge set of CHEAP jumper cables that came in a little vinyl pouch. I used them ALL the time and they never failed. The cables in this Woot are a higher quality and I have no doubt they will work well, AND will be easy to store in the car, which is where they are needed the most.

thegodfather572 wrote:so i guess you are saying size matters?

No, size doesn't matter, as long as you get some! :D

27.99 at amazon. http://www.amazon.com/Michelin-5100-Smart-Jumper-Cables/dp/B002RRZX06

I'm in for one.

Basic ohms law will tell you these won't work for anything more than a 50cc motorcycle. The wire gauage is small so the resistance relatively high, meaning for a depleted battery trying to start a moderate size motor the current draw will be high causing the voltage drop across the cables to be large meaning the battery receives low voltage at the terminals. Low voltage = low cranking speed in a series DC motor. Lesson over :-)

It is a big deal. Actually this is the best daily deals as tracked by dealam.com.

The automatic polarity adjustment is very nice. In my younger days I accidentally swapped polarity and managed to melt the battery terminals to the contact wires in the car I was jumping as well as my car.

arribasn wrote:yup, 8 gauge and 12ft is pretty light duty. May help if you have a small car or battery is not that dead but I roll with at least 6 gauge 10ft cables, would get anything longer unless you get heavy duty 4 gauge ones.

There are two ways to jump a vehicle..a fast way and a slow way. The fast way requires a really heavy duty set of cables. The slow way will work with most any jumper cable set.

The fast way is to hook up the disabled vehicle to the assist vehicle, start the assist vehicle, then start the disabled vehicle. In this case, most of the starting current is coming over the cables, so you need heavy duty (6 gauge or even 4 gauge) cables.

The slow way is to hook up the disabled vehicle to the assist vehicle, start the assist vehicle, and WAIT. The assist vehicle will charge the disabled vehicle's battery (5 - 10 minutes). Then start the disabled vehicle. In this case, most of the starting current is coming from the disabled vehicle's battery (recently recharged). The cables don't need to be heavy duty.

These cables will be fine for the slow way. The copper clad aluminum is no problem. Aluminum is nearly as good a conductor as copper, and the copper cladding on these cables will prevent corrosion (the main problem with aluminum cables).

^^^^what he said^^^^

This is the bare MINIMUM for the fast way. Which is the American way. It will work. If you ever do have to jump a car with these, have the donar car rev its engine during the jump. These are the sort of thing I would buy in a pinch, but if you are actually planning ahead get something decent.

You can get a 4AWG 20 footer for <40 shipped.

enigmachick wrote:Will it jump start my heart?

Blotto quote. Nice.

To the dumb people who are saying the cables are too short, just buy 2 or 3 and daisy-chain them.

srees wrote:Love the comments on the gauge.

Current tends to travel on the outside of a conductor, though it does travel through as well.
A larger gauge has more surface and cross-sectional area for current to travel through, and directly relates to the resistance that wire has to the current. Larger wires, less resistance. Significantly.

Smaller wires means more resistance, which makes the wires hotter. Copper heats and cools quickly, and will get soft before melting into liquid.

And don't forget the conductivity of the metals. Aluminum is less conductive, so that doesn't help matters.

Aluminum is much faster at heating and cooling, and so can more quickly dissipate the heat generated by having a smaller gauge. However, if you exceed what it can handle your wires would not get soft, they would liquify. Aluminum transitions to fully melted a LOT faster than copper. Now THAT would be fun to see.

Bottom line, aluminum is not a good way to go.

Amazon Reviews

Michelin Website

winafew wrote:

I have to disagree with you on this. Alternating current travels on the outside of conductors. The higher the frequency, the greater the tendency. This is because the induced magnetic field (flux change due to changing EMF) drives out the electrons.

However, the current in a jumper cable is direct current, no alternating current. So, except for an initial moment, the current in a jumper cable is pretty much distributed evenly across the cross section of a cable.

These cables will be fine for charging the disabled vehicle's battery so it can start on its own.

But I wouldn't expect them to pass enough current to start the disabled vehicle directly, without waiting for the battery to be charged.

Create a device that caters to the stupid and you'll make a million bucks.

CaptainWes wrote:These are great for women drivers and others who have no knowledge whatsoever of a car's inner workings during an emergency.

As a woman who once had to show a guy how to check his oil and tire pressure, I'm getting a kick out of this.

That being said, this looks like something I'd be interested in.

arroyoko wrote:To the dumb people who are saying the cables are too short, just buy 2 or 3 and daisy-chain them.

Wow, just wow... genius is all I have to say.


You folks might be looking down on people who need this and can't figure out polarity, but I look down upon all of you for driving automatic cars and not being able to bump start your car ;)

NascarDad wrote:I am not sure where the "confusion" comes in. Red positive, black negative. How could someone screw that up?

WhooooHoooo!! My bank account is MUCH better than I thought! Silly me, thought all the balances in red were negative. I can buy these now since my account is positive not negative.. I did have that red/black positive/negative thing screwed up!

renovation wrote:what i dont like is there aluminum clad not all copper.so these are ok for the price but not something to use all the time. price is fair nothing to jump up and down about. if there a big lot im guessing you'll find them on a shelf there or very soon.

If someone uses jumper cables "all the time" on their own car(s), they should be wondering if car ownership is right for them. Running out of battery should be as rare as running out of gas.

So far as price, Whitney asks $47 for these, though they claim to match any lower price we find. Amazon gets $24 with free shipping.

I'm impressed they are 12' long for this price. I'm buying a set for each of my kids who owns a car, and that's 4.

willnott wrote:O M G - claims of shock & electrocution with 12 V DC reveal true ignorance.... on the part of the woot writer as well.... Sheesh - betcha don't even know the difference between volts and amps do ya?

Exactly.
http://legacy.signonsandiego.com/uniontrib/20060527/news_1dd27click.html

zephalis wrote:[quote postid="4050587" user="NightGhost"]Red to red, black to black??? No ground? That's risking a spark which will ignite the battery!{/quote]

Um...try to know what you're talking about before paraphrasing e-how. "black", or negative in a car IS ground. The negative terminal is connected to the car's chassis directly and so they are the same. The only difference is the off chance that the "dead" battery is giving off hydrogen which is very rare. The only reason this chassis connection exists is for liability on the part of the cable manufacturers.

I have no problem admitting when I'm wrong. But "black-to-black" IS wrong - I don't care if the chassis, being ground, is technically "black." Telling someone to hook up "black-to-black" is irresponsible - it is simply asking for trouble.

zephalis wrote:This IS about temporary situations in cars, not permanent situations in houses. And nothing can "creep" away from torque. Torque either exists or it doesn't. You probably mean the connection can loosen over time from the properties of aluminum that has been affixed to a dissimilar metal. This has nothing to do with the 'torque' from the original tightening of the connection.

Also, why would you need jumper cables more than once in 3 years unless you have carp for a car (in which you can't afford cables) or you are stalking people looking to 'start' their 'vehicles'?

yes, I'm aware it's for jumper cables, I was merely pointing out why most people freak out over aluminum and electricity, it has nothing to do with alumumin not being able to handle the amperage given the proper gauge of the wiring for the load it needs to carry, the bad rap it gets is from many house fires in the 70s, the reason for that was creep

"In Materials Science, creep is the tendency of a solid material to slowly move or deform permanently under the influence of stresses. It occurs as a result of long term exposure to high levels of stress that are below the yield strength of the material. Creep is more severe in materials that are subjected to heat for long periods, and near melting point. Creep always increases with temperature."

to me "stress" would be analguous to 'torque' just used a term most would understand but I can keep digging some up to satisfy you I suppose? I added "in this particular application..." meaning use in a car, and yeah using jumper cables is a pretty rare occurance, once every 3 years would be fairly generous... bottom line, you don't want aluminum wiring in you house, but if you needed a dirt cheap pair of jumper cables and you're intimidated by your automobile electrical system and wanted ones that are spoon proof somehow, these would probably be okay.

You need to spend some time, apparently, re-reading what people wrote before you work up your righteous indignation in future.

uskrewed wrote:Wow, just wow... genius is all I have to say.


You folks might be looking down on people who need this and can't figure out polarity, but I look down upon all of you for driving automatic cars and not being able to bump start your car ;)

Today's manual tranny's cant all be bump started due to "advancements" in technology (more like steps backwards).

What most of you who are saying they dont work well dont realize is 99% of you probably try and use the negative terminal or the PAINTED part of the vehicle which is actually the wrong way to jump a vehicle. The engine is the best place for the ground "negative" cables because it gives the best grounding on any vehicle and as thus gives the best jumping ability. Obviously positive still goes to positive.

mjc613 wrote:I beg to differ with your categorization of who knows what about a car's inner workings. If a woman offers to help start your car, she will know how to do it. On the other hand, I have seen men offer to help, because they wanted to be a knight in shining armor, and almost electrocute themselves.

What you meant to say is "These are great for" PEOPLE "who have no knowledge whatsoever of a car's inner workings during an emergency."

I accept your apology.

Totally with you, I (female) am thinking of getting them for my male roommates so when their junkers won’t start they have a foolproof set. Now if only they could figure out how to jump from my car (battery in trunk), I would tell them but the testosterone seems to drown me out. Little old me has also hooked up home entertainment systems, built several computers from parts, fixed lawn mowers, repaired my deck (adding stairs and railing), and simple car stuff, like the brakes, battery, and sensor replacement. Although I admit to dreaming of being swept off my feet by a handyman.

bluejester wrote:Funny post +2

Chances of getting a date -5

He could be in to dudes, in which case the correct rating would be as follows:

Funny post +5
Chances of getting a date +2

Why have the numbers flipped? Its the inverse nature of nature, naturally.

Cusuldor wrote:This is freaking awesome, you have no idea how much your alternator will love you for this... No more guess work.

I don't get it...what was there to guess in the first place? If you really need help using jumper cables, you shouldn't even open the hood.

i cannot endorse these for the youngsters. every high school aged person should experience the smoking cables and looks of horror when a 'helpful friend of a friend' hooks up the jumper cables for you... incorrectly.

NascarDad wrote:I am not sure where the "confusion" comes in. Red positive, black negative. How could someone screw that up?

Because it's not always true. I once owned an ancient Toyota Crapola where the cap on the positive terminal of the battery was black. And yes, I jumped it the wrong way. (and I have a degree in Electrical Engineering) IIRC, the negative terminal was white.

CaptainWes wrote:These are great for women drivers and others who have no knowledge whatsoever of a car's inner workings during an emergency.

If I wanted to talk to my brother when we were growing up, it was under the hood of his car(s). Little did he know that I was actually paying attention. Thanks, bro for teaching me how to jump a car (men who have pulled over to help have tried to do it wrong only to have me correct them - they love that) and how to change a tire.

I find these useful for the aforementioned knights in shining armor that pull over to "assist" me. This way they can save face and I can just stand there all doey eyed.

mhenry1384 wrote:Because it's not always true. I once owned an ancient Toyota Crapola where black was positive. And yes, I jumped it the wrong way. (and I have a degree in Electrical Engineering) IIRC, the negative terminal was white.

very true, in plenty of wiring the white is neutral and the black is actually the hot leg, or positive and contrary to what some ppl have been insisting neutral is not the same as ground. go figure *shrug*

Has anyone else noticed that for two straight days we've been having discussions on electricity (amperage, voltage, resistance, etc.) and even European electricity (Brit Cars, German Cars, etc.)

I think that perhaps one of the Woot! copywriters is getting a degree in Electrical Engineering and he's trying to get us to write his paper for him...

8 gauge aluminum has an ampacity of 40 amps (8 gauge copper can handle 50 amps). These values are well established and can be found in a quick Google search of an ampacity table. A starter can draw anywhere from 60-200 amps. You do the math. They're probably not going to explode or melt, but they'll definitely have some voltage drop at that kind of a load