In 25 yrs of working on 4-5 cars a day I have never seen a car without Polarity Identification, Industry standards, for goodness sake a watch battery has +/-.If you cant find it, Look Harder its there.The Vast Majority have Red somewhere, but sometimes its faded badly or melted off. But the +/- is on the battery just like the watch battery and has been for decades. sometimes either dirt or a cover is covering the identification but its there. And yes Auto Batteries explode with great force. I left one on a charger once and it blew up after 10 minutes, it sounded like a gun and dented the hood from the inside, I was happy I wasnt next to the car. You can see one explode in the movie Die Hard when the Chaufer Argyle drives the Limo into the Ambulance, its a great shot of a battery exploding, there is video of them exploding that they use in training videos, maybe some should view them if they dont believe experienced people.

yes, explosions in movies are always good examples of how things happen in real life.

And, no I have never seen a battery explode, so since you have, I will take your word on the damage they can do.

trainplanescars wrote:In 25 yrs of working on 4-5 cars a day I have never seen a car without Polarity Identification, Industry standards, for goodness sake a watch battery has +/-.If you cant find it, Look Harder its there.The Vast Majority have Red somewhere, but sometimes its faded badly or melted off. But the +/- is on the battery just like the watch battery and has been for decades. sometimes either dirt or a cover is covering the identification but its there. And yes Auto Batteries explode with great force. I left one on a charger once and it blew up after 10 minutes, it sounded like a gun and dented the hood from the inside, I was happy I wasnt next to the car. You can see one explode in the movie Die Hard when the Chaufer Argyle drives the Limo into the Ambulance, its a great shot of a battery exploding, there is video of them exploding that they use in training videos, maybe some should view them if they dont believe experienced people.

hotrod4x5 wrote:Not all cars have colored cables, and some batteries are mounted and connected in such a way that you can't see the plus and minus symbols, like the Wrangler in my previous post.

I have to agree with Spiky. If you can't figure out standard jumper cables, you probably shouldn't be under the hood to begin with.

aanders1 wrote:
Funny you should ask about the glass...perhaps it is not too large, perhaps it is just underutilized.

Actually, I once wrote a 3-4 page entry on the topic of the half full/half empty glass if you really want the answer to "what would an engineer say"

As a female engineer (of the somewhat fluffier software engineering group), I would have to say that underutilization is an issue with marketing. If they'd understood the specs engineering had given them, we wouldn't be in this position.

Acarolinensis wrote:Having read all the posts, I'm impressed with the amount of misinformation and how strongly the authors believe it to be true. Also having a Y chromosome, I will join in.

First of all the cohort from Minnesota with *LOTS* of practical experience generally know what they are talking about.

IMHO, the best post was from the lady with English car with a positive (chassis) ground. If you blindly connect one cable from chassis to chassis, you're going to have a major problem unless you abort when you notice that the other cable is going from one color to a different color.

So this leaves the mantra of red to red and black to black. You get the lowest resistance connection by connecting to all four battery terminals. By Ohm's law: lower resistance -> less voltage drop -> more voltage applied to starter -> more current flows in starter -> more torque to turn over engine.

But what about hydrogen gas explosions? If you have any kind of breeze blowing during the time from when you open the hood until applying the cables, any hydrogen in area where the cables clip on will be long gone. Remember that hydrogen is much lighter than even helium used in balloons, so the hydrogen is headed elsewhere.

Remember that you need a mixture of hydrogen and oxygen to combust. If you have too much/too little of one/or the other - no big bang. I contend that most battery explosions happen in batteries with very low levels of fluid (electrolyte) that leaves more air space for hydrogen to collect. If this battery is hooked to a running car with the cables reversed, a huge destructive current is going to flow through it. The heat will warp the plates and induce large-scale electrolysis generating both hydrogen and oxygen. The physical destruction of battery contorts it enough to break the circuit through it for an instant, a spark occurs and you now have your weapon of mass destruction. (I would like to hear of any FIRST person reports of battery hydrogen explosions where you are CERTAIN that the cables were attaching correctly.)

So what do you do when when you can't figure out the polarity of a battery? The nice answer is to get out a voltmeter. But nobody has one in their car. The ugly answer is to hookup three cable connections and *LIGHTLY* brush the last one with the smallest and briefest of contact. Note the result and change the connected cable to the other terminal and repeat the experiment. Obviously you want the boring connection. The trauma experienced may motivate you label the battery, even if it's a stranger's. This procedure is not recommended if you don't know what you're doing, but I would guess 100% of today's participants have accidentally clamped their cables down wrong at one time or another and lived to talk about it.

One key to battery cables is to remember that like charges repel each other. Electrons try to get away from each other. Because of this most current flow will be on the surface of a cable. Stranded wire is good because it has more surface area for a given amount of copper and thus more current carrying capacity.
area of a surface = length x width
circumference = 2 pi R = 2R pi = diameter pi
substituting = length x D pi
for any length and pi being constant:
surface area is proportional to diameter
current capacity is proportional to diameter
cable diameter increases as AWG number decreases

This ignores the smaller amount of current that flows inside the cable. It will increase with cross-sectional area:
pi R squared = pi (1/2D)squared
= pi 1/4 D squared
Here conductivity increases by the square of the diameter but you also have to factor in the electrons repulsion of each other. (Physics majors invited to contribute corrections.)

Finally aluminum (Al) cables. The problem is that Al shrinks away from compression connections. The copper (Cu) coating is not thick enough to negate this. I would hope that Michelin took this into account when they designed the cables. Also I believe Cu is also actually a slightly better conductor of heat than Al as evidenced by copper-clad saucepans such as Revere Ware.

Finally close and not so close encounters with electrocution: Ohms law is everything here. V (voltage) = I (current) x R (resistance). What resistance your body presents to the voltage potential across it determines how much current flows through you. If you're in the desert with ungodly low humidity and good, thick desiccated calluses, I'd speculate that you'd barely feel 120 volts. However if you'd just gotten out of a 2 hour soak in Epsom salts, 12 volts might be pretty nasty.

The qualification to this is how much the current is limited to the voltage applied. Batteries and power supplies have internal resistance. 10 volts / 10 ohms internal = 1 ampere short-circuited. If the internal resistance begins to approach the value of the external resistance, the voltage applied will be divided across the two resistances. Less external voltage results in less current flow.

The very high voltage generators mentioned by other posters usually have very high internal resistances by design for safety. Direct current (DC) generators usually collect the charge in a capacitor. Current is the flow of charge so again you want to keep the condenser size small for safety. Judging by the pop I've seen from the picture tubes in old (especially color) TVs (even when turned off for a short period) there is both enough voltage and charge stored to be hazardous to your health. As said before, keep one hand in your pocket.

Personally I use a pair of #6 AWG ~20' stranded copper cables with welding clips that my father made for me maybe thirty years ago for Christmas after a discussion about the dumb gifts men get after a certain age. They've served me and others well through a '52 Ford station wagon, '82 Toyota Tercel and '99 Camry. My impression is that biggest resistance is where the cable clamps onto the battery - getting substantial hard contact is vital.

PS - best humorous post: jumper cables for interrogation and S&M.

And that ladies and gentlemen sums it up for you. Thanks for the post dude, it obviously took some time, well written, deserves a quality post stamp.

I'm amazed no one has mentioned buying a backup battery. For the price of some of the cables people are suggesting you'd be better off going this route. Either keep the spare and recharge it every once in a while or make one battery your starter battery and the other you everything else (maybe with a transfer switch in a pinch). Of course this doesn't help the poor schlep that you may want to help.

Acarolinensis wrote:
...getting substantial hard contact is vital.

Now, where have I heard that before...

rlw999 wrote:Sorry, I don't buy this -- skin effect is not a factor in DC power. But even at 60 Hz AC, the skin depth is 8mm, so unless your cable is over 1/2 inch thick the whole conductor is involved in conduction. The reason they use stranded cable for jumper cables is so it is flexible -- number 2 cable is 1/4 inch in diameter -- not very convenient when it comes time to roll up the cables to stow them away.

I'm pretty sure he was speaking of the cross-sectional area (i.e. the surface area of a cross section).

bsmith1 wrote:Hey! The color-blind are people too!

True...but even a colorblind person can tell the difference between red and black.

tedzilla99 wrote:OK this conversation about the product is all well and good, but I'm the first one to mention the They Might Be Giants reference? Shame on all you Wooters...

Except that MJPErron had you beat by over 6 hours and 4 pages..... Srsly, it was like the 12th post on the I like to smell my armpits, exactly how much did you read before patting yourself on the back???

trainplanescars wrote:In 25 yrs of working on 4-5 cars a day I have never seen a car without Polarity Identification, Industry standards, for goodness sake a watch battery has +/-.If you cant find it, Look Harder its there.The Vast Majority have Red somewhere, but sometimes its faded badly or melted off. But the +/- is on the battery just like the watch battery and has been for decades. sometimes either dirt or a cover is covering the identification but its there. And yes Auto Batteries explode with great force. I left one on a charger once and it blew up after 10 minutes, it sounded like a gun and dented the hood from the inside, I was happy I wasnt next to the car. You can see one explode in the movie Die Hard when the Chaufer Argyle drives the Limo into the Ambulance, its a great shot of a battery exploding, there is video of them exploding that they use in training videos, maybe some should view them if they dont believe experienced people.

I'm pretty sure nobody denied that batteries explode. The typical battery explosion is related to charging a bad battery or mischarging a good one. Those explosions are caused from catastrophic prussure release of oxygen.

The posts questioning explosions are those discussing the chance of a battery exploding during a jump in which the problem stems from hydrogen-oxygen explosions which are incredibly rare around batteries (much less in a battery).

Actually this post makes me wonder if the confusion started way back in the day and the two types of problem and their effects were jumbled together over the years making the current rules commonplace.

All sexism aside, I am VERY good at fixing cars, I've built my own motors, and have my own race cars, and I HAVE made the mistake of crossing the wires- a humbling but human experience.

These wires are probably good for trunk backup, for emergencies-- not perfect, nor meant for regular use, but will get you through in a pinch. As you go up in wire size, the wires get very bulky, heavy, and stiff, and hard to carry around in your trunk or backseat. Those are the ones AAA guy comes with.

For your spouse, or college student, this would work great for emergencies. If you don't own jumper cables, these would be a great first set.

Battery being jumped probably has to have some minimal charge in it for these to work.

edean44 wrote:So am I the only one that didn't read the item title and thought woot was selling roach clips?

Quality Posts: -1

zephalis wrote:I'm pretty sure nobody denied that batteries explode. The typical battery explosion is related to charging a bad battery or mischarging a good one. Those explosions are caused from catastrophic prussure release of oxygen.

The posts questioning explosions are those discussing the chance of a battery exploding during a jump in which the problem stems from hydrogen-oxygen explosions which are incredibly rare around batteries (much less in a battery).

Actually this post makes me wonder if the confusion started way back in the day and the two types of problem and their effects were jumbled together over the years making the current rules commonplace.

I think its simple look at the caution thats on every battery manufactured, Warning, Explosive Hazard, No Smoking,No Sparks, Wear eye Protection. Yes I agree the chances are low that jump starting a battery will cause an explosion. But the Manufacture of the battery is telling you that its possable and has happened, Ive seen people smoking while filling their car with gas, but Ive never seen one blow up in person, but my common sense tells me not to do it. Same principle here I think. And the crash in Die Hard is a real crash, not CG,ya know years ago they actually wrecked the cars. LOL. The problem is in real life the Limo wouldnt have started to drive in the end, cause the battery blew up.But honestly I enjoyed reading all the posts, there are some intellegent people in the world, Id like to learn a little from them all.Also if someone replaces a battary cable when bad with the wrong color, this causes confusion, thats probably how the Wrangler in the post had undecernable cables.And cars with remote mounted batteries usually have a stud covered in red plastic to be used for jumping close to the fuse box, and a place thats says ground to hook the ground to.

this ranks right there with the Egg cooker and the tomato slicer...if you can't figure out positive and negative posts then you should call AAA.

On the topic of battery explosions...I'm not claiming expertise on this one, so someone please correct me if I'm wrong.

I'm thinking that the concern with connecting directly to the negative terminal and igniting hydrogen with a spark is as follows:

When the battery is low in charge, it can also be low in electrolyte between the plates. This allows room for hydrogen gas to form inside the battery. It is this gas inside the battery that can ignite in the case of a spark, rapidly expand and cause the battery to explode.

Hydrogen outside the battery would indeed dissipate too quickly (hydrogen is much lighter than normal atmosphere and so escapes rapidly) so that should not ever be an issue.

I have always heard the thing about not connecting directly to the terminal (although frankly out in the field where we are using car batteries to power many things that are not cars, we connect chargers and the like directly to the terminals all the time.)

I would also be curious to know if people can verify this is a common cause of battery explosions. I certainly know (and can attest) that misconnection is probably a larger cause however [and hence the whole point of today's woot, I suppose]

Other causes I know of are internal shorts developed in the battery and collapsed cells (usually caused by electrolyte issues or metal crystals growing between the plates), punctures, overheating, overcharging, etc.

So...anyone able to verify directly the hydrogen gas thing? You mechanics out there perhaps?

aanders1 wrote:*LOL* I bet! My friends and I have often talked about "Engineering Heirarchy"

In general:
Electricals think they are better than Computers
Computer are defensive and cliquey (they're pretty new)
Mechanicals think they are better than Electricals
Electricals think they are better than Mechanicals
Aerospace engineers look down on everyone.
Everyone pretty much looks down on Civils (sorry, just true).
Industrial engineers are just slightly above Civils to everyone except Mechanicals who view them as just below their own major.
Anyone with "Chem" in the title is viewed as only slightly better than anyone with "Bio" ("Biochem" is the middle ground) and both are looked at as kind of "soft" engineers.
Below that are the "fluffy" engineers like "Human Factors"
And Engineering Management is outright booed to the corner of the cafeteria.

I don't even know if a flow chart could capture all that!

So...yeah. Sorry about the environmental...I've no doubt that got some derision.

P.S. Not trying to offend or say the above are true...but the assumed heirarchy of who generally looks down on who is very much the experience of my friends and I.

Please. Every engineer knows the hierarchy:

Chemical
Electrical
Aerospace
Mechanical
Computer
Civil
Environmental
Household
Sanitation
Industrial

jablomih wrote:Please. Every engineer knows the hierarchy:

Chemical
Electrical
Computer
Aerospace
Mechanical
Civil
Environmental
Household
Sanitation
Industrial

Hmmm...let me guess...you're a chemical engineer 8o).

zephalis wrote:Hmmm...let me guess...you're a chemical engineer 8o).

Nope, EE. Chem E's make more money, but I didn't want to do any of the 3 options available to Chem E's:

1. Live in Delaware
2. Live in Texas
3. Be unemployed.

In for one. Eliminates mistakes when working with a positive ground car.

aanders1 wrote:So...anyone able to verify directly the hydrogen gas thing? You mechanics out there perhaps?

Okay, I looked it back up because it's been a while since I looked at lead-acid chemistry. When a lead-acid battery charges, some of the water in the acid solution gets separated to hydrogen and oxygen via electrolysis. Usually this is later converted back to water catalytically. If the charging is too fast it produces more gas than can be handled and a valve releases the pressure. If the valve is compromised, the pressure builds until the container ruptures.

If the battery is venting and a spark ignites the leaking mixture then the flame will quickly enter the battery and cause the remaining mixture to ignite and explode the battery. This is much worse than just a pressure without the added explosion.

Both situations will cause acid to spray everywhere and even a rupture could cause a spark creating a fireball although this would be less likely.

It is however extremely unlikely that one will have this problem from the short period of time that an informed jump takes place (<5 minutes).

What is a problem is reversal of the terminals for even a short period of time which causes heat and potential boiling of the electrolyte which can cause a rupture of sulfuric acid laden steam.

aanders1 wrote:As an electrical engineer, I must chime in.

Wire gauge is completely relevant. Although the fact that it's aluminum is pretty important too. Really, these cables are not a super choice in either respect even if they will likely work often enough.

Here are some quick assumptions:
1) Starting an average car can take up to 200 CCA (cold cranking amps) - some vehicles even more.
2) Assuming a battery is only low on charge and not completely dead, however, we'll give the benefit of the doubt and say that we need maybe 100 CCA.
3) A car battery of a running (the charging) vehicle is around 13.5-14.5 V from the alternator.
4)So we call up our handy friend the Voltage Drop Calculator (thanks to Gerard Newton) on this page: http://www.powerstream.com/Wire_Size.htm

5) Enter these values:
Aluminum
8 AWG
12 VDC (this implies the approx, not the actual voltage, so it's relevant)
12 (ft)
100 (load in Amps)

That gives you about a 25% drop.
If we start with 13.5V, that's going to give us about 10.5V at the end of the cables.

In general 10.6ish is considered the minimum voltage required to start a car, but it is true that (a) the voltage of a running car is often a bit above 13.5 and also (b) often 10V will do the job...for most vehicles. Some require more(up to 11ish...or more if you have certain hybrids).

So...these cables are good enough to do the job most of the time, even if just barely.

Although, had they been made out of copper, the drop would only be about half that (13%) or had they been the next size bigger wire (6AWG is bigger than 8AWG) it's be about 16% for AL or 8% for copper.

BUT, this neglects the fact that these cables with their smart circuit very likely drop the voltage further. I would imagine at the very least there is probably a diode-like drop of around 0.7V just to keep the current from going the wrong way if you hook it up backward.

In general, jumper cables are sold from 10 AWG to 1 AWG ("light duty" vs. "i want to jump a monster truck from my tank, thank you"), and are more often copper, particularly if they are of good quality. Aluminum is okay though...it just has a higher voltage drop as I said and can also be more brittle (easier to break)...something to think about if you live in a cold area especially where the insulation will be brittle as well and where the voltage drop will be more important (cold batteries do not source current/jump start as well). Also, if you DO put too much current through it, Aluminum has a higher chance of burning up based on its melting point and higher resistance (which makes more heat when you run current through it). Aluminum is also lighter and cheaper than Copper, which is probably why these cables use it.

So...based on that, I'd say these cables are probably okay for most things, but could leave you in a lurch if your vehicle needs more amps (really dead battery, cold weather, really power hungry vehicle, etc).

Oh...and to respond to Captain Wes. I am a woman driver, and I do know how to jump start my car, thank you! (And I knew how to even before getting 2 degrees and a professional certification. So ha.)

You forgot neglected one important point. The running
car's alternator will charge the low battery. Even at 30 amps the charging voltage will be higher than the full charge voltage of 12.6 volts. In other words these cables will allow you to jump start your car as long as the dead battery doesn't have an open
cell and can't accept a charge. Just let the battery charge for five minutes before trying to start the dead car. I used 22 awg copper to jump(charge) a dead battery when desperate, but had to wait about 15 minutes.

People, People, People. A lot of "blah, blah blah" about wire gauge, electricity, etc. The number one thing to know is this: If you drive a car, have jumper cables in the trunk.

If it's THESE jumper cables, okay, if it's the thick copper cables and you know how to use them, great!

Just make sure you have SOME sort of jumper cables available, because there will come the time when you don't and you REALLY need then.

Less than $20 for piece of mind, really.

I think since you're selling jumper cables, you might as well make the minor quantum leap to selling cars.


autos.woot.com? wheels.woot.com?

or just featured once in a blue moon on woot.com


You could pick up some new or slightly used vehicles (leftovers from last model year or something?) and sell them well below MSRP! Plus now that you're with amazon, it'll give the big guys upstairs a way to muscle in on the ebay autos online discount car purchase market.



Today's Woot: 2009 Kia Rio $8999.99

or..

B|O|C - Bodged Old Car. Sell random cars you find at Texan auto lots or just laying around places.

"WOAH I got an '85 AMC Eagle with no hood or passenger side window. Thanks woot!

Aw man, all i got was a '91 celica with a giant woot monkey on the hood.


I got a moped. I got owned by woot! "




FedEx Smart Post: $6.99 standard shipping, because $5.99 would just be outrageous.





Now for something more serious: You guys ever consider selling bicycles once in a while? Like a mountain bike or something for $60?

sl8man wrote:I have to agree with Spiky. If you can't figure out standard jumper cables, you probably shouldn't be under the hood to begin with.

or behind the wheel for that matter...

Finally back from downtime, I wonder if that means something big is in the works? Maybe a Woot!-Off or a Book of Crap.

But deals.woot still down,right??

LukeDuff wrote:Nope.

Do a "return to previous settings" or something. Servers are SUUUUUPER slow. ANd I cant put up my quality post on the iPod.

Cercopithecoid wrote:No more bumpin' the Volksie for me. For you automatic transmission owners, you really should have a set of cables and these are a pretty good deal.

I am old enough to remember when some cars with automatic transmissions had rear pumps (as well as front pumps). My accursed Sunbeam Minx, for example; many times I push started that one (the hand-crank farce was for times it wasn't possible to push-start the car).

I suspect the main reason they included a rear pump was to protect the transmission when the car was being towed. Given the Lucas electrics, I think that "being towed" was how most of those vehicles spent a lot of their lifetimes. (Rear pump eliminates the need to drop the driveshaft (or lift the rear wheels), which in practice... is most likely rarely practiced.)

From my yet to be written magnum opus, "How I Came To HATE Cars"

rlw999 wrote:Even if the cables were stranded to defeat the skin effect, each individual strand would have to be insulated, otherwise they'd all be shorted to each other and act as a single, larger conductor.

Litz wire jumper cables, LMAO! (Laughing because I can actually accept the idea that some marketeeeeer WOULD try pitching such a thing in the effort to tweak market share.)

I'm in for two. Retail for $40 each. Woot on!

I'm in for two. Retail for $40 each. Woot on!

1rudeboy wrote:Probably not a bad product if the concept of polarity is beyond you, but in general IMO, you're better off on 4ga cables for a quicker charge.

Hate to tell you this, but the 8 gauge cable size is quite sufficient for _any_ jump start.

Now if you were going to _charge_ a battery, then you'd have a good point. BUT, they're called jumper cables, not battery charging cables, for a good reason...

ahh I missed out on these. Hope they come back soon! Need to get them for the wife ;)

mndvs737 wrote:Volts don't kill. Amps do. I took a high-voltage shock during a college physics experiment, but the amperage was fractions of a milliamp. Same with a Taser - high voltage for neurological disruption, but very low amperage to reduce the likelihood of defibrillation (probably most likely cause of death from electric shock). On the other hand, a 120V circuit in your house, carrying 12 or 15 Amps, can toast you.

Probably, maybe yes. But you'd have to come to a relatively prolonged contact with the live wire and under most circumstances, that's unlikely. As I've been told (so take with a grain of salt) the most dangerous contact is with relatively low amperage (somewhere around 500 milliamps to just under 1 amp) without regard to voltage because that's where heart arrhythmia is likely to be induced. So the danger isn't that your heart will be shocked to a stop by high amp, or you'll be burned to death by high amp, but that your heart will start to beat irregularly and then stop.

I was under the impression (for maybe no good reason at all) that these cables came with a case to put them in? Jumper cables normally come with a plastic case, these are just sitting in a card board box. So I guess I'm left with deciding if I want to have a cardboard box sitting in my trunk or loose cables.... Anyone else taken off guard by this?

agingdragqueen wrote:Do you mean that they came in the retail box? We did not advertise this as coming in anything other than that box or with a separate case.

yeah, they shipped in a retail box, and we know you guys didn't say they came with a case, but I think we just kinda expected it, or hoped for it. No biggie, no complaints. I still love them. :-)