doc606 wrote:any discussion about the wire gauge is not relevant.. this is ALUMINUM wire.
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:
12 VDC (this implies the approx, not the actual voltage, so it's relevant)
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.)