Batteries, Sparks, and Dummies

Don't connect jumper cables like this!

It is said that is it better to keep your mouth shut and be thought an idiot than to open it and remove all doubt. At least that's what they used to say before the internet; now they say, "On the internet, nobody knows you're a dog." That anonymity, combined with good old-fashioned greed, let a lot of people write utter bullshit in the guise of "answers" to burning questions. Yep, we're talking about eHow.com contributors and their output; contributors like journalism graduate (of the Ernie Pyle School of Journalism? what a tragedy!) Kristine Brite, who it appears skipped every science class along the way to her degree. We know this because of what she said in "Why Does the Battery Cable Spark When Placed on the Post?" for ItStillRuns.com.

So, why does the cable spark? It's not that difficult to understand if you've passed high school physics: the spark happens when an electrical current jumps the gap between the post and the cable to complete an circuit. The size of the spark depends on the charge in the battery and a few other variables like humidity. The spark itself isn't electricity, it's a flash of light caused by heating the air in the gap. In other words, no big deal: much like static electricity.

Brite, however, is having none of that. Nope, according to Kristine,

"The spark comes from the metal's reaction to the battery. If the cables are connected normally, sparking is not dangerous to people or the vehicle."

After absorbing the inanity (not to mention dumbassery) of the first sentence, keep your eye on the second sentence. But back to that first: "the metal's reaction to the battery"? WTF is that supposed to mean, that sparks are some sort of chemical reaction? That the metal is jumping away in fright? We await further explanation...

...which is not forthcoming. Nope, Kristine explains that

"Items... such as the radio and clock... attempt to draw power from the battery. This means the electrical system is drawing current... Sometimes this can cause the battery jumper cable to spark when it's connected to the battery post."

Umm, yeah sure, Kristine. In point of fact, regardless of whether a single "item" in the car is drawing current, closing the circuit by attaching the second cable (which, by the by, isn't a "jumper cable") to its post can cause a spark. And then she explains that

"The battery cables can spark if the cables are installed in the improper order. When attaching the battery cables, place the positive cable on first and then the ground cable. Do not allow the cables to touch on the free end not yet hooked into another battery while the cables are connected to the first battery. Also, the ground, or negative cable, should not be touching anything metal while the positive cable is hooked up." Sorry, Ms Brite: the order makes no difference. The cables will spark like all hell if they're attached to the wrong posts, which is why both the cables and posts are clearly labeled and the posts are sometimes of slightly different diameters, but the order ain't all that important. That second sentence? It appears to have something to do with jump-starting... though we're not sure what. And that third sentence? It's absolutely idiotic -- and yet Brite goes on, like an Energizer® bunny...

"Sparks from the battery cables present some dangers. The battery is filled with explosive gases. The spark could potentially light the gases, and the battery could explode. Also, anyone touching the cables could get shocked from touching them."

But wait: Brite said in the introduction, "sparking is not dangerous to people or the vehicle" before: which is it? First, however, let's disabuse you of the notion that a "battery is filled with explosive gases": that's absolutely untrue. Rapid charging of a lead-acid battery can cause hydrogen gas to form and collect near the top of the battery, and it is explosive. That's why, when using jumper cables, you don't connect the black cable to the battery of the car being charged -- you ground it somewhere else. As for getting a shock, maybe, just maybe, someone might get a small charge from holding the terminals; but not from touching the (insulated) cables.

In a mere 200 words Brite manages to exhibit an astonishing unfamiliarity with chemistry, physics and the basic workings of her car (or anything with a battery). Is it any wonder that she's today's recipient of the Antisocial Network's coveted Dumbass of the Day award? Of that, there's no doubt.

NOTE: This information presupposes that you haven't been trying to install electrical parts in your vehicle such as a starter or alternator. If you get a big spark when you try to reconnect the ground cable (you didn't need to disconnect both to do the work), you may have a short in the system caused by incorrectly wring the new part.

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