Does anyone really know how jump starting works?

Question: Who taught you how to jump start a car? Or maybe I should ask this question first: do you know HOW to jump start a car? It’s okay. There are a lot of people out there who don’t know, and I’m sure a good majority of those people (possibly men, ha!) are afraid to admit that they have no clue how to do it. [insert requisite:"That's what she said."]

A press release popped up the other day for these Michelin-branded “smart” jumper cables. What makes them “smart” is that now, one does not need to know the fancy connection sequence of connecting the batteries to safely jump start a vehicle. All one has to do is connect two leads to one battery, and connect two leads to the other battery; a computer that resides inline between the connection leads will automatically sense if the polarities are correct. If they are incorrect, the computer switches them.  You have to trust the cable computer, because those connection leads? They aren’t even labeled positive or negative. No red. No black. All clamp leads are blue.

Recently, MIchelle, brought up the topic of these particular jumper cables on her live webcast show on minglemediatv.com. She was discussing her 16 year-old daughter learning to drive, and recalling all the things one must know in order to drive a car, in addition to  knowing traffic laws and vehicle operation. Drivers must also know how to pump gas, how to change a tire, what to do in case of an accident, and how to jump start a car. Michelle asked her online chat audience if they knew how to jump start a car with normal cables. Most of the participants adamantly stated that “of course” they knew how to jump start a vehicle properly. [Keep in mind that the majority of MissMotorMouth's audience consists of bona fide "car geeks."] Obviously, no one, car geek or not, willfully admits when they can’t do something, and especially not to a large internet audience. [Fact: I am not good at ironing clothes. It's okay, I don't have a large internet audience. It's just between you and me.]

I was in that webcast show audience, and I suppose I am a car geek. [Although, don't tell Michelle; to her, I try to remain a 'novice auto enthusiast.'] I also have a degree in physics. I’ve worked with electricity and electronics for nearly half my life. I know the ins and outs of electricity. Yet, I will honestly admit that jump starting one car with another makes my head hurt. Why? Let me illustrate.

I’m going to pretend I’m you: “you” being someone with possibly no scientific background whatsoever. What do you know about electricity? You know that batteries have a + (positive) side and a - (negative) side. You also know that if you connect a wire between positive and negative, and maybe on that wire is a light bulb, then electricity flows between the two sides, and lights up the light bulb. All that is very true. From that, we can assume that to make electricity flow, you connect + to – , right? Right. I mean, this sort of thing also works with magnets: you know that there’s a North pole and a South pole on a magnet. The North pole sticks to the South pole; conversely, North repels North, South repels South. That’s just like + and – , right? Positive repels positive, negative repels negative. Opposites attract. We all know that. Hell, even Paula Abdul and MC Skat Kat knows this fact.

Now let’s think about that car battery. We have a dead car battery, and we have a charged car battery. We want to somehow get the car with the dead battery started. How do we do it? All we know about electricity –which is not much, because remember, we have no background in science–is that [sing along with me now] “We go together cuz opposites attract!” That makes sense. How do we connect the dead battery and the good battery together? Positive to negative, right?

*BZZZZZ*

Nope.

“But, isn’t that how we get electricity to flow? Positive to negative?” Yes, that’s how we do it, but do we *want* electricity to flow to this battery? This is where it gets complicated, and this is where one needs a better understanding of what is going on with electricity. Electricity is the flow of electrons. [Uh oh. Now it's getting infinitely more complicated.] We need that electron flow (also known as ‘current’) to start our car. The charged battery has plenty of electrons to start the dead car. And as soon as the car starts, the dead car’s alternator will run, and cram more electrons into the dead battery (also called ‘charging’). We need current to flow so we can start the engine, which will in turn run the alternator, which will then charge the dead battery.

What do we do? We have to know a little something about electric circuits and diagraming them. And you, person who said “Of course I know how to jump start a car!”, thought this wasn’t rocket science! I’m going to skip the physics/electrical engineering lesson and just say “We want to put the charged battery and the dead battery in parallel in our circuit.” That is what we are doing when we jump start a car. And how do we put two batteries in a parallel circuit? Positive connects to positive, negative connects to negative. You’re saying to yourself “But…electricity flows between a positive and a negative, how does it flow here?” Oh, it’s flowing, but you have a much more complicated circuit diagram than just a light bulb on a wire connecting + and – . See? It IS rocket science. Well, not really. It’s just counterintuitive to what we know or have been taught about electricity.

[Note: I can hear a few of you whispering (or shouting) "It's not positive to positive, negative to negative! It's positive to positive, negative to solid metal grounding material on the engine!" That's right, that's what they tell you. But the negative battery terminal is connected to the chassis; the engine is connected to that same chassis. Most everything metal in the car is connected to the negative terminal of the battery. So why do they tell you to connect the negative end to ground? It's mainly to reduce sparks when connecting  the clamp. That's all.]

Back to the question: What about these “smart” jumper cables? Is this a good thing or a bad thing? As a person who has a science background, and knows all this stuff, I agree with Martha Stewart. I know how to connect batteries; I know how to make complicated circuits; I know how to make grapes spark in a microwave oven; I know lots of complicated and weird science
things. But I tell you honestly that whenever I need to jump start a car, I have to stop and think for a minute, and run the circuit diagrams in my head. For people with no circuit diagrams in their head, it’s a game of chance. And that game can have some deadly consequences.

Jump starting a car is complicated; it’s usually during an emergency when we need to do it. In emergencies, one should be able to do what they have to do quickly, and they should not be required to stop to think long and hard “Am I doing this correctly?” I’m sure there will be people arguing “Drivers should know how to do this with regular cables!”, and I completely agree. Parents/Guardians: teach your 16 year-old how to properly jump start a car with regular cables; explain to them (if you can, maybe with help from the interwebs) about positive and negative. And electron flow and current. And series and parallel circuits. Make them jump start a car with regular cables. Watch them freak out when they see sparks. Then…go get them these cables, and put them in the trunk of their car. That’s how most of life works. You learn something the hard way, just so you know/experience it, then later, someone shows you the easy way. That’s how we learn. It reminds me of how I learned to take a derivative in calculus by calculating using a limit, then learned the “easy way” of moving the exponent…what, you don’t know how to do that? A new, exciting blog post coming right up!

Carl Acampado is a product+graphic designer/physicist/cookie baker/road cyclist/novice auto enthusiast who wastes lots of time on Twitter and seems to write a lot of posts about design and Apple products on his blog. No one knows why.