Breaking Badderies: Watt To Do When Batteries Die

 

Walt and Jesse’s Winnebago breaks down in the middle of the New Mexico desert, leaving them stranded with leftover meth- making materials, a battery- dead car, and change in their pockets.

Picture this: you’re stranded in the middle of a New Mexico desert with nothing but a Winnebago, a lot of meth, and change in your pockets. An unlikely situation, but this is precisely the predicament that Jesse and Walt are faced with in the hit TV show Breaking Bad. Only Walt, a chemistry teacher, would have the ingenuity to use spare parts from a Winnebago van and leftovers from a meth-making process to synthesize his very own primitive galvanic cell, right there in the desert! The general process as a whole, according to experts, is reliable and realistic enough to be believable – a feat rarely accomplished in the television business. But exactly how effective would this battery have been in real life? And more importantly, would it be powerful enough to successfully save the two ?

Diagram of a galvanic cell with two electrodes suspended in an electrolyte solution, connected with a conductive wire.

Cobbled together pieces of scrap metal and spare change sounds nothing like your conventional AA battery that you might find in your flashlight or TV remote- and yet, the writers of Breaking Bad have allowed Walt and Jesse to get away with powering an entire van with this seemingly random conglomeration of leftovers . The question remains- did they truly let them “get away” with such a thing, or was the science behind the montage justifiable? Before diving into nitty- gritty of the situation, defining a battery itself is necessary. Batteries are not confined to the ones we recognize from our daily handheld devices- when broken down into its most basic meaning, a battery is a collection of one or more galvanic cells that have the capacity to store and convert chemical energy into a source for electricity as a result of a spontaneous redox reaction. The galvanic cell is an electrochemical unit that is primarily comprised of four parts: a cathode electrode, an anode electrode, an electrolyte solution (fluid that conducts electricity) and a conductor. These units harness chemical energy through a reduction- oxidation reaction, in which electrons are transferred between species. The electrodes are pieces of solid metal that respectively lose and gain electrons through the conductor, which is typically a metal wire connecting the two electrodes. In Walt’s case, he’s not exactly equipped with ideal battery- building materials, but he makes do. Ground graphite and mercuric oxide from the Winnebago’s brake pads serve as the positive terminal of the cell, or the cathode. Zinc found in coins and other spare metallic parts such as nuts, bolts, and washers comprise the anode, the negative terminal of the cell. The electrolyte solution is potassium hydroxide, leftovers from a meth- making process, which is then soaked in a sponge and used to separate the two electrodes. Walt finishes off the makeshift galvanic cell with salvaged copper wire to act as the current- carrying conductor.

Scene from Breaking Bad showing Walt in the process of creating his makeshift galvanic cell with minimal materials at hand.

The battery that Walt constructs is actually a mercury battery, or a mercury cell. Two separate chemical half-reactions take place in the cell, each in either terminal or electrode, thus producing an electric current. On the anode side, an oxidation reaction occurs, which is a reaction in which electrons are lost. Specifically in the battery created in Breaking Bad, the zinc oxidizes to zinc oxide. This is represented by the following chemical equation:

Zn + 2OH- → ZnO + H2O + 2e-

The released electrons from this reaction travel through the conducting copper wire to reach the cathode terminal of the cell, which is where a reduction reaction occurs and electrons are gained. The free electrons that arrive through the conductor are used to reduce mercuric oxide into elemental mercury:

HgO + H2O + 2e- → Hg + 2OH-

The water and OH- ions involved in these reactions are provided by the potassium hydroxide electrolyte. As mentioned previously, the electrolyte is also intended to keep the two terminals separate from one another since the metal ions themselves must not move directly between the electrodes. The porous sponge effectively separates the two terminals . To recap, zinc is oxidized to become zinc oxide while the mercuric oxide is reduced to form mercury, and the cell reaction is Zn + HgO → ZnO + Hg. The reactions at the anode and cathode balance each other out, giving a continuous flow of electrons through the external circuit.

A diagram of a galvanic cell showing the electron transference movement through the current- conductive wire. Mercury and graphite, the positive terminal of the cell, receives the electrons through the wire.

Thus, we can conclude that the technicalities behind the creation of Walt’s battery are credible. However, the functionality of the battery now comes into question- can it actually power their van and get it to start? Walt himself poses this question in the episode, asking: “The only question now is, will this supply enough current?”   Just the fact that he is questioning this aspect of the trial is a step forward for the television industry; the characters are asking the right questions, rather than getting elaborate contraptions to work seemingly by elbow grease and sheer willpower. However, as laudable as this episode of Breaking Bad has been thus far, the reality of the experiment ends here.

Walt’s battery would most likely not supply enough current to jump-start an entire car, let alone a mammoth  vehicle like the Winnebago. This sort of feat would require a much larger source of power, one at least greater than 600 Amps, whereas Walt’s battery probably could only have provided approximately 20-30 Amps of current. Why? Resistance.

Eight galvanic cells are pictured here. Each has its respective terminals separated by an electrolyte- soaked sponge, similar to the potassium hydroxide- soaked one Walt used in his battery. Metallic wires connecting the electrodes are visible.

Based on the potential of a typical galvanic cell and the knowledge that we have that Walt only has enough material to make six galvanic cells, the voltage is enough to have a 12-volt battery. However, resistance must be accounted for. Resistance exists in all conductors and is inversely proportional to current. The internal resistance of the conductor that Walt utilizes in the show would realistically limit the amount of current produced by the battery by a significant amount, resulting in a lack of power that is needed to jump-start the van.

Despite the decisive setback, the writers of this episode of Breaking Bad nonetheless depicted electrochemistry to an impressive degree of accuracy- certainly besting most of its other scientifically- founded contesters in its validity. No matter what the outcome might have been in reality, devoted fans of the show were undoubtedly glad to see Walt and Jesse make it out safely- here’s to hoping for more accurate chemistry coverage in future shows!

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