What happened in the show: Relatively early on during Jesse and Walts meth cooking career we see the duo take the RV into the middle of the desert and cook for a long weekend. Jesse leaves the key in the ignition for safe-keeping, failing to notice the dashboard indicator lamp lights up. The lamp drains the RVs battery completely, leaving them stuck. After several squabbles, Walt realises he can make a mercury battery using chemicals, coins and galvanised metal. The battery works, the RV fires up, and theyre able to drive back to civilisation. Could it really happen? No, not at all. Sure Walt could have made a homemade battery given the tools he had available to him; the coins, nuts and bolts he used provided zinc, which serves as the anode. The potassium hydroxide used in the pairs meth making acts as an electrolyte to conduct a charge, and the cathode is mercury. Unfortunately, even though Walt made multiple batteries they would never have been powerful enough to get the RV back on the road. The engine would have required power of around 200-300 amps to get it started, and a homemade battery would generate an estimated 3% of that at most. In the real world Jesse and Walt would have been stuck in the desert with no water and no hope.
