An old problem returns to the automotive market, thanks to innovation.
For those of us who hunt down classic cars, often looking for those examples which have sat in a garage, barn, or worse an open field, rust is simply a reality that must be dealt with. However, for most people who own cars which are at most a decade and a half old, having floor pans, quarter panels, and other parts of a vehicle rust out is a fading memory, if not something completely foreign. However, when it comes to electric cars, rust is quite the problem.
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It all comes down to one factor: battery weight. As automakers try luring consumers into buying EVs, one method that’s often deployed is to create models with phenomenal range. That, of course, means bigger batteries and those by nature are heavier. To help counterbalance that, automakers have turned to light metals, shaving some weight off the rest of the car design.
The problem is those light metals can rust quite easily. Not only do they have to be protected against self-corrosion, they can be victims of galvanic corrosion as soon as they come into contact with any other material with a higher negative electron potential.
But wait, there’s more. Because of this heavy emphasis on lightweighting to counterbalance big, heavy EV batteries, voids and gaps in vehicle structural components are common. Automakers will fill those with insulation foam to cut down on road noise, but that also binds moisture to the metals. Over time, rust will spread like a cancer, hidden from view until a serious problem finally manifests.
Rust repair can be frustrating and expensive. Sometimes, entire structural members or body panels must be cut out or unbolted and replaced. The thing is if the same methods are used to reassemble the electric vehicle, rust could become a problem yet again down the road. And rusting structural components absolutely disintegrate in a crash, presenting a safety risk.
This rust problem is just another unintended consequence as the automotive industry pushes toward electrification, but it is a vexing one.