In battery chemistry, “thermal runaway” describes a tiny cell that, once overheated, triggers an exponential heat cascade, destroying the whole pack. The physics is simple: each extra ampere of current raises temperature, which in turn raises resistance, producing even more heat—a self‑reinforcing loop that spirals out of control. The same feedback exists in product roadmaps: every added feature increases code complexity, testing scope, and integration risk, which then amplifies the effort required to ship the next feature, creating a hidden acceleration toward instability.

Samsung’s Galaxy Note 7 illustrates this perfectly. In 2016 the company swapped its original lithium‑ion cell for a higher‑capacity version to meet a tighter launch window, then added a third‑party power‑management chip to squeeze out more performance. The cumulative changes raised internal resistance just enough to push the cells into thermal runaway during normal charging, leading to a global recall that cost the firm over $5 billion and shattered consumer trust.

The lesson is not that any extra feature is fatal, but that each addition carries a marginal heat that, once summed past a critical threshold, ignites a cascade far larger than the sum of its parts.