I have that happening to a battery after deploying the fairings. It's a probe with a couple of stacked Z200. As soon as the fairings go, the 3rd battery from the top explodes due to overheating. Interestingly it's the one that has two DTS-M1 antennas and two Mk2-R parachutes attached to it. after the explosion the antennas and parachutes are "slightly warm" (according to the F11 overlay). Under the fairing all parts, including the battery, were fine (bright red). "Overlapping" mods: Interstellar FAR Kerbal Engineer Kerbal Joint Reinforcement MechJeb 2