In this work, an energy-based analysis has been performed for the reset transition of Resistive switching RAM (ReRAM) memristive devices. A voltage ramp input with different slopes has been considered and assumed that these ramps are slower than the physical mechanisms inside the memristor. The analysis has been done in the flux-charge space, instead of the usual voltage-current one. The effects of changing the slope on the reset point have been shown, and a method to estimate the new parameters has been introduced, assuming that the important parameters are those that describe the process in the flux-charge space more than those in the voltage-current domain. In any case, it has been shown that the total energy up to the reset point is dependent on the input ramp, thus strongly hinting at a thermally driven degradation mechanism, as with a slower input signal more energy will be dissipated to the ambient.