Previous modeling of thin-film batteries has primarily looked at simple discharge loads. This work examines modeling of mid-frequency dynamic loads with large variation in current during repetitive loading cycles, a type of loading that is very common in microelectromech anical system ( MEMS) applications. Here we show an extension of traditional modeling of thin-film batteries to account for switching and capacitive loading representing piezoelectric or electrostatic microactuation. This model captures behavior at both fast and slow timescales, including effects of short-duration, high-current spikes. We show validation of the model and introduce a cycle projection scheme that allows for over 94% reduction in numerical calculations over a full battery discharge which includes over a million cycles. (C) The Author(s) 2017. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License All rights reserved.