Overdischarge effects on cycle-life and thermal stability of a commercially available Li-ion cell (rated at 780mAh) were investigated. Cells were overdischarged and kept at 2.0, 1.5, 1.0, 0.5 or 0.0V for 72h (3 days) and then cycled five times (discharge to 3.0V at 0.4A and charged to 4.2V at 0.8A). This process was repeated five times. The cells overdischarged between 2.0 and 0.5V experienced irreversible capacity losses of 2–16%. The same cells lost between 8 and 26% more capacity after they were cycled 100 times between 4.2 and 3.0V at 0.8A. Behavior of the cells overdischarged to 0.0V was unpredictable. Some cells lost nearly 65% of their initial capacities after 15 days of being kept at 0.0V, and others failed in different stages of overdischarging to 0.0V. Overdischarging to 0.5V had minimal effects on thermal stability, overcharge performance and a.c. impedance, but led to considerable swelling of the cells. Overdischarge to 0.0V caused cell thickness and a.c. impedance to increase by ∼70 and 250% of their initial values, respectively. This article addresses concerns that overdischarging of Li-ion cells below 1.5V may cause capacity losses and/or thermal stability changes which could impact tolerance to abuse conditions.