Scientific measurements on high-power lithium-ion cells require high-precision current sources, such as 80A for charging and discharging. Professional battery test systems include these sources, but they are costly, around $50,000. This paper describes the design of a cell test system with a maximum charge and discharge current of 80A, a current measurement accuracy of 0.1% or 80 mA, and a voltage measurement accuracy of 6 mV. The voltage range of 2.0–4.2 V makes the system suitable for all common lithium-ion cell chemistry types. The hardware components cost $2100 and utilize readily available parts like linear MOSFETs. The cell test system includes current sources with a maximum of 20A each, four for charging and four for discharging. The control software is developed in Simulink. An independent protection system with protection against overcharging, deep discharge, overcurrent, and overtemperature, incorporating an Arduino Nano, prevents cell destruction.