FY Supercapacitors KEMET FY Supercapacitors feature a 5.5VDC operating voltage (maximum) and operate in a wide temperature range of -25°C to +70°C. These maintenance-free devices are also known as electric double-layer capacitors (EDLCs). The FY series offers high reliability against liquid leakage. KEMET FY Supercapacitors are suited for low-voltage DC hold-up applications such as embedded microprocessor systems with flash memory.