There has been lot of complaints about zkteco biometric attendance machine data reset problem. The problem usually occurs when power is disconnected and device is powered on again. This results in loss of date and time. All other data remain saved and intact. Here is the solution.
Replace two items. One builtinn backup battery and second a small cell same as you find in desktop motherboards. The solution is tested on ZKTeco iface302 biometric finger print and face recognition attendance device.