I have a 345mhz Qolsys panel. Three of my door contacts are reporting low battery. I changed the batteries. Each new battery was also tested before installation. Two door contacts continue to report low battery. The third contact returned an end of low battery report, about two hours later the panel reported that it too has reported a low battery.
The contacts function perfectly and the panel notifies me when the doors are opened and closed.
When replacing the battery, you need to let the sensor de-energize. You need to wait about 30 seconds before inserting the new battery. When replacing the battery, you can also press the tamper button a few times without any batteries in it to help with the process. If the sensor does not fully de-energize, there can be a low battery ghost signal on the sensor that does not clear even with a new battery.