Which wireless keyfobs are you using? When replacing the battery remove the old battery and let the sensor sit for ~30 seconds before inserting the new battery. When you press a button on the Fob that should clear the Low Battery or you might need to power cycle the system and then see if the message returns. I checked with the eKeypad developer and the eKeypad APP does not read the voltage on the zones so seeing 0 Volts does not mean the voltage is actually 0 V