Lot of battery Z-Wave modules seem to reduce things down to once every 4 minutes or less. Even when lowering the variable ID setting it can refuse to accept it (such as the Aeon-Labs 4-in-1 sensors I got). Changing the value can be extremly tricky as well, as the module needs to be awake for this. On the Aeon one the manual states to press Z-Wave button 3x fast to keep it awake for 10 minutes, but this failed for me as well. Finally in a desperate move I pushed the little button on the sensor right after sending the variable update and that's when it finally accepted it when I double-checked via "Get".