@mirodin said in How to power my sensors in a rental?: using normally closed reed switches You can "convert" those by reverting the orientation of the magnet on your door, then adding another magnet (weaker or further away) inside the node enclosure to keep the reed switch closed when you open the door. When the door is closed the reversed magnet on the door will open the reed switch. To do even better you can use : reed switches with 3 leads that work as both normally opened and normally closed switches, and wire them to the 2 interrupt pins. I used that on my first nodes and managed to get reeeeaaaally long battery life on a simple CR2032. When door status changes the node is woken up then you set pin low and current could run only a very short time, you send the message with new status then you activate the other interrupt pin and go back to sleep https://www.aliexpress.com/item/33028519094.html if you're not afraid with SMD there are some ultra low power hall switches, using less than 1uA of current like the DRV5032. 5Pcs/lot 2.5*14mm Reed Switch 3 Pin Magnetic Switch Normally Open Normally Closed Conversion 2.5X14MM DC 60V 4W NO NC $1.47