Dome DMMS1 Motion Sensor (Battery)

Other Devices & Integrations Door Locks & Sensors
#1

Hi so I installed this motion sensor nearly a year ago now and the battery still reads 100%. Could this be accurate? It is installed in a remote location that doesn’t see a ton of motion events, but I find it unbelievable it would still be at 100%.

Anyone have experience with this unit?

#2

It is likely using a lithium battery (CR123?) and the sensor is likely calculating the battery level from its voltage.
The problem is that lithium batteries have almost a step function voltage curve as a function of remaining capacity so the measurement is inaccurate. You will suddenly see it drop to 0 or simply die while the reading has not had time to change yet.
The reference measurement method is meant for alkaline batteries.
NiMH rechargeable batteries have the opposite problem of being lower voltage than alkaline and therefore almost always indicating being low even when they are full.

1 Like
#3

Makes sense. Yes I am using a Li-ion. Guess I will just have to wait and see what happens and how long it lasts.

#4

Mine go from 100% to 1% literally overnight. Not much warning so I keep 123’s in my office for immediate replacements.

1 Like