For the first 3 months, we took 1 reading every 15 minutes. Then, last Friday, we increased to 1 reading per minute. The sensor batteries then drained very quickly. The voltage went from 3V to 1.9V in 2 days, then the sensor stopped emitting (see the purple curve).
The main settings of the sensor related to the power consumption are :
1- Power: 4
2- Filtering : yes
3- Delay : 60 s
Do you believe that the emission power can have a significant impact on the life of the batteries that could explain this poor performance? In the case of this plant, the sensors are close to the receiver (maximum 100 feet).
Yes, that will drain battery extremely fast. keep in mind in order to accept the on demand request command the sensor stays on for 1-2 sec and during that time it can consumes upto 120mA current. during a regular sleep interval it consumes around 50uA.
You can reduce the wireless power level to get a bit extra life if you want to use it high transmission rate.
It becomes obvious to me that in order to use these sensors with frequency analysis with frequent readings, I have to use an external power supply.
In order to properly calculate the characteristics of the power supply (voltage, power) and wiring (length, gauge) to be used, can you please give me the characteristics of the current consumed by these sensors (our sensors are dispersed over a very long production line). What is the MAXIMUM current used anytime in mA ? What is the acceptable voltage range (to calculate the allowable voltage drop of the wiring)?
Last little question: Can the external power supply and the batteries work in parallel?
Let me explain: I would like the sensors to be powered by the external power supply all the time. On the other hand, if the current is lost in the factory, and therefore the external power supply becomes unavailable, I would like the sensor batteries to power the sensor while the external power supply is interrupted. Then, when the external power comes back on, the batteries would stop being used.
This would save us from having to add a UPS to our system.