XBee Sensort ZB Bat/L/T/H battery life

I was surprised when my batteries started running out after only three months operation. Here’s my setup as recommended in the Wiki:

SP 3E8
SN 6

The sensor sleeps correctly for a minute, then the LED blinks about 5-7 times and the cycle starts all over again.

The coordinator is configured as follows:

API mode 2
SP 400
SN 6

I am surprised how long the LED on the sensor blinks, a couple of seconds. The only messages received by the coordinator are the data packets once a minute with sensor data.

I had expected a battery life of at least a year, hopefully several.

Originally I left the sensors in the default configuration and polled them. The LED would blink rapidly except when the poll was happening, when it would blink more slowly. The battery life seemed about the same, about three months.

According to the Wiki the scheme using sleep mode should be much more efficient.

Any clues?


seems like xbee sensor wake time is more. Have you checked battery life calculator on digi’s website?

Can it be ST (Time before sleep)? I see it defaults to 5 seconds which is a long time to keep the module in high power mode. I think I’ll try to reduce it, first to one seconds and later to 250ms.

No, I looked at the spreadsheet and found it a bit intimidating. I guess I should give it another shot.


I have to say the battery life calculator is pretty useless. It assumes just three modes: sleep, send and receive, and doesn’t include idle, which is what I believe is the cause of my problems. In my scenario I believe it currently sleeps 5.125 seconds, during which the drain is 15mA, one third of the receive drain. Also, figuring out exactly how much data is received and transmitted isn’t trivial since there are multiple packets sent and received for each transmit of sensor data.


I changed ST from 5 seconds down to 1 second and the awake time dropped correspondingly. Hopefully this change will increase battery life considerably. My guess and hope is that it will be about 4 times as long as I experienced before the change.


There is no idle mode for xbee modules