User Manual

MPR/MIB User’s Manual
Wireless Sensor Networks
Doc. # 7430-0021-06 Rev. A Page 21
6 POWER
6.1 Battery Power
All motes are designed for battery power. The MICA2 and MICAz form factors are designed to
match up with two AA batteries; however any battery combination (AAA, C, D, etc., cells) can
be used provided that the output is between 2.7 VDC to 3.6 VDC.
The MPR500 (915 MHz band), MPR510 (433 MHz band), and MPR520 (315 MHz band, Japan
specific) MICA2DOT form factor is designed to match up with a single coin cell battery;
however any battery combination (AAA, C, D, etc., cells) can be used provided that the output is
between 2.7–3.6VDC.
Table 6-1. Batteries for the Mote Platforms.
Mote Hardware
Platform
Standard Battery (#
required)
Typical Battery Capacity
(mA-hr)
Practical Operating Voltage
Range (V)
MICAz AA (2) 2000, Alkaline 3.6 to 2.7
MICA2 AA (2) 2000, Alkaline 3.6 to 2.7
MICA2DOT Coin 560, Li-ion 3.6 to 2.7
Care should be used in selecting the battery and its capacity to match the energy needs of the
motes and their required operating span. Also make sure that the temperature range and
associated capacity degradation are looked at prior to deployment. Table 6-2 below provides
some useful guidance on current consumption of various system components.
Table 6-2. Current Requirements for the Motes in Various Operation.
Operating Current (mA) MICAz MICA2 MICA2DOT
ATMega128L, full operation 12 (7.37 MHz) 12 (7.37 MHz) 6 (4MHz)
ATMega128L, sleep 0.010 0.010 0.010
Radio, receive 19.7 7 7
Radio, transmit (1 mW power) 17 10 10
Radio, sleep 0.001 0.001 0.001
Serial flash memory, write 15
Serial flash memory, read 4
Serial flash memory, sleep 0.002
Table 6-3 section below provides some useful guidance on how to predict battery life. The
spreadsheet can be found at http://www.xbow.com under the Support section.