User Manual

Power requirements: Single use batteries
Integrator’s Guide – RIM 801D OEM Radio Modem
14
Single use batteries
When using single use cells, RIM has found that only Alkaline cells provide
the high current necessary for transmission. AA, AAA, and even square 9
Volt batteries provide an excellent power source. The following graph was
generated by a simulator, not an actual radio modem; it depicts the various
transmit capacities of some standard “off the shelf” batteries. The transmit
current used for these tests was 1.25 Amps. In normal operation, the
transmitter will draw less than 1 Amp average.
Number of 1 Second (1 Kbyte) Transmit Cycles Before 6.0V Cuttoff
Cycles
0
500
1000
1500
2000
2500
6-AA
NiCd
(MPT
Pack )
6-AAA
Alk
Prim ary
6-AAA
NiCd
9V Alk
Prim ary
6-
1/3AA
NiCd
9V
NiCd
9V
Carbon
Pri mar y
Figure 3: Battery Transmit Power Comparison
Clearly, AA batteries provide the best transmission capacity. Note that
alkaline batteries are not efficient at high currents, which causes their
transmit capacity to be smaller than expected, but still better than NiCad.
The use of general-purpose carbon-based batteries is not recommended, as
the power supplied will drop to below the minimum required almost
immediately.