User Manual

Power requirements: Automotive supplies

RIM 801D OEM Radio Modem – Integrator’s Guide

Automotive supplies

If you plan to power the RIM 801D from an automotive supply, extra

protection must be included to protect the radio modem from the intense

power fluctuations experienced when the automobile is started. A circuit

comprising inductors, transorbs and voltage regulators should be used to

ensure the radio modem is protected from these power fluctuations.

Commonly, in automotive applications, voltages may be as high as seventy

volts on the battery, especially during starting. Commercial automotive

adapters are available that will safely convert the 12 volt automotive supply

to a regulated 8 volt supply suitable for operating the RIM 801D radio

modem.

Supplying the RIM 801D with more than 10.5 volts will damage the

modem.

Rechargeable batteries

For battery-operated applications requiring a wide operating temperature,

RIM recommends using Nickel-Cadmium (NiCad) batteries to power the

radio unit. Nickel-Metal-Hydride and Lithium Ion cells may also be used,

but the cell temperature specifications may inhibit operation at temperatures

below freezing.

The cells chosen should be able to meet the load specifications of the RIM

801D. RIM has found that a six-cell AA NiCad battery pack provides a

good balance of size and performance. For space-restricted designs, AAA

NiCad cells will require about one-third the volume, but provide only about

one-fifth of the transmit time.

Using cells smaller than AAA is not recommended, as these cells do not

generally have the capacity to sustain a high rate of transmission.