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Enabling Asset Security & Management BPS.0707.01P Batteries and Power Supplies.

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Presentation on theme: "Enabling Asset Security & Management BPS.0707.01P Batteries and Power Supplies."— Presentation transcript:

1 Enabling Asset Security & Management BPS.0707.01P Batteries and Power Supplies

2 Enabling Asset Security & Management BPS.0707.01P 2 Powering Your Application  Can be a complex decision  Many factors to be considered  Technical  Commercial  Operational  Support  The success or failure of your application can be affected

3 Enabling Asset Security & Management BPS.0707.01P 3 Power Supplies  Available sources of power  AC source  Batteries  Vehicle switched or unswitched?  Solar cell  Standby requirements  Multiple sources  Operating modes  Differences between normal & standby operation

4 Enabling Asset Security & Management BPS.0707.01P 4 Guidelines  Optimize for low power operation  Exception based reporting  Power GPS on demand  Geofencing & distance based scripts require the DMR to be constantly receiving GPS positions  Sleep modes  Minimize receive periods to minimize power consumption

5 Enabling Asset Security & Management BPS.0707.01P 5 Power Consumption  DMR-200 power consumption  Receiving0.8 W  Idle0.25 W  GPS1.2 W  Transmitting10.2 W  Heater (activated at -25°C)2.8 W  Sleep (@ 12 V).005 W  I/O power consumption  Displays, keyboards, etc.  Sensors, actuators, etc.

6 Enabling Asset Security & Management BPS.0707.01P 6 Typical Power Consumption  Normal Operation  ~ 1 Watt (~2 Ah/day @ 12V)  GPS push to fix  ~ 0.5 Watts (~1 Ah/day @ 12V)  Low Power (no listen)  1 hour reporting~ 0.1 Watts ( ~0.2 Ah/day @ 12V)  4 hour reporting~ 0.03 Watts ( ~0.05 Ah/day @ 12V)  8 hour reporting~ 0.02 Watts ( ~0.03 Ah/day @ 12V)  1 / day reporting~ 0.01 Watts ( ~0.02 Ah/day @ 12V)  Low Power (10 minute listen)  1 hour reporting~ 0.2 Watts ( ~0.3 Ah/day @ 12V)  4 hour reporting~ 0.04 Watts ( ~0.1 Ah/day @ 12V)  8 hour reporting~ 0.03 Watts ( ~0.05 Ah/day @ 12V)  1 / day reporting~ 0.01 Watts ( ~0.03 Ah/day @ 12V)

7 Enabling Asset Security & Management BPS.0707.01P 7 Calculating Power Consumption  Determine sequences of operation for the DMR-200 terminal  # of terminal originated messages a day?  When can terminal receive a message?  How long will terminal be in sleep mode?  Will terminal be in -25°C environment?  Will digital open collector output be used?  Calculate power consumption for operating period

8 Enabling Asset Security & Management BPS.0707.01P 8 Example  Transmit 1 message per day  Listen for 10 minutes after each transmission  Shutdown the rest of the time  Sequences  Acquire bulletin board  Acquire GPS  Acquire traffic channel  Monitor bulletin board  Transmit  Listen for 5 frames  Sleep

9 Enabling Asset Security & Management BPS.0707.01P 9 Power Calculation – 1 Tx Per Day Time (seconds)Power (Watts)Energy (Joules) Acquire bulletin board 1400.9126 Acquire GPS 600.530 Acquire traffic channel 240.922 Monitor bulletin board 600.954 Transmit 81080 Listen for 5 frames 1200.9108 Idle5300.25133 Sleep 854580.006513 Total864000.0121065 Average current @ 12V (Amps) 0.001 Amp hours per day 0.025

10 Enabling Asset Security & Management BPS.0707.01P 10 Power Calculation – 2 Tx Per Day Time (seconds)Power (Watts)Energy (Joules) Acquire bulletin board 1400.9126 Acquire GPS 600.530 Acquire traffic channel 240.922 Monitor bulletin board 600.954 Transmit 81080 Listen for 5 frames 1200.9108 Idle5300.25133 Additional transmit cycle9420.586552 Sleep 845160.006507 Total864000.0191611 Average current @ 12V (Amps) 0.002 Amp hours per day 0.037

11 Enabling Asset Security & Management BPS.0707.01P 11 Battery Technology Selection  Primary - non rechargeable  Secondary - rechargeable  Considerations  Service life  Operating mode  Frequency of reporting  Operating environment  Temperature range  Available power sources  Charge requirements

12 Enabling Asset Security & Management BPS.0707.01P 12 Primary Batteries - Non rechargeable  Carbon Zinc  Low power density & short shelf life  D cell – 8Ah @ 1.5V  Lowest cost  Alkaline  Moderate power density & 5 year shelf life  D cell – 18 Ah @ 1.5V  Moderate cost  Lithium Thionyl Chloride  High power density & 10 year shelf life  D cell – 13 Ah @ 3.6V  Highest cost  Must use high rate versions for peak tx currents

13 Enabling Asset Security & Management BPS.0707.01P 13 Secondary Batteries - Rechargeable  Lithium-ion (Li-ion)  Highest power density  Highest cost  Stringent charging requirements  Good self-discharge rate  Small form factor  Limited peak current capability  Sealed Lead Acid (SLA)  Most popular – well understood  Good cost performance trade- off  Easier to recharge  Lowest power density  Lowest self-discharge rate  Heavy  Nickel Metal Hydride (NiMH)  Middle of the road  Highest self-discharge rate  Nickel Cadmium (NiCd)  High current applications  High self-discharge rate  Memory effects if not managed correctly

14 Enabling Asset Security & Management BPS.0707.01P 14 Solar Cells  Ensure adequate output to recharge batteries under all conditions.  Cloudy days  Short winter days  Accumulation of dirt/snow/debris  Orientation to the sun  Ensure battery capacity to cover long nights and cloudy days  Charge controller generally required  Relatively expensive & fragile

15 Enabling Asset Security & Management BPS.0707.01P 15 Things To Watch Effects of temperature  Many batteries lose capacity @ high or low temperatures Minimum battery voltage at end of life  Ah ratings usually specify a minimum voltage Peak current  Many technologies typically cannot deliver the peak current required during transmit Out gassing  Batteries inside a sealed enclosure can explode Accidental discharge  A lot of energy in a very small package  Product liability issues

16 Enabling Asset Security & Management BPS.0707.01P 16 Specification Checklist - 1 Voltage  It is important to know not only the nominal voltage, but also the minimum and maximum for the application. As an example, a 7.2 volt nominal nickel metal hydride pack will vary from 6.0 volts in a fully discharged state to 9.6 volts at the end of charge. Discharge Current  Both the average and maximum discharge currents are needed to specify the proper battery. Most often, the average current determines how large the battery must be to operate the device for a given amount of time. But in some cases there are intermittent high loads, and the maximum current requires a larger battery for the device to operate at all. Cycle Life  If the battery is rechargeable, the number of charges and discharges required over the life of the battery will help determine the ideal chemistry and capacity.

17 Enabling Asset Security & Management BPS.0707.01P 17 Specification Checklist - 2 Service Life  For a non-rechargeable or a backup battery, the size and chemistry will be determined by the required life, as well as the discharge and temperature profiles. Cost  A technically ideal battery could be cost prohibitive. Note, however, that a more expensive battery can sometimes pay for itself several times over in the form of reduced replacement costs and/or better performance. One-Time-Use or Rechargeable  One-time-use or primary cells, once discarded must be replaced with a fresh battery. Rechargeable or secondary cells can be used many times, but require a charger. Charging  Improper charging is the leading cause of early failure in rechargeable batteries. A better charger will often pay for itself in increased performance and reduced replacement costs.

18 Enabling Asset Security & Management BPS.0707.01P 18 Specification Checklist - 3 Weight & Dimension  Cells of various chemistries are made in a wide variety of sizes, and custom battery packs offer even more flexibility. Note that a smaller, lighter battery with the same energy usually costs more than a larger, heavier one, and even if money is no object, there is a limit to how small and light a battery can be. Temperature  If your product will be used or stored in hot or cold conditions, battery performance and life could be affected. Low temperatures compromise performance, while high temperatures dramatically reduce the life of cells. Storage  Duration - Consider not only inventory turnover, but how long the batteries will spend in the supply chain and in your customer's inventory before being used or recharged.  Conditions - What temperature and moisture conditions will your battery be stored under?

19 Enabling Asset Security & Management BPS.0707.01P 19 Specification Checklist - 4 Self Discharge  This is a measure of how quickly a cell will lose its energy while sitting on the shelf. Note that higher temperatures will significantly reduce the shelf life of any battery.  Primary Batteries:  Carbon2.5 years  Alkaline5 years  Lithium10+ years  Rechargeable batteries:  Lead acid6 months between "top off charges“  NiCds1 year between charges  NiMH1 year between charges  Lithium1 year between charges


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