DT80 Range Power Information
From dataTaker Wiki (FAQ)
How long will the internal battery last?
Most of the dataTaker DT80 range of loggers include an internal 6 Vdc (See note below) lead acid battery that can be used as the sole power source for the logger. The battery running time will vary according to the capacity of the internal battery, complexity of the program, the volume of RS232/USB/Ethernet communications, power management settings (eg. sleep mode timeouts), sensor excitation requirements, and so on. The following table can be used as a rough guide.
| Sample Rate | DT80/81 (1.2Ahr) | DT85 (4Ahr) |
|---|---|---|
| Continuous | 3 hours | 15 hours |
| 1 second | 6.5 hours | 1 day |
| 3 second | 13 hours | 2 days |
| 5 second | 1 day | 3.25 days |
| 15 second | 3 days | 9.5 days |
| 30 second | 5.5 days | 18.5 days |
| 1 minute | 10 days | 1 month |
| 5 minute | 1 month | 4 months |
| 15 minute | 2.5 months | 7 months |
| 1 hour | 3.5 months | 9.5 months |
Please see the section "battery life" in latest DT80 range user's manual for a detailed description on how to calculate the running time for specific applications.
Note: dataTaker models DT82E, DT80G, DT80L, DT80GL, DT85L and DT85GL do not have a 6 Vdc internal battery
IMPORTANT: These figure assume that the data logger is running firmware version 6.20 or later, as there were many power saving improvements in that release. The latest firmware version can be download from the dataTaker downloads page.
What happens when the internal battery is exhausted?
The logger will detect when the battery is getting too flat to operate the logger and then will force itself into a sleep state. The logger should only be restarted once power is restored. It is possible for the logger to reset if you attempt to wake the logger, by button press or applying a signal to the wake terminal, while the logger is in the forced sleep state.
It is good practice to make your logging JOB the on reset job to ensure that it will automatically start again if the logger reset due to power failure, or other reasons.
With version 8.00 firmware use the Profile StartUp Run=Current_Job or Profile StartUp Run=JobName where Job name is the name of your program. For firmware versions prior to 8.00 use the RunJobOn Reset command.
Can I add a larger external 6V battery?
Yes, an external 6V lead acid battery can be connected and charged by the DT80/81. The external battery should be connected between the 'C' and '-' terminals of the power terminal block.
WARNING: The following points should be considered before using an external 6V battery:
- You should always disconnect the internal battery if using an external battery as connecting two batteries in parallel can cause excessive current flow between them if they are at different levels of charge. You can disconnect the internal battery by not linking B and C terminals, however VBAT measurement is not possible with this configuration. To make VBAT measurement possible you should remove the internal battery (i.e. disconnect the battery at the cables internally) and then link B and C terminals.
- Care must be taken when installing the external battery to ensure it is kept at a similar temperature to the actual logger as the charger is temperature compensated. If the difference in temperature is excessive then the charger will not charge the battery efficiently.
- Larger capacity lead acid batteries take longer to charge. The suggested maximum rating of the external battery is 4A/hr unless an external charging system is used.
Note: The DT85 already includes an internal 4A/hr so there is no advantage in connecting an external 6V battery as suggested here for the DT80/81.
How do I charge a large external 6V battery?
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If the external 6V battery is larger than 4A/Hr then a separate charging circuit must be used. The internal battery must also be disconnected and the B-C link removed. In this configuration, no other power supply should be connected to the DT80 range loggers. |
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How do I use a 12V battery?
| The DT80 range loggers cannot charge 12V batteries so a separate charging circuit must be used. The internal battery may be left connected or can be disconnected if you wish. If the internal battery is connected, it will provide UPS functionality, to allow for short disconnection of 12V power. For example during maintenance. But this configuration will reduce the overall power system efficiency slightly. |
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What happens when the battery is exhausted?
The DT80 range loggers will automatically enter low power sleep mode when the battery voltage drops below a threshold. All data is logged to non-volatile flash memory so no data will be lost. A lithium backup battery maintains date/time and other settings even if the main battery is completely flat. The logger will wake automatically when external power is re-applied.
How often should I replace the Lithium battery?
This depends on the usage of the DT80 range logger. If it is always connected to a power supply then every three to four years. If it spends a long time on the shelf and only used occasionally then one a year would be required. If you are about to deploy the DT80 range on critical tasks and you don’t know the last time the batteries were changed then it would be best practice to replace the batteries, to ensure your data is safe.
How is the battery level displayed?
The standard display (not available with DT81) indicates current internal battery Voltage, current draw and ‘state’ (charging or discharging). Battery and power supply conditions can also be measured, logged and alarmed using as part of the DT80 range logger program. The TEST command also returns battery and power supply operating details to a PC using dEX™ or DeTransfer™ .
NOTE: Battery level in % is displayed but the calculation is only approximate.
What happens if the external supply fails?
The DT80 range logger will continue to run as programmed from the internal 6V battery until the external supply is restored.
NOTE: The logger may go into low power mode depending on the actual application requirements and logger programming.
Can I power from external Battery?
Yes, 10-30 VDC via main power input terminals, or 6VDC Lead Acid via external battery terminals.
NOTE: Note special considerations when using external 6V batteries.
Can I use a non standard external power supply (for example 24VDC)?
Yes, 10-30 VDC via main power input terminals or coaxial connector, approximately 12W minimum rating required.
What is the average power consumption when powered from an external source?
The following table can be used as a rough guide when powering the logger from an external 12Vdc source. Please see the section "Power consumption" in the latest DT80 range user's manual for more detailed information.
IMPORTANT: This table assumes the logger is running firmware version 6.20 or later, which includes various additional power saving measures. Also note that loggers produced before may 2007 will consume an additional 540mW for all scan rates.
| Sample Rate | DT80/81/85 (mW) |
|---|---|
| Continuous | 2300 |
| 1 second | 1350 |
| 3 second | 810 |
| 5 second | 500 |
| 15 second | 210 |
| 30 second | 135 |
| 1 minute | 100 |
| 5 minute | 70 |
| 15 minute | 63 |
| 1 hour | 60 |
Can I connect directly to a solar panel for power?
Yes, however for best performance and battery life, we suggest the use of a solar conditioner or regulator.
How can I reduce power consumption?
Most importantly, you should ensure you are running the latest version of firmware. Firmware version 6.20, and later, include additional power saving measures that can significantly reduce power consumption. Please see the section "Minimising Power Consumption" in the latest DT80 range user's manual for more details on how to reduce the logger's power consumption.
In addition you should also consider the overall power consumption of the whole system you are using (logger, sensors, modems etc) and ensure that devices are only powered as necessary. You can use the relay (1RELAY) on the logger to automatically turn devices on and off as required by the logger's program.
Can the USB port power DT80 range loggers?
No.
Does the DT80 range loggers have a 5VDC supply for sensors like the DT500?
The DT8x Range series 3 has a 5 VDC power supply on the analog section to provide power to sensors.
What other power options for sensors are available?
The DT85 and all series 2 and 3 models in the DT80 range do have a 12V regulated 150mA max switched output.
The DT80 range loggers provide a number of of sensor excitation methods.
- Switched excitation of 4.5V, 200uA or 2.5mA.
- Switched excitation from an external supply.
- Excitation using the Latching Relay.
- 12V regulated 150mA max switched output. (DT85 and all series 2 models only)
- Power output terminal (current limited to 300mA max) that reflects the external power applied to the logger. (DT85 only)
The 6V battery and main power supply may be used for sensor supply if care is taken in regard to ground loops and common mode.
NOTE: Switched excitation is only available to that particular channel while it is being measured. Methods 2 and 3 require an external power supply be connected to the appropriate terminals.
How can I control power to a modem?
The DT80 range loggers can control power to a modem or other external device using the Latching Relay, alternatively using the digital output functions to control an external relay. Additionally the DT85 and DT80 (Series 2 only) can also power low power modems via the 12V output terminal.
NOTE: Output functions can be controlled by Alarms, keypad Functions, schedules or DO and IF commands.
How do I tell if external power fails?
- Visually - the display backlight will switch off (DT80/85) or the Power LED will change from a long 3sec blink to a short 3sec blink (DT81/85). Note that this visual indication will not be available if parameter P16=32 as this disables all LEDs and the backlight to conserve power.
- Programatically - The DT80 has an internal channel to measure the supply voltage. Add the command VExt to your program and the supply voltage will be logged with your data. The internal channels can also be used in alarms
eg.
RA1S ALARM1(VExt<10)"Power failure^M"
- Historically - the times at which external power failed and recovered are recorded in the event log (type UEVTLOG to view)
