Power supply

The first step when connecting to your instrument is to make sure the instrument has a source of power. Power will normally come from the internal battery pack or from the AC/DC converter that is delivered with most systems. Always perform a visual inspection of any used batteries to check for leaks or other signs of damage.

Internal batteries

The internal battery pack is located inside the pressure case for all instruments except AWACs. Internal batteries enable autonomous deployments of up to a year and also provide backup power in the event of failure of the external supply.  Note that the battery pack inside the pressure case is disconnected when sent from Norway. Please refer to the Maintenance chapter for detailed information on how to connect or change a battery pack. It also ships with an external power supply, which we recommend you use for all but the final testing. If you leave the instrument collecting data, it will continue to run until the batteries are dead. Always make sure to stop data collection when testing is complete. Find more information about the Nortek batteries at our Website.

Typical discharge curves and voltages

We always recommend to work with fresh batteries, to avoid the risk of a unexpected reduced deployment time and therefore the loss of data. Depending on the battery type you are working with, a typical voltage range can be expected for a fresh unit. In table 1 these values are listed for each battery type. Bear in mind that these readings are obtained when the battery is unloaded by testing its charge with a multimeter. 

Storage guidelines

• store batteries in  cool (0°C - 20°C) and dry (relative humidity < 65%) environment
• keep them away from water, direct heat or sunlight to prevent degradation
• ensure that there are no opportunities for the battery terminals to short circuit

If using batteries that have been stored for an extensive period of time, it is recommended verify their initial charge by testing them using a multimeter. Bear in mind, that the charge itself is not a reliable source of information regarding the remaining lifetime of a used or old battery.  Specifically Lithium batteries tend to maintain a stable voltage for an extended period of time during their discharge cycle, before decreasing rapidly. Alkaline batteries show a roughly linear discharge curve as seen on the example of Figure 1. When planning on reusing batteries it is therefore recommended to take note of previous deployments and their energy usage. This will prevent the instrument from unexpectedly running out of power during the next deployment. The power usage for a given deployment configuration and length can be found in the deployment software.

Lithium-Ion batteries are rechargeable and therefore usable for multiple deployments. As with other rechargeable batteries (e.g. a car battery), one has to keep in mind that their capacity will decrease over time. Its lifetime is considerable reduced when completely discharged. A storage charge of 15% - 45% is recommended, which should be checked regularly to prevent a complete discharge.

To avoid starting a deployment with a partially charged battery, our Deployment Software will issue a Warning when clicking Deploy and the connected instrument is equipped with a battery whose charge is significantly lower than stated in the setup. 

💡 NOTE: The Real Time clock (RTC) within the instrument requires power from its own internal battery. This battery can be depleted if the instrument is disconnected from power for an extended period of time. (4 weeks for the Aquadopp and Vector, 1 year for the AWAC as well as the Signature) We commend to place the instrument on external power for 24h before deployment to ensure that the RTC's internal battery is fully recharged. 

External power 

You may also supply power with the external supply that is delivered with the systems, or you can use your own external supply. If you use your own supply, be sure the voltage does not exceed the voltage input range available for you instrument. Check the data sheet for your specific instrument for exact requirements. The instrument will always draw power from the source with the highest voltage. If you use an internal battery to backup data collection, an external supply can provide a higher voltage than the battery pack, which prevents the internal pack from discharging.  Then, if external power fails, the internal battery pack takes over and sustains operation. The power and battery lines are diode protected, so you do not have to worry about wiring the instrument power backwards - this will not damage your instrument.
When connecting and powering both serial and ethernet at the same time, ethernet will always take priority. In such a setup, you will only be able to use Ethernet for communications and data output.

Estimating power consumption

There are a lot of factors that contribute to power consumption, power used to produce acoustic energy is the main contributor, so changing deployment settings like cell size, number of cells, power level and measurement time will change the power consumption.

The instrument software will estimate the power consumption based on all these settings and give you a utilization estimate in % of the chosen battery capacity as well as the power usage in Wh.

Keep in mind that these numbers are theoretical and assume a fresh battery and a normal environment. It is therefore recommended to leave a minor safety margin, although the calculations are on the strict side.

Extending your deployment period

The table below provides an overview of measures you can take to extend your battery life, along with the consequences of each choice on your deployment.

When making changes to your configuration, you can access a detailed summary of the consequences in the "Effect" tab on the right-hand side of the applicable Deployment Planning software for your instrument. This feature allows you to understand and optimize your settings based on the impact they will have on deployment configuration.