Battery packs can be located inside the housing of the instrument or in an external battery canister, depending on instrument type or deployment setup. Working with batteries enables 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. Always perform a visual inspection of any used batteries to check for leaks or other signs of damage.
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.
Alkaline | Lithium | |||
Nominal Voltage | Unloaded Voltage | Nominal Voltage | Unloaded Voltage | |
13.5 V (50,100Wh / 540 Wh) | 14.55 / 14.45 V | 11.7 V | 11.78 V | |
18 V | 19.5 V | 19 V | 19.5 V | |
27 V | 29 V |
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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.