SonTek/YSI Argonaut-XR Technical Manual - HydroScientific West

SonTek/YSI
For most autonomous deployments, the combination of averaging interval and sample interval
determines the instrument duty cycle and thus the total battery life. Burst sampling (collecting a
number of samples in rapid succession followed by a sleep period) lets you monitor both the
short-term and long-term variations in flow, while maintaining a low, overall duty cycle. Burst
sampling increases the amount of data recorded and may encounter limitations on storage space.
The increased data storage requirements for burst sampling may have a significant impact on
field operations. For details on storage requirements, see §7.2.
7.2. Calculating Battery Life and Data Storage Requirements
During continuous data collection (pinging once per second), the Argonaut MD has a mean
power consumption of about 0.10 W. The Argonaut XR and SL have a mean power consumption
of 0.2-0.3 W depending on the measurement volume size (larger measurement volumes use more
power). These values assume that battery power is fed through the direct battery power
connection to the Argonaut processor rather than through the external voltage regulator (§6.1).
Power consumption through the voltage regulator is typically 0.3-0.4 W for the Argonaut MD
and 0.6-0.7 W for the Argonaut XR and SL.
The Argonaut MD alkaline battery pack outputs 10.5 V with a nominal capacity of 35 Ah, and
the lithium pack outputs 10.8 V with a nominal capacity of 52 Ah. When calculating battery life,
SonTek recommends using 80% of the nominal capacity; this allows for temperature variations
(nominal capacities are for 20°C) and a reasonable safety margin. Thus, alkaline and lithium
packs have working capacities for the Argonaut MD of 295 Wh (0.8 * 10.5 * 35) and 450 Wh
(0.8 * 10.8 V * 52 Ah), respectively. This is sufficient for about 120 and 190 days of continuous
operation (using 0.1 W power consumption).
The Argonaut XR alkaline battery packs output 12 V with a nominal capacity of 42 AH; lithium
packs output 10.8 V with a nominal capacity of 112 Ah. These packs have working capacities of
400 Wh and 960 Wh respectively. This is sufficient for 55-83 and 130-200 days of continuous
operation (using 0.2-0.3 W power consumption).
In many situations, the Argonaut can use a reduced duty cycle to conserve battery power and
extend deployment length. For example, the Argonaut can collect one 5-min average sample
every fifteen minutes for an effective duty cycle of 33%. When not actively collecting data, the
Argonaut consumes less than 1 mW of power; a 33% duty cycle increases the maximum
deployment length by a factor of three (alkaline batteries are sufficient for one year). See §1.3 for
a detailed description of sampling strategies and duty cycle calculation.
The Argonaut stores 418 bytes of header information per file and either 33 or 20 bytes for each
velocity sample (based on the setting of the data format parameter). All samples from an
individual deployment are stored in a single file. The Argonaut internal recorder has a 2-MB
capacity and can store up to 62,000 or 100,000 samples. Except where required by data storage
limitations, we suggest using the LONG data format setting (33 bytes per sample).
The Argonaut recorder is divided into 32 blocks of 64 KB each; only one data file can be written
in one block, although one data file can occupy multiple blocks. Thus, the recorder can hold a
maximum of 32 data files. If you record a large number of small data files (less than 64 KB per
file), the recorder will reach maximum capacity before 2 MB of velocity data have been stored.
Be sure to format the recorder to erase all files before any deployment.
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Argonaut Operation Manual Firmware Version 7.9 (May 1, 2001)