Chapter 3: Using the HOBO U30 Station
HOBO U30 Remote Monitoring System User’s Guide
43
Battery voltage
Details
4.3 to 4.5 volts
The battery is being charged.
4.3 volts
The battery is fully charged.
4.05 volts
Level at which HOBOlink.com will notify you that the
battery is low (if you have enabled a system alarm for
low battery).
3.5 to 3.9 volts
Level at which the HOBO U30 Station will stop trying to
connect to a cellular tower. Logging will continue. When
the battery power returns to above 3.9 volts (e.g. the
sun comes out or the AC adapter has been plugged in),
calls to HOBOlink will resume.
3.0 to 3.6 volts
Level at which the HOBO U30 Station will perform a
safe shutdown. Logging will stop and no calls will be
made to HOBOlink. Use the AC adapter to recharge the
battery (leave it plugged in for twelve hours). Plug the
solar panel back in when you’ve finished recharging
(plug the battery in first if you unplugged it). The system
will resume calls, but you will need to relaunch it using
HOBOlink (select Force Relaunch on Next Connection
in Launch Configuration). You may also want to do a full
readout before relaunching to be sure you have all the
data from the logger.
Approximately
3.0 volts
The battery is too low to safely be charged with the
HOBO U30 Station and may need to be replaced.
Connecting the AC adapter at this point will not
recharge the battery. To recharge the battery, a
separate battery charger will be required. See page 46
for details.
Important:
Do not relaunch the logger until the data
has been recovered. The logger uses very durable,
high-capacity Flash memory. With this memory, data is
retained even when the battery runs out of charge. After
you replace the battery, attempt to read out the data. If
you are still unable to read out the station once the
battery has been replaced, contact the vendor that sold
it to you. It may be possible to retrieve the logged data.
Chapter 3: Using the HOBO U30 Station
44
HOBO U30 Remote Monitoring System User’s Guide
The voltage used in determining behavior in the chart above is based on a
20-minute average. Even though battery voltage is recorded in the data file at
each logging interval and sent to HOBOlink at each connection, the HOBO
U30 Station is operating independently on its own internal 20-minute
average. This ensures that the appropriate action is taking place within the
HOBO U30 Station regardless of how frequently it is logging and
connecting to HOBOlink.
Estimating battery life without external power
The HOBO U30 Remote Monitoring System is designed to be used with a
power source to keep the 4-volt sealed lead-acid battery charged. Ideally, the
power source is always connected and the battery will be constantly trickle-
charged. If external power source has stopped supplying power (e.g. there is
power failure or the solar panel is covered), the HOBO U30 Station is
capable of running from battery power alone for extended periods of time.
The following table can be used as a guideline for estimating how long a
HOBO U30 Station will run without any source of external power. For these
examples, the HOBO U30 Station has up to ten sensors installed and no
excitation on the Analog Sensor Port.
Connection Interval
Logging Interval
Typical Run Time
10 minutes
1 minute
10 days
1 hour
5 minutes
30 days
6 hours
30 minutes
60 days
See the Support section at www.onsetcomp.com for additional information
on estimating battery life and selecting the correct size solar panel.
