corresponding to the type label. The month and year of the last calibration are dis-
played (cf. Section 10) along with the memory capacity.
By pressing the ON-OFF button again the VM22 switches itself off. In addition, the
instrument has an automatic shut-off timer for saving the battery power (see cf.
Chapter 4.4).
4.3. Battery Display and Battery Type
In the upper left corner of the VM22 display there is a battery level indicator (6).
When the green battery symbol is full, the battery is fully charged.
While non-rechargeable batteries have a cell voltage of 1.5 V, NiMH rechargeable
batteries deliver only 1.2 V per cell. The VM22 battery indicator can be adjusted to
both voltages. To adjust the voltage remove the sensor from the VMID and press F2
to open the main menu. Here the battery type can be changed by pressing F1 to
scroll down to the menu option 'Instrument Settings' and then pressing OK. Within
the sub-menu select “Battery type” by following the same instructions as before (7)
and then by pressing F1 scroll between F1 “Alkaline” (non-rechargeable, 1.5 V) or
“NiMH Accu” (rechargeable, 1.2 V). Confirm your choice by pressing OK and exit
the menu by pressing F2 repeatedly.
If the power supply drops below 3.3 V when using alkaline batteries or below 3 V
with rechargeable batteries, the battery indicator becomes red. Further measurements
can be taken until the power supply reaches 2.8 V in keeping with the instrument
specifications. At this point the battery level indicator is completely empty and the
instrument switches itself off automatically.
If the VM22 is connected to a USB port, it will be supplied by the USB voltage in
order to spare the batteries. In this case, “External” is displayed on the screen in-
stead of the battery level indicator.
4.4. Shut-off Timer
The VM22 has a shut-off timer to help prolong the battery operating life. To set the
shut-off timer, remove the sensor from the VMID and press F2 to open the main
menu. From the main menu scroll down to the sub-menu option “Instrument Set-
tings” by pressing F1 and OK. Here the menu option “Shut-off timer” can be se-
7
Figure 6: Battery indicator upper left
Figure 7: Select battery type
