7. Power supply
current consumption of 8 mA is approx. 230 hours. In sleep mode with a cycle
of 1 minute it should be possible per battery charge to perform measuring ope-
rations for approx. 390 hours. By extending this cycle to e.g. 1 hour, this time
can be increased to approx. 400 days.
Important : The operating time depends very much on the current draw of the
sensor being used.
Charge status indication
The charge status of the rechargeable batteries is indicated by two LED colors
(see 1). The following table lists the LED activity and the associated battery
charge status.
LED activity
Description
OFF
Mains unit not connected
Green
Mains unit connected, batteries fully charged
Red
Mains unit connected, batteries being charged
Important : Critical battery status is indicated by 'LOBAT' in the 2790's display.
(see 7.1.3).
7.1.2 Operation using standard batteries
Alternatively, it can be powered using standard commercially available AA bat-
teries. We recommend using such batteries with a high capacity. Using lithi-
um batteries (e.g. Energizer Ultimate Lithium LR91-FR6) the operating time
can even be doubled.
7.1.3 Supply voltage monitoring
The operating voltage is displayed each time the device is switched on, thus al-
lowing the user to estimate the remaining operating time. In the event of batte-
ry voltage falling below 3.4 V (with rechargeable batteries) or 3.2 V (with stan-
dard batteries), i.e. approx. 10 percent remaining battery capacity, the
LOBAT
arrow will appear in the display. Now, if rechargeable batteries are being
used, the mains unit should be connected in order to recharge them - or, if
standard batteries are being used, these should be replaced. Battery status
can be monitored on the receiving device; this is activated by programming a
measuring channel 'UbAt' on the 2790 within the first four channels transmitted
and a limit value on the destination system. Alarm reporting can also be acti-
vated. To replace used batteries first unscrew the battery compartment cover
(6) on the rear of the device, remove the old batteries, and, observing correct
polarity, insert the new.
7.2 Mains operation
The ALMEMO
®
2790 can be powered from an external source preferably using
mains adapter ZA 1312-NA10 (12 V / 2A) connected at the DC socket (3).
12 ALMEMO
®
2790
