Juniper Allegro CE Owner's Manual page 35

Battery Life
Depending on the application, the batteries can last from five to 30
hours between charges (NiMH) or replacement (alkaline cells) as
shown below:
Battery Pack
NiMH
Alkaline
The operating times stated above are based on a typical application
including: the data are being entered manually on the keyboard, no
external devices are powered by the Allegro, the backlight is used
10% of the time, and processing time is 20%. The actual operating
time could vary from as little as five hours to as much as 30 hours,
depending on the program and how the system is set up.
Recharging the NiMH Battery Pack
For applications where the Allegro is used for several hours each day,
the NiMH batteries can be charged daily. The Allegro's built-in
intelligent charging circuit manages the charging of the batteries and
prevents them from being overcharged.
You should always be aware of the status of the main batteries before
you go out into the field to collect data. The batteries may need to be
recharged before you go. You need to take into account how much
battery life is left and the amount of time required to charge the pack.
Temperature Ranges for Charging the NiMH Battery Pack
The Allegro's NiMH batteries are charged most efficiently at
temperatures ranging between 10° to 20° C (50° to 68° F) when the AC
power adapter is used.
The Allegro batteries must be charged when the battery temperature is
between 0° to 40° C (32° to 104° degrees F) due to the nature of NiMH
batteries.
Capacity
3,800 mA hours
1,600 mA hours
Typical Operating Time
12 to 20 hours
5 to 10 hours
Hardware Features Page 2-23