
IDP 800 Terminal Series - Hardware Guide
© SkyWave Proprietary 27 T209, Version 01
Forced Charger Duration
Low Internal battery voltage
The table below lists the parameters for initiating the charger
Table 19
Charger Initiation Parameters
Parameter
Condition
Min. Typical Max.
Units
Minimum external
voltage for charging
Minimum voltage required
9
-
32
V
Forced update time
Default is the minimum
value. Timer resets after
each charge cycle.
20
20
120
days
Temperature to start
charging
As measured in the battery
compartment
-10
-
45
°C
Internal battery voltage
Charger starts if in correct
temperature range
-
-
12
V
3.8.4.2 Temperature Monitoring
The battery manufacturer specifies a cell voltage range for charging. The IDP-800
charger uses a temperature sensor in the battery compartment to determine the battery
cell temperature. The battery temperature sensor is only available with rechargeable
models. This temperature reading is very different from the modem temperature.
Specifications for the battery temperature sensor are given in the table below
Table 20
Battery Temperature Specifications
Parameter
Value
Range
-55 to +130°C
Accuracy
±2.5°C max (30°C)
±3.5 to ±3.8°C max (-55°C and 130°C)
At any time during charging, if the battery compartment temperature is out of range, the
battery charging cycle is aborted regardless of how much charge is on the battery. If the
battery charging is aborted, it does not restart until the next normal charging cycle.
3.8.5 Charging Stages
A NiMH charger uses three charging current stages to charge the battery. These current
profiles depend on temperature, battery voltage and battery charge status. The current
stages are pre-charge, fast-charge and top-off charge.
Pre-charge current is the first charging stage. It is used while the NiMH battery
voltage is below 12 V. NiMH batteries require a pre-charge stage as they can be
damaged if fast charge is applied when the battery is discharged. Once the battery
voltage exceeds 12 V, the charger goes to fast-charge if voltage range is valid for
this profile. Otherwise, the charger remains in the pre-charge current until the
battery is charged.
Fast-charge current is second charging stage. The charger enters this stage once
the battery voltage is over 12 V. The charger remains in the fast-charge stage for
4 hours or until the dV/dT threshold is exceeded.