Datasheet

This board will be controlled by the Sensor&Management Board which will provide all of the
necessary signals to activate, deactivate or charge each of the batteries. The Power Switch Board
also has the necessary electronics to provide the measure of voltage of each of the batteries. All the
control signals and voltage measurement circuits are completely decoupled by the use of
optocouplers and opto-amplifiers.
Finally this board connects to the Charger Board that will allow the connection and charge of up to 8
batteries.
4.2.3. Charger Board
The Charger Board is used to charge up to 8 batteries independently. Each charging circuit uses a 3-
phase lead acid battery charger already developed, tested and used in IDM’s Projects.
The charger uses the following phases:
1. Bulk Phase. In this charging phase the charger will supply a constant 2A current to the
battery that is charging. This will allow the battery to charge to about 70% of its capability.
2. Absorption Phase. After leaving the Bulk Phase the charger will enter the Absorption Phase
where the charger will supply a constant voltage to the battery until it reaches about 100 to
120% of its capability.
3. Maintaining Phase. When the battery is fully charged the charger will leave the absorption
phase and enter the Maintenance Phase where a 13.4V supply is supplied to the battery until
the battery is disconnected from the charger.
The charging process for the 12V 17-20Ah batteries used in the FROG robot is the following. If the
battery is dried (9.5V - 0%) the battery will start to charge in Bulk Phase for about 7 hours at 2A. At
the end of the 7 hours the level of the battery is about 70%, that means that the charge level will raise
about 10% each hour. After +/- 7 hours the charger will enter into the Absorption Phase where there
will be an increase of about 5% of level of battery each hour. After 5 to 6 hours the battery level will
reach 100%-120% (depending on the type of battery, number of cycles and correct maintenance).
After this period the system will enter into the Maintaining Phase, and the battery will maintain the
charge level.
Figure 11 shows the battery charge characteristics using the developed charger. Only the Bulk and
Absorption Phases are displayed. The Maintaining Phase start can be set to any point of the
Absorption Phase by changing the value of one resistor component.
FROG – FP7 STREP nr. 288235
Deliverable: D1.4 – Platform User and Developer Manual 20
Figure 10: developed Power Switch Board