User's Guide

Development Kit User Guide – Rev11.0
40
About the Battery Charging Process
WiBotic Onboard Chargers are configured by default to act as Constant Current/
Constant Voltage (CC/CV) battery chargers.
If the Transmitter is physically powered, the Transmitter toggle switch is turned on, and
an Onboard Charger is in range, the system will begin charging if the battery is not
already considered fully charged. The charger regulates output voltage to the battery at
the pre-defined voltage limit in the “Battery Settings” menu. The initial voltage limit is set
at the WiBotic factory based upon the customer’s reported battery specs and is listed on
the Certificate of Conformance. The voltage limit can be changed and will be stored in
memory even if the Onboard Charger is powered off and/or disconnected from the
battery.
During startup, the charging current will ramp up to the maximum constant-current
charge rate as configured in the WiBotic software. The Onboard Charger will always try
to ramp-up to the maximum charge current. However, in some cases, depending on
either sub-optimal coil position, environmental conditions or high temperatures of the
electronics, the Onboard Charger may not be able to achieve the maximum charge
current. If unable to reach the maximum charge current, the Onboard Charger will not
increase beyond a charge current that the system can reliably and safely sustain.
After the constant current (CC) portion of the charge cycle is complete, the Onboard
Charger will enter constant-voltage (CV) charging mode. During CV mode, the charge
current decreases gradually as the voltage of the battery approaches the charge
termination voltage.
There are two ways for the system to terminate charging once it is in constant-voltage
mode:
1. CV Mode Timeout: Once CV Mode has started, the Maximum Top-Off Charge
Time period begins. Even if the battery is not fully charged at the end of this
period, the charge cycle will terminate and the Power Transmitter will
momentarily return to standby. If the system senses battery voltage is below the
fully charged level, the system will resume charging until the battery is fully
charged and charger enters CV Mode.
2. CV Mode C/10 “Charge Complete”: If the charge current drops below one-tenth
of the maximum charge current rate (C/10), then charging is considered
complete and the Power Transmitter will return to standby.