Ibex Battery Systems
General Description: This enhanced 3 mode open-frame charger is microprocessor controlled and features a compact aluminum chassis with threaded inserts for easy mounting. It may be used as a combination charger and power supply and features two available LED signals. One signal indicates that the charger is powered, and a second indicates that the battery is being charged. The signals may be interfaced to TTL circuitry or can power front-panel LEDs.
The output voltage is temperature-compensated to prevent over-charging at high temperatures and under-charging at low temperatures and may be user-adjusted in the field. Conservative ratings and a 105C rated filter capacitor allow a long service life in commercial environments.
Combination Charger/Power Supply This unit is designed to be permanently connected to the battery and the application load. When AC mains power is available, the charger will charge and maintain the battery while also powering the application load. When the mains power fails, the battery continues to power the load with no service interruption. The current draw by the load does not interfere with the operation of the charger.Enhanced 3-Mode Charging: The unit automatically charges the battery in three modes (bulk, absorption, and float charging). Because the charger is controlled by a microprocessor, it has the "intelligence" to determine whether or not a load is connected across the battery as it is being charged and to compute the ideal charging time for each charging mode. Because of this, the charger can be used to charge stand-alone batteries or as a combination charger/power supply. In either application, the charger properly charges the battery, using each of the three charging modes, with no danger of the charger locking itself into the absorption mode ( App note 6, "Why some chargers fry batteries" ).
Mode 1 - Bulk Mode: The charger initially is in current-limit and delivers its maximum rated current (1.0A) to the battery. It is in this mode that the battery receives most of its recharge. When the battery voltage rises to approximately 29.4V, the battery is at a 75% to 90% recharged level and the charger automatically switches to absorption mode.
Mode 2 - Absorption Mode: The charger is now in a constant-voltage mode delivering approximately 29.4V to the battery. The charger's microprocessor calculates how long to keep the charger at the elevated absorption mode voltage. It doesn't matter whether a load is across the battery during charging. The charger completely recharges the battery by altering its charging schedule to compensate for any current stolen by the load. When the charger determines that the battery is 100% recharged, the charger automatically switches to float mode.
Mode 3 - Float Mode: This is for battery charge maintenance. The charger is now in a constant-voltage mode at a lower voltage than in absorption mode (approx. 27.6V). This allows the battery to draw just enough current to make up for its internal leakage current. The battery may remain connected to the charger for all of the battery's service life with no damage to the battery.
The charger remains in float mode, maintaining a 100% state of charge in the battery, until the charger is needed to perform another charging cycle. If this happens, the chargers automatically switches back to bulk mode and the entire 3-mode charging cycle repeats.
Low-Battery Disconnect: A separate terminal is provided for the load. The +battery terminal is connected to the load terminal via a power MOSFET switch. During a line voltage failure, the charger's microprocessor constantly monitors the battery's voltage. When the battery voltage drops to a sufficiently low level, the MOSFET switch disconnects the load terminal from the +battery terminal. The switch automatically reconnects the +battery terminal to the load terminal when line voltage is restored.