Ibex Battery Systems
General Description This bare-board, 2 mode charger is designed to provide low-cost battery charge maintenance for standby power. It has very low reverse leakage and may be permanently connected to the battery. Short-circuit and reverse-battery connections do not damage the unit.
Although this unit will fully charge a battery, because it is a 2 mode charger, it will take much longer than with a 3 mode unit. Please see App. Note 4 for further explanation.
Output temperature-compensation prevents over-charging at high temperatures and under-charging at low temperatures. The unit operates in an ambient temperature of 0C to +40C and carries a one year limited warranty.
The charger 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 the user's front-panel LEDs.
Dual Charging Modes The charger automatically switches between two charging modes, constant-current (fast) mode and constant-voltage (float) mode. Constant-current mode allows a discharged battery to be charged at the highest possible rate. Constant-voltage mode allows a battery to be maintained at full charge without deteriorating from overcharging or undercharging. While in either mode, an external circuit may draw current from the charger (up to the current limit) without disrupting the charging modes.
Constant-Current Mode When powered-up, a charger is in constant-current mode. In this mode, a battery is charged at the maximum current (less any current used by an external circuit). The charger remains in this mode until the battery voltage reaches the mode switching point (approx. 14.7V). At this point, the charger switches to constant-voltage mode.
A unit may be used to power an external circuit while charging a battery. The charger delivers the remaining current to the battery. Because the charger doesn't switch charging-modes based on a tapering-off of battery charging current, the charger can't be tricked into locking-up in fast-charge mode because an external circuit is drawing current.
Constant-Voltage Mode When a charger is in constant-voltage mode, the charger's output voltage is set to the battery's float voltage (approx. 13.8V). When charged at its float voltage, a fully charged battery draws a charging current that matches the battery's internal leakage current, thus keeping the battery fully charged. Maintaining a battery's charge in this way maximizes the battery's service life.
Safety These chargers use U.L. recognized split-bobbin power transformers hi-pot rated at 2500VRMS.