Ibex Battery Systems
Mounting The output voltage of the charger is temperature compensated to match the requirements of a sealed lead-acid battery. The charger and battery should be mounted in the same enclosure so they experience the same ambient temperature.
Ambient temperature differences between the charger and battery have little effect during battery charging (bulk mode or absorption mode). If, however, the temperature difference is greater than 10C during float charging, the charger's output voltage may no longer be correct for long-term battery charge maintenance.
The charger is designed to be mounted inside a chassis or equipment rack. There are four press-in standoffs in the bottom of the chassis. These have a minimum of 0.187 inch of available 6-32 threads to be used for mounting. Also, there are eleven 0.201 mounting holes in the side and the bottom of the chassis suitable for #10 hardware.
Because the power transformer constitutes the bulk of the unit's weight, it is preferable to mount the unit using the four mounting holes near the transformer.
The charger dissipates approx. 30 watts under worst-case conditions (high line and low battery voltage). Most of this heat is transferred to the charger's chassis, which acts as a heatsink. Sitting on a bench, the chassis becomes quite warm at full output current.
If the enclosure is metal and the charger is bolted to it, the enclosure acts as an extension of the heatsink and transfers some of the heat to the outside. When using a small, non-metallic enclosure, a small fan may be necessary to keep the enclosure temperature within the 60C maximum. Also, high temperatures drastically shorten battery life.
With a large enclosure and adequate ventilation, a fan should not be needed.
Charger Status Signals The charger has two signals available to power customer-supplied LEDs or interface to TTL/CMOS logic. The "+PWR" (power) signal indicates that the charger is being powered by the AC mains. If the power to the charger is interrupted, the +PWR signal goes off.
The +CHG signal is high during the first two modes of a charge cycle (bulk mode and absorption mode). The +CHG signal is off during the float mode. During a power failure, the +CHG signal flashes a signal to indicate the remaining battery voltage.
The +CHG signal is supplied from a digital 5V source via a 300 ohm resistor and may power standard non-resistor LEDs or TTL/CMOS logic. The +PWR signal is supplied from a DC power source (approx. 12V) via a 1K resistor.
Input Power The charger is designed to be powered from a 115VAC or 230VAC 50/60Hz line. The line input should be externally fused at 1.0A(115VAC) or 0.5A(230VAC). The four power transformer line terminals must be connected as follows. It is important that both primary windings be used. Do not use the charger with just one winding connected.
Charging Cycle When AC power is turned on, the charger will begin a charging cycle (described below). This will occur even if the battery is fully charged. A fully charged battery draws a miniscule charging current and is not be damaged by the charging cycle. The charger never forces current into the battery. It sets an appropriate output voltage and allows the battery to draw whatever current needed for proper recharging.
This charging cycle will last for at least 2 hours. A charging cycle will also be initiated if the charger goes into current limit. This may be because the load has drawn more than the maximum current capability of the charger.
Whenever the current draw of the load exceeds the 1.5A current limit of the charger, the battery must make up the difference. This partially (or completely) drains the battery requiring that a charging cycle be performed when the excess current draw is removed.
Enhanced 3-Mode Charging This 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.
Mode 1 - Bulk Mode: The charger is in current-limit and delivers its maximum rated current (3.0A) to the battery. It is in this mode that the battery receives most of its recharge.When the battery voltage rises to approximately 14.7V, the battery is at a 75% to 90% recharged level and the charger switches to absorption mode.
Mode 2 - Absorption Mode: The charger is in a constant-voltage mode delivering approximately 14.7V to the battery. It is in this mode that the battery is brought to a 100% recharged level.
The charger's microprocessor calculates how long to keep the charger at the elevated absorption mode voltage. It doesn't matter if a load is across the battery during charging. The charger compensates for any current stolen by the load and completely recharges the battery.
Mode 3 - Float Mode: The charger is in constant-voltage mode at a lower voltage than in absorption mode (approx. 13.8V). This allows the battery to draw just enough current to make up for its internal leakage current.
The +CHG signal is low during the float mode.
When the charger is in this mode, the battery may remain connected to the charger for all of the battery's service life with no damage to the battery.
If the battery is removed while being charged, the charger attempts to continue charging the (now-disconnected) battery. It automatically resets itself to the float voltage after an hour or two. If the battery (or a different battery) is connected to the charger during this time, the charger figures things out and re-calibrates its charging times to properly charge whatever battery is connected to it.
Battery Connection Connect the positive battery terminal to the charger's "+BAT" terminal. Connect the negative battery terminal to the charger's "-BAT" terminal.
When off, the charger draws very little leakage current from the battery (<1mA) and so may be permanently connected. The load does not have to be disconnected when charging the battery.
Do not over tighten the terminal screws. The output terminal block is plastic and can be damaged. The proper torque is 50 inch-ounces (0.4Nm).
The charger is not damaged by a short circuit at the battery terminals. However, in the event of a short circuit, even though the charger is not damaged, the battery may deliver a very large current that may melt wires or cause a fire. The battery should be fused close to one of its terminals. polymeric fuses work well. Size the fuse according to the current draw of the application.
The charger is designed to be connected to a battery. Without a battery, a 1000uF/25V (or larger) capacitor is needed across the charger's battery terminals to maintain stability.
LED Connections Connect the anodes (+) of the user-supplied indicator LEDs to the "+CHG" and "+PWR" terminals. Connect the LED cathodes to the battery negative terminal. Use LEDs or LED assemblies that do not have series resistors unless it is desired to reduce the LED current further (approx. 10mA).
Load Connection Connect the optional load to the LOAD terminal. The LOAD terminal is normally connected internally by the charger to the +BAT terminal. The application's load returns to the -BAT terminal.
In the event of a line power failure, the charger maintains the connection of the two terminals while constantly monitoring the battery voltage. If the battery voltage drops to a level that may damage the battery, the charger disconnects the LOAD terminal from the +BAT terminal. When line power is restored, the charger reconnects the LOAD terminal to the +BAT terminal.
It is permissible to connect the load directly across the battery if the charger's battery-disconnect feature is not desired. It is also permissible to use the unit as a stand-alone battery charger with no load connected.
Load Current The load may draw up to 6A (RMS) at room temperature. The charger will supply up-to its maximum output current with the battery supplying the rest. The load current terminal is fused on-board with a polymeric fuse (Raychem RGE600 or equiv) which dictates maximum RMS current at higher temperatures - refer to the fuse specifications
Recommended Battery Size 9.0Ah or larger
Power Failure Operation When the charger's line voltage drops to a level too low for proper battery charging, the charger switches to power-fail mode. The charger will not disconnect the +BAT from the LOAD terminal unless the charger is in power-fail mode and the battery voltage drops to the disconnect level.
In power-fail mode, the charger maintains a connection between the LOAD terminal and the +BAT terminal. The charger also constantly monitors the battery voltage. During this time, the charger can use the +CHG terminal to report the level of the battery voltage by providing a series of on-off pulses. This depends on the value of the optional diagnostic programming resistor used.
The following power-fail signal occurs when the AC mains fail. The values of the pulse widths were chosen to allow easy visual pulse counting when an LED is connected to the CHG terminal.
The first 2000 millisecond pulse signals the start of the pulse train. This is followed by a 500mS off time.
There follows a series of from zero to five 66mS pulses, with a 250mS spacing, followed by a second 500mS off time. The pulse train repeats this pattern continuously. The pulse-width tolerance is +- 5%.
The number of 62mS pulses is determined by the battery voltage.
5 pulses: Voltage = 12.60V and above (approx 80% - 100% charge level).
If the battery voltage drops to 10.80V, a 60 minute timer is started. Should the battery voltage rise above 10.80V during this time, the timer is reset. The voltage must remain below 10.80V continuously for 60 minutes for the battery to be disconnected from the LOAD terminal.
If the battery voltage drops to 10V, the battery is disconnected immediately.
When line power is restored, the charger reconnects the LOAD terminal to the +BAT terminal and restarts a battery charging cycle.
Once the charger disconnects the battery terminal from the load terminal, it will remain disconnected until the AC line power is restored. This is true even if a fully recharged battery is swapped for the discharged one during the power failure.
The charger can, however, be fooled during a power failure (if need be). After swapping a recharged battery for the discharged one, briefly connect a jumper (or perhaps a push button) from the +BAT terminal to the LOAD terminal. This will allow the charger to start operating again in normal power-fail mode.