Ibex Battery Systems

Diagnostic Testing

Battery Diagnostic Testing This is automatically performed periodically and can be disabled if desired. During the diagnostic test, the charger powers down and allows battery-only power to the application's load. The duration of this test is field programmable by connecting a specific value resistor (1/4W 5%) across the +CHG and -BAT output terminals.

Battery Diagnostic Programming Resistor

The unit's microprocessor constantly monitors the battery voltage during this test. For the duration of the test, if the battery voltage stays above 11.7V, the test is considered to be a pass. If the battery voltage reaches 11.7V, the diagnostic test is terminated immediately, the charger powers back up, and the test is considered to be a fail.

During this test, the voltage to the application's load is never allowed to go below 11.7V. This is to assure continued operation of the load.

After the test completes (either pass or fail), the charger initiates a battery charge cycle. A diagnostic test failure is indicated via the signal at the +CHG output terminal.

The diagnostic test is not performed during a power failure.

Volume users can order units with custom firmware which eliminates the need for the programming resistor. Of course, the user will then be locked-in to a specific diagnostic test and +CHG terminal behavior. There is no extra cost providing the minimum order is 25 pieces.

+CHG Terminal Signals The +CHG terminal is used to signal several charger conditions. Connecting a standard LED or CMOS logic to the +CHG and -BAT terminals is permitted and causes no cross-interaction with the optional programming resistor.

Programmed for Normal +CHG Terminal Signaling This +CHG signaling option is useful if an operator is on-site. LEDs can be connected to the +CHG and +PWR terminals to give a visual indication of the charger's operation. For remote sites with a data link, the alternate +CHG behavior may be more useful.

If the charger is powered by the AC mains (+PWR terminal high), the +CHG terminal is high while the charger is in bulk or absorption charging modes. +CHG is low when the charger is in float mode.

If the AC mains have failed (+PWR terminal low), a signal appears at the +CHG terminal indicating the battery voltage. The Operation Manual details the meaning of the signal sequence.

3 stage sla battery charger

While the charger is performing a diagnostic test, the +CHG terminal remains high with a periodic .066 second blink (+CHG low).

3 stage lead acid battery charger

If the diagnostic test fails, the +CHG terminal continuously alternates .066 seconds high, .066 seconds low. This alternating flashing continues until AC power is toggled off-on.

If the AC power fails at this point, the +CHG terminal stops flashing and reverts to the battery voltage signal (shown above). When AC power is restored, the charger is reset to its normal pre-diagnostic state.

Programmed for Alternate +CHG Terminal Signaling The +CHG terminal gives a go/no-go indication of the battery condition.

If the +PWR terminal is high, the +CHG terminal stays high during all of the charging modes (bulk, absorption, float). This indicates that the load is receiving power.

If AC power fails (+PWR low), the +CHG terminal stays high while the battery voltage is above 11.7V. This is approximately the 50% battery discharge point. When the battery becomes discharged to 11.7V, the +CHG terminal goes low. If this signal is remotely monitored by a data link, it can alert an operator to visit the site before the battery is fully discharged and the load is no longer powered.

If a diagnostic test is run, the +CHG signal remains high during the test but goes low if the test fails - and remains low until AC power is toggled off-on. When AC power is restored, the charger is reset to its normal pre-diagnostic state.

Diagnostic Schedule When the charger is first powered up by the AC mains, the unit performs a complete charging cycle. This is followed by the diagnostic test (if enabled). After completion of the test, the unit performs a second charge cycle. In addition, this sequence (charge, test, charge) is performed every 26 days of uninterrupted power-on operation. A power fail resets the 26 day timer.

The following table shows the various diagnostic test times that are available by connecting a programming resistor from the +CHG terminal to the -BAT terminal. Besides selecting a specific diagnostic test time, the programming resistor also selects one of two +CHG terminal behaviors.

The value of this resistor is only read upon power-up. The battery must be disconnected when installing/changing this resistor.

Diagnostic Test Time Programming Resistor
Normal +CHG Terminal
Programming Resistor
Alternate +CHG Terminal
4 Minutes 1.0K 2.0K
1 Hour 3.0K 3.9K
4 Hours 5.1K 6.2K
12 Hours 6.8K 8.2K
24 Hours 9.1K 10K
36 Hours 11K 12K
72 Hours 13K 15K


Using a 16K programming resistor disables the diagnostic test and causes the charger to adjust its output characteristics to suite a flooded (automotive style) battery (with normal +CHG behavior).

Short circuiting the +CHG terminal disables the diagnostic test.

Using an 18K programming resistor disables the diagnostic test and selects the alternate +CHG terminal behavior.

Removing the programming resistor disables the diagnostic test and selects the normal +CHG behavior.

Connecting a low impedance load to the +CHG terminal causes unpredictable results. At power-up, the charger passes a small current through the resistor to measure it. A low impedance load on the +CHG terminal diverts this current.

Connecting a standard LED in parallel with the programming resistor does not affect the diagnostic test - neither does CMOS logic. An LED doesn't draw current below 1.6V - the maximum resistor voltage is 0.8V (for 18K, when measured at power-up).

Connecting TTL logic to the +CHG terminal injects extra current into the terminal and causes the diagnostic to not be performed.