This is a charger/controller PCB similar to the one used in the S12UPS-3.0/12DC unit - except with component changes for 24V operation. Connecting this PCB to a user-supplied (3Ah minimum) SLA battery creates a complete UPS. By using a larger battery, the UPS discharge time is greater during an input power failure. It's designed to be powered by a DC source from an automotive, truck, or aircraft battery system, or a solar panel and operates at ambient temperatures from -40C to +65C. The charge circuit stops operating above +65C and automatically restarts when the temperature falls below +65C.
When the PCB is connected to an appropriate DC source (21.6V to 32VDC), the source is connected directly to the output port of the PCB - and, presumably, to the application load. The application load may draw up to 3.0A - all of which is supplied by the DC input source.
While DC input power is supplying the PCB, an internal enhanced 3-mode battery charger recharges and maintains an external, user-supplied, 24V 3Ah (or larger) SLA battery. This charger is a switch mode, buck/boost type which supplies the proper battery charging voltage over the complete DC input voltage range.
If the DC input power is disconnected from the PCB, the external battery is connected to the PCB output in less than a millisecond. The application load may still draw up to 3.0A. However, since this current is now supplied by the external battery, there is a time limit before the battery becomes discharged.
The battery's voltage is monitored by the unit's microprocessor. To protect the battery, if its voltage falls below 21.6V, the battery is disconnected from the output and the PCB completely shuts down. When DC input power is restored to the PCB, the PCB reconnects the DC input power to the PCB output port and starts to recharge the external battery.
There are three signals available to power standard LEDs to indicate the PCB's status. The C (charge) signal indicates that the battery is being recharged. The P (power) signal indicates that the DC input power is above 21.6V and is connected to the PCB output port. The F (fault) signal indicates that the PCB output port has experienced a gross overload - possibly from a short circuit in the application load.
An Enable terminal on the PCB connector is normally grounded by the application.
If the Enable terminal is disconnected from ground (and the supply voltage is less than 21.6V), an internal switch disconnects the external battery
so the unit can be stored long-term without the PCB internal circuitry discharging the battery.
Block Diagram Operation Manual Electrical Specs. Mechanical Info. Price: $91 (1-4)