General: This unit is an uninterruptible power source (UPS) designed to keep a 12V application running in the event of a power failure. The UPS is designed to be powered by automotive, truck, or aircraft battery systems or by solar panels. Any voltage from 10.8V to 32VDC can be used. Whenever a suitable supply voltage is available (10.8V - 32VDC), the UPS directs this voltage to its output pin and on to the user's application. Also, at the same time, the charger built into the UPS draws an additional 1A or so from the supply source to recharge the unit's internal 12V 5Ah SLA battery. Once the internal battery has been recharged, this additional current drops to a low level. If the supply voltage is removed from the UPS, the unit quickly switches its internal battery to the output pin. When the supply voltage is restored, the unit's internal charger recharges its battery. The unit has an internal battery-disconnect feature. This prevents an application from over-discharging the battery below 10.8V (which could damage it). This also allows the UPS to be disconnected from its mating connector and put into storage without the unit's circuitry prematurely discharging its battery. If the UPS is supplying battery power to the load, and the voltage drops below 10.8V, the battery is disconnected and the UPS shuts down. When the Input Supply is restored, the UPS restarts and reconnects the battery. Mounting: Use #10 hardware on all 4 mounting holes. The unit is heavy for its size. Using smaller hardware risks breaking the mounting flanges if the unit is exposed to severe vibration or impact. The unit may be mounted in any position and must be protected from the weather. Thermal Considerations: The unit normally operates in an ambient temperature of -40C to +60C. This is limited by the battery's requirements. The unit's circuits operate normally up to +85C. The unit's charger stops operating above +65C but automatically restarts when the temperature drops below this number. However, above +60C, the life of all SLA (sealed lead-acid) batteries is severely reduced. For the sake of battery life, mount the unit away from heat sources or direct sunlight. Mating Connector: The unit is shipped with an unwired 7 pin mating connector. #22(0.65mm) stranded wire is recommended for application where the distance between the UPS and the load is short. For longer distances, #20(0.81mm) or even #18(1.02mm) wire may be required. The following
#20 is .020V/Amp/Foot
#18 is .013V/Amp/Foot
To arrive at the total voltage drop, make two calculations: 1: Multiply the appropriate number in the previous paragraph by the load current (in Amps) times the cable length between the PCB and load (in Feet).
2: Similarly, repeat the calculation for the distance between the PCB and the power source. This voltage drop is for the total round trip the load current makes - from the PCB and back via the return wire. The total voltage drop when there is an active power source is 1. + 2.
The total voltage drop when the UPS is just running on the battery is 1. To arrive at the total voltage drop, make three calculations: As an example, using #22 wire to power a load that draws 1.5A and is 4 feet from the UPS, the total voltage drop is
Block Diagram Operation Manual Electrical Specs. Mechanical Info.
Pin 1 - Output Power: This is the (+) output of the UPS which is used to power the application load.
If the Input Supply (on Pin 6) is greater than 10.8V, an internal switch connects Pin 6 to Pin 1.
If the Input Supply is less than 10.8V, the internal switch instead connects the UPS battery (12V 5Ah)
to Pin 1.
The unit's transfer from the Input Supply to internal battery takes less than 1 millisecond.
During this time, an internal capacitor connected to the Output Power pin prevents the voltage from dropping to zero during the transfer time.
With a 3A load, the voltage sag at the Output Power pin is approximately 2V during the transfer time.
If the application cannot tolerate this voltage sag, then a sufficiently large capacitor should
be added to the application's power input to hold up the voltage for this period.
Even when the Input Supply drops below 10.8V, the unit's charger can still operate (down to approximately 5V Input Supply) and
can contribute a reduced current to the Output Power pin.
If the load is substantial, then the battery supplies most of the output current and eventually becomes discharged.
However, if the load current is small (less than 0.25A), then the charger is able to provide this output current
and also maintain the battery at 100% charge level.
Because of this, a small solar panel in dim light may be able to keep the battery maintained at 100% charge level if the load current is small.
The application load may draw up to 3.0A steady-state - whether from the Input Supply or the internal battery.
Drawing more than 3.0A continuously may damage the unit.
However, large surge currents (up to 25A for 10mSec) may be drawn on a low duty cycle basis.
A circuit breaker on the Output Power pin has a 1 second delay and trips at between 3.5A and 7.0A.
If the circuit breaker trips, power to the Output Power pin is interrupted.
Once tripped, the circuit breaker can only be reset by briefly disconnecting the mating connector.
Pin 2 - Signal P (Power): This pin supplies a signal to power a standard LED and is internally resistor current-limited.
When the Input Supply (Pin 6) is above 10.8V, this signal is active at 5V.
When the Input Supply is below 10.8V, this signal is zero.
There is about 0.4V of Input Supply hysteresis between on and off for this signal.
This signal is driven from the output of an LM224 op-amp in series with 200 ohms.
The LM224 can source approximately 15mA or sink 1ma.
If driving a TTL circuit and more pull-down is needed, a 270 ohm resistor from this pin to the Common Negative pin helps somewhat.
Pin 3 - Common Negative: This is the negative return for the Input Supply, Output Power, and Indicator Signals.
Pin 4 - Signal F (Fault): This pin supplies a signal to power a standard LED and is internally resistor current-limited.
Unlike the other two Indicator Signals, this signal originates from a 12V source in series with a 2.4K resistor.
This pin has no pull-down capabilities and needs a user-supplied buffer circuit if interfacing with TTL.
If a standard LED is connected to this pin, the LED remains lighted whenever the Output Power (Pin 1) circuit breaker has tripped.
If a LED is not connected to this pin, Indicator C (Pin 5) is used to signal a fault.
Pin 5 - Signal C: (Charge) This pin supplies a signal to power a standard LED and is internally resistor current-limited.
This signal is driven from the output of an LM224 op-amp in series with 200 ohms.
The LM224 can source approximately 15mA or sink 1ma.
If driving a TTL circuit and more pull-down is needed, a 270 ohm resistor from this pin to the Common Negative pin helps somewhat.
When the Input Supply (Pin 1) is above 10.8V, this signal is high whenever the internal battery is bein charged.
When the battery is fully recharged, this signal goes off.
If the Input Supply is below 10.8V, this signal has a different purpose.
While the Input Supply is below 10.8V and the battery is supplying current to the Output Power pin,
the unit's microprocessor monitors the battery's voltage.
The signal on this pin indicates the battery voltage level with a series of flashes.
There follows a series of from one to five 62mS 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)
4 pulses: Voltage = 12.15V to 12.60V (60% - 80%)
3 pulses: Voltage = 11.70V to 12.15V (40% - 60%)
2 pulses: Voltage = 11.25V to 11.70V (20% - 40%)
1 pulse : Voltage = 10.80V to 11.25V (00% - 20%)
If the Output Power circuit breaker trips, the Signal F pin goes high signaling a fault condition. If there is no standard LED connected to the Signal F pin, the Signal C pin is instead used to indicate the fault condition. It does this with a rapid series of flashes. This continues until the unit's mating connector is removed.
Pin 6 - Input Supply: This is the (+) input power source for the UPS. To keep the unit's internal battery from powering the output, the voltage at this pin must be between 10.8V and 32VDC. While the voltage is at this level, the Output Power (Pin 1) is entirely sourced by this Input Supply pin. Also, the Input Supply operates the unit's internal charger to recharge/maintain the unit's 12V 5Ah battery. If the Input Supply voltage drops below 10.8V, then the unit disconnects the Input Supply pin from the Output Power pin and instead connects the internal battery to the Output Power pin. Even if the Input Supply is no longer feeding the Output Power pin, as long as it remains above 6V, the charger still operates - although at a much lower current level. If the current drawn from the Output Power pin is low enough, the battery can still be recharged/maintained with this low Input Supply voltage. However, if the Output Power pin current is above the now-limited capability of the charger, the battery still eventually becomes discharged. Pin 7 - Enable: This pin is normally connected to the Common Negative pin via the unit's mating connector. Grounding this pin allows the unit's battery to be connected to the rest of the unit's circuitry. Do not use this pin for any other purpose. If the unit is to be stored and out of active service, disconnecting the mating connector automatically removes the ground connection for this pin. This causes the UPS to completely shut down and isolates the battery from any circuitry. This prevents the battery from prematurely discharging while in storage. All batteries have internal leakage which increases with temperature. Thus, even disconnected from circuitry, the battery eventually discharges. This can be from one month to a year - again depending on temperature. For this reason, each unit should be connected to a power source periodically. Assuming the battery is charged, re-connecting the mating connector re-starts the UPS. This is done with a small capacitor injecting a startup current into the UPS circuitry. If reconnecting the mating connector is fumbled a bit by the operator, the capacitor may need time to discharge again in preparation for another try. This very seldom happens but, if needed, disconnect the mating connector, wait 15 seconds, and try again. If there is a voltage on the Input Supply terminal, this startup circuit not used and the preceding instructions can be ignored. Battery Replacement: The life of the battery depends on the number of discharge/charge cycles, the depth of discharge, and the ambient temperature. If the input power to the UPS never fails, the battery never undergoes a discharge/charge cycle. Under this condition, the battery can last 5 years or more. If however the battery is subjected to full discharges and recharges, its life is approximately 200 cycles. These numbers are valid for room temperatures only. If the battery is subjected to high ambient temperatures, its life is drastically shortened. To replace the battery, disconnect the mating connector and remove the top cover. Unsolder the red and black wires connected to the battery. The battery slides out if the unit is tipped over on a bench and shaken gently. Replace with a new battery and solder the two wires to the battery (red+ and black-). The replacement battery is a PowerSonic PS-1250F1 or equivalent. This is a standard size battery and many other manufacturers can be found by internet searching.