Battery Power Supply Operation

The PS12B Battery Power Supply is a companion external “pure DC” power supply for powering Tortuga Audio LDR passive preamps in lieu of their “wall-wart” style external AC power adapter. The PS12B is a battery plus a self-contained battery charger that is powered via AC mains. The PS12B must be connected to AC power and turned on (via a rear panel switch) to operate. The PS12B’s nominal 12 volt power output should be connected to the Tortuga Audio preamp and the PS12B’s 12V Trigger input should also be connected to the preamp’s 12V Trigger output. During normal operation, the PS12B’s charger is connected to the battery and keeps the battery fully charged while providing power to the Tortuga preamp when it’s turned off. When the preamp is turned on, the charger automatically disconnects from the battery. When disconnected from its charger, the PS12B provide filtered, unregulated, “zero ripple” pure DC power free of any AC artifacts. With the preamp turned on and the charger disconnected, the battery will slowly discharge over time. The PS12B has sufficient capacity to run a Tortuga Audio passive preamp continuously for at least 6-8 hours before requiring recharging. When the Tortuga preamp is turned off the battery charger will automatically reconnect to the battery and resume recharging. Any time the battery voltage drops below ~12.1 volts the battery charger will reconnect to the battery even if the preamp is still turned on. If the battery voltage should drop below the safety level of 11.9 volts, the output of the PS12B will shut off completely until the battery is recharged to at least 12.5 volts. You can run the preamp while the battery charger is connected to the battery but the quality of the power supply is degraded from the AC noise that bleeds through the charger’s voltage regulator circuit.

Controls

The PS12B Battery Power Supply is controlled through a combination of the 12V external trigger input from the preamp and also via a pushbutton on the front panel. Assuming the battery is sufficiently charged, either control will disconnect or connect the charger from the battery.

When voltage is applied to the 12V external trigger input, the charger will disconnect from the battery and pure DC power becomes available free from any AC artifacts. Absence of an external trigger voltage will reconnect the battery. Similarly, the front panel pushbutton will toggle the charger connection to the battery. Both control inputs operate by “state change” such that a change in either will override the prior input. For example, even if the preamp is on and the charger is disconnected, subsequenly pressing the front panel pushbutton will reconnect the charger to the battery.

Status Indication (front panel)

Pushbutton/Green LED:

• On – charger connected
• Off – charger disconnected

Status LED:

• Blue – AC power connected and unit turned on
• Red (blinking) – Battery voltage low
• Red (solid) – Battery voltage too low | overrides all control inputs by connecting charger | turns off output from PS12B until battery voltage recovers

Battery Voltage Levels

• 14V – Fully Charged (max) – no load
• 12.1 -13.7V – Normal operating range under load
• <12.1V – Battery low – red LED starts blinking
• <11.9V – Battery too low – red LED solid – power supply output disconnects

Most people are surprised to learn that by the time the voltage in a nominal 12V sealed lead acid (“SLA”) battery drops to 12 volts, it is at least 50% discharged. In fact, repeated discharge below 12 volts will shorten the life of the battery. Similar to an automobile battery, it’s not unusual to charge a 12V SLA battery up to ~14 volts. This is the case as well with the PS12B Power Supply. However, as soon as load is applied to a fully charged battery, its voltage will drop down into the 13 volt range with the voltage dropping down through the 12 volt range as discharge approached 50% at around 12.1 volts.

Specifications

• Battery Type: Two (2) 12 volt sealed lead acid batteries wired in parallel
• Battery Capacity: 3.4 Ah each for a total of 6.8 Ah capacity – fully charged
• Output Current: Optimized for up to 200 ma | 400 ma maximum continuous | output fuse is rated at 0.5 amp
• Output Voltage: Up to 14 volts max – no load – fully charged | 11-13.5 volts normal operating range under load
• Output Quality: Filtered “zero ripple” unregulated battery sourced power while disconnected from charger
• Battery Charger: Current limited (500 ma) smart charger | trickle charge will maintain full charge indefinitely | max ~14 VDC
• Charger Disconnect: Charger disconnected from battery during normal use via front panel push button or 12V trigger input
• Charger Input: 120/240 VAC standard IEC plug mains input | switchable via internal jumpers | 1 Amp fuse
• Power Supply Output: 5 mm barrel jack with 2.1 mm pin
• Trigger Input: 3.5mm mono jack | presence of nominal ~12V input disconnects charger if battery voltage above safe level
• Enclosure:
  • Robust black powder-coated uni-boxy extruded aluminum box
  • 0.1 inch black anodized milled aluminum rear panel
  • 0.25 inch black or silver anodized milled aluminum front panel
  • Four (4) 1 inch square no-slip urethane rubber feet
• Rear Panel:  IEC power entry | barrel jack power output | 12V trigger jack input | power on/off switch
• Front Panel: Charger connect/disconnect push button plus LED status light
• Size (package): Width – 8″ | Length – 12″ | Height – 6″
• Size (unit): Width – 6″ | Depth – 8″ | Height – 3.5″ (with feet)
• Weight (shipped package): ~11 lbs
• Weight (unit): ~10 lbs
• Items Included: Power Supply unit | 18 inch power output cable | 18 inch trigger out cable | 6 foot IEC AC power cable