Loading... Please wait...

APO3: Automatic Power Off 3 (bare wire leads)

1.00 LBS
Calculated at checkout

Product Description

APO3: Automatic Power Off 3

Voltage controlled relay protects vehicle batteries from being discharged by radios.

The APO3 is a black box designed to prevent a vehicle battery from being discharged and damaged by a DC load. Typically it is used to switch a radio transceiver off 10 minutes after the vehicle is shut off.

The APO3 is designed for 12 volt vehicle electrical systems with negative ground. It can switch up to 20 amps and carry up to 30 amps. The shutdown voltage can be set to one of four pre-programmed voltages (11.8, 12.1, 12.7, 13.05 volts) using two DIP switches; the shutdown delay can be set to one of four pre-programmed times (0, 5, 10, 20 minutes). The device is housed in a sturdy ABS plastic case.

Technical Specifications

Dimensions: 84 mm x 121 mm x 34 mm (3.3 in x 4.75 in x 1.35 in)

Weight: 5.5 oz (158 g) with Anderson connectors

Input Voltage: 7-20 volts DC

Input Current:

  • 1.734 mA @ 12.0 VDC with LED off and relay off
  • 60 mA @ 13.8 VDC with LED off and relay on
  • 61.25mA @ 12.7 VDC with LED on and relay on

Load Current: 30 amps holding, 20 amps switching

Internal Protection: Thermal, over current

Case Material: Flame retardant ABS plastic, UL's best flame rating of 94-5VA (case only)

Voltage Set Points: 11.8, 12.1, 12.7, 13.05 volts DC, selectable by DIP switch

Time Delays: 0, 5, 10, 20 minutes, selectable by DIP switch


What it Does and How it Works

The APO3 is basically a voltage controlled switch. When the vehicle voltage is higher than the APO3 set point, the relay is turned on and power is provided to the load side. When the voltage drops below the APO3 voltage set point and stays there for longer than the time set point, the APO3 relay turns off and power is removed from the load side.

The APO3 has a bright yellow LED to indicate its status and it has a slide switch that can be used to turn the load on regardless of the input voltage.

Using the factory default settings, the APO3 will turn on the load when the vehicle voltage rises above 13.05 volts. This typically occurs within a few seconds of starting the vehicle. The load remains powered as long as the engine is running. When the engine is shut off, the vehicle voltage sinks below 13.05. The APO3 waits until the voltage has been less than 13.05 volts for 10 minutes and then turns the load off.

The APO3 is ideal for use with mobile APRS / AVL stations. It allows the radio to transmit a few position reports after the vehicle is shut off before turning off the radio and GPS. This reduces clutter on the APRS / AVL channel and prevents the vehicle battery from discharging.


The APO3 is installed between the vehicle battery and the DC load. Typically, the load is a mobile radio transceiver and accessories. Standard installation involves cutting the DC feed to the radio and using butt splice connectors to install the APO3. This usually takes 10 minutes or less. If you use Anderson Power Pole connectors, we offer an APO3 with Power Poles already installed; this makes installation a literal snap. If you want to change the factory set points, you will need to remove the cover and flip a couple of small switches.


rohs_check_53.png     made-in-USA.53.gif



Find Similar Products by Category

You Recently Viewed...