Low Voltage Warning and Aux Battery Management Module

The Low Voltage Warning and Aux Battery Management Module was originally designed by Bob Nuckolls but now has been redesigned, and made into an SMT epoxy-potted module.

The purpose if this device is to monitor the voltage on the essential (or other) bus, signal when the voltage has fallen below a safe value (13V) and switch off the auxiliary battery contactor (thus saving the aux battery for later). When and if the bus voltage returns above 13V the device returns to its normal status.

The device has a blinking LED on board that is in series with a user-supplied panel-mounted LED. This device may be mounted with double-sided tape or bonded to a small attachment plate as desired. A resistor in series with the external LED can be used but is not required. Connection to incandescent lamps is available.


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  Basic Specifications:

Dimensions: 1.03”X1.50”X0.30” (26X38X8mm).
Weight: Less~1/2 ounce (15 g)
Connectors: 0.250” male quick tabs.
Molex 22-23-2021, 2-pin male to Panel LED (supplied)
Low Volt Warning Level 12.70 +/-0.15 Volt
Maximum Voltage Input=18 VDC
Minimum Working Voltage=6 VDC
Power consumed at 18 VDC=50mA, at 12.5 V=12 mA
Max Continuous Current from Aux Battery Contactor Relay Coil=5A
LED Flashing Frequency=~2.5 Hz