Abstract: A refrigeration system alarm device includes a temperature monitoring circuit which detects when a temperature within the refrigeration system exceeds a preselectable temperature reference level. The device also includes an alternating current power monitor circuit which detects when any one of a plurality of alternating current power inputs is interrupted. The device also includes a direct current power monitor circuit which includes a battery and a comparator circuit for determining when the voltage of the battery is below a predetermined level. When an excessive temperature is detected or an alternating current power input interruption is detected or the battery voltage is below the predetermined reference level, a visual or audible alarm signal is generated.