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An alarm system needs to alert the operator to abnormal battery conditions and to aid him or others in the rapid diagnosis of the causes of the abnormal condition.

Charles Industries provides a wide range of alarm components to allow the design of the right system:

Alarm relays are available for AC power failure, low and high DC voltage, and current failure:

  1. The AC power failure alarm indicates no AC supply or a tripped AC circuit breaker.
  2. The low DC voltage alarm indicates no AC supply voltage, input AC breaker has tripped, or the charger has failed.
  3. A high DC voltage alarm indicates battery or load problems.

Low voltage alarms, set to alarm below the charger output voltage but above the open circuit voltage of the battery, duplicate the operation of current failure alarms.  Since current failure alarms are subject to falsing due to the low current drain of fully charged batteries, low voltage alarms are preferred.

An operator needs an operator-friendly system.   Traditionally, green means AC is ON and the system is OK.  Yellow means the system is being equalized.  Red means the system battery voltage is incorrect and needs immediate attention.

If there is no operator in the area, there may be no need for lights on the charger, but there is a need to communicate the alarm conditions.  If the monitoring location is near, a single summary alarm contact may be all that is necessary.  If the monitoring location is distant or difficult to reach, it is desirable to communicate all of the necessary alarms so that the monitoring site can completely diagnose the problem before dispatching service people.  The trip may not be necessary.

Alarm relays require precision adjustments to tailor the alarm system to the battery and the environment.

Compare These Features

Operator Friendly
Green, yellow, red exception system alerts the operator and permits rapid diagnosis of abnormal conditions.

Precision Adjustments
Fifteen turn potentiometers and hysteresis adjustments permit tailoring the alarm system to the battery and the environment.

Heavy Duty SPDT Relays
Rated 10 amps 250 VAC-30VDC.

Local and Remote Capabilities
Summary alarm relay is supplied in Remote Alarm Package.  Separate alarm relays are available to provide complete information from inaccessible sites.

Complete Line
Allows design of right system.

Two Year Limited Warranty.

Alarm Relays

Low Voltage (L)
Battery has been discharged.
No AC supply voltage.
Input breaker has tripped.
Charger has failed.

High Voltage (H)
Battery or load problem.

AC Power Failure (P)
No AC supply voltage.
Tripped AC breaker.

Current Failure (F)
No AC supply voltage.
Input AC breaker has tripped.
Charger has failed.
False alarm -- low current due to fully charged battery.

Remote Alarm Package (R)

Summary alarm (SPDT)
Red LED for high DC voltage.
Red LED for low DC voltage.
Green LED for AC-ON.
Yellow LED for Equalize.

Low and high alarms
have precision adjustments.

Alarm Lights

Neon AC-ON light replaces standard equalize
light. LED for above alarm relays.  Maximum
High DC Voltage
Low DC Voltage
Current Failure


Normal Settings
Low Voltage LA 2.08 2.00
High Voltage LA 2.50 2.40
Remote Alarm Package
Low Voltage LA 2.08 2.00
High Voltage LA 2.40 2.50
Each alarm relay has a terminal board at the top of pc board with three screw lugs for use with 18 GA wire.  Terminal 1 is NC, terminal 2 is common, and terminal 3 is NO.

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