General Assist Technical Reference
Chiller Unit Battery Pack Charger
NBC24V1BLCWMN - installation, testing and service checks
Battery charger part number: 325739
The NBC24V1BLCWMN is a DIN-rail battery charger used to maintain the 24 V DC backup supply serving electronic expansion-valve and superheat-control equipment. On applicable chiller installations, the kit adds a rechargeable battery and connection harness so the existing battery arrangement is converted from 18 V DC to 24 V DC.
Electrical safety: This procedure includes 230 V AC and stored battery energy. Work must only be completed by suitably qualified personnel. Isolate the unit, prove the supply is de-energised and confirm polarity before making or removing any connection.
1. Overview
The battery charger maintains the backup battery pack and provides continuity of control power during a mains interruption. This is particularly important where the unit uses Danfoss EXD316 or EKE-series superheat drivers, because an inadequate battery supply can result in driver alarms, unstable electronic expansion-valve operation or loss of shutdown protection.
| Item | Specification / purpose |
|---|---|
| Battery charger | NBC24V1BLCWMN, part number 325739 |
| Mains supply | 230 V AC connection shown in the installation instruction. Confirm the charger nameplate before energising. |
| Battery system | 24 V DC lead-acid battery arrangement |
| Typical charger voltage | Approximately 27 V DC while charging or floating. Confirm against the charger label and unit schematic. |
| Typical application | Backup supply for EXD316 and applicable EKE1C / EKE1D superheat-control drivers |
Service priority: Before replacing an EKE or EXD driver, verify the battery-pack voltage, charger output, polarity and wiring integrity. A failed charger or weak battery pack may produce symptoms that appear to be a driver fault.
2. Kit contents
| Quantity | Description | Part number |
|---|---|---|
| 1 | Rechargeable battery | 318653 |
| 1 | Battery charger module | 325739 |
| 1 | Pre-terminated connection wire kit | 325852 |
3. Installation procedure
Step 1 - Isolate and inspect
- Switch off and isolate the unit mains supply.
- Prove the electrical cabinet is de-energised.
- Inspect the existing batteries for swelling, leakage, cracked cases, corrosion or damaged terminals.
- Do not install the kit if any battery is physically damaged or if the battery ratings do not match the approved arrangement.
Step 2 - Mount the charger and additional battery
- Install the NBC24V1BLCWMN charger on the DIN rail inside the electrical cabinet.
- Install and mechanically secure the additional rechargeable battery beside the existing battery pack.
- Maintain access to the battery terminals, charger terminals and driver connections.
Step 3 - Convert the battery arrangement to 24 V DC
- Disconnect the original wiring from the battery pack.
- Install the supplied bridge connection so the battery arrangement is changed from 18 V DC to 24 V DC, as shown in the applicable electrical diagram.
- Observe battery polarity at every connection.
- Confirm the total pack voltage before connecting the charger or control load.
Polarity warning: Reversed battery or charger polarity can immediately damage the charger, superheat driver or connected control electronics.
Step 4 - Connect the charger
- Connect the charger in parallel across the complete battery pack, not across a single battery.
- Connect BAT positive to the positive end of the battery pack.
- Connect BAT negative to the negative end of the battery pack.
- Use the supplied harness and the unit electrical diagram to confirm the load and battery connections.
Step 5 - Connect the driver harness
- Connect the female Faston terminals to the battery series connection as shown in the approved wiring arrangement.
- Connect the male Faston terminals from the supplied harness to the female connections already associated with the EXD316 driver circuit.
- Confirm every terminal is fully engaged, insulated and mechanically secure.
Step 6 - Connect the mains supply
- Connect the charger to the approved 230 V AC supply shown in the unit electrical diagram.
- Confirm the correct line and neutral terminals on the charger.
- Do not energise until all DC polarity and AC wiring checks are complete.
4. Commissioning and verification
| Check | Expected result |
|---|---|
| Battery-pack polarity | Correct positive and negative orientation throughout the series arrangement |
| Battery-pack voltage before load connection | Approximately 24 V DC and not below the approved minimum for the connected driver |
| Charger output | Stable DC charging voltage, typically near 27 V DC. Confirm against charger nameplate and schematic. |
| Charger indicators | Power and battery indicators display the normal condition described on the device label |
| Driver supply | Correct 24 V DC supply available at the EXD/EKE control circuit |
| Harness condition | No loose Fastons, exposed conductors, heat damage or incorrect bridging |
A battery-pack reading below approximately 21 V DC indicates a severely discharged or defective 24 V arrangement. Do not reconnect sensitive control electronics until the batteries and charger have been assessed and the voltage has recovered to the approved range.
5. Diagnostic guide
| Symptom | Checks | Action |
|---|---|---|
| EKE/EXD driver alarm or resets | Measure battery-pack and charger voltage under load | Repair charger wiring or replace weak batteries before replacing the driver |
| No charging voltage | Check 230 V AC input, protection devices and charger terminals | Restore supply or replace charger after confirming wiring is correct |
| Battery voltage falls rapidly | Isolate load and test each battery individually | Replace defective batteries with approved matching units |
| Charger or wiring overheats | Check polarity, short circuits, terminal tightness and battery condition | Isolate immediately and rectify before re-energising |
| Correct voltage at charger but not at driver | Inspect Faston terminals, bridge harness and continuity | Repair or replace the connection harness |
6. Service notes
- Use only approved batteries, charger modules and connection harnesses.
- Do not mix batteries of different capacities, technologies, ages or condition in the same series arrangement.
- Confirm the latest unit electrical schematic before changing any battery or charger wiring.
- Record battery voltages, charger output, part numbers and corrective action in the service report.
- After commissioning, confirm the EXD/EKE drivers are powered and free from battery-related alarms.
Need further technical assistance?
Contact General Assist and provide the unit model, serial number, battery readings, charger output and any active controller fault codes.
Australia: 1300 364 484