Nickel-Cadmium (NiCd) batteries remain a trusted choice in industrial and DC rectifier applications for their robustness and long service life. Yet, these systems present recurring operational challenges when not properly monitored—ranging from electrolyte loss and temperature rise to ground faults and ripple effects that shorten battery life and compromise safety. This whitepaper outlines the most common pain points observed in NiCd battery installations and presents how an intelligent monitoring approach can mitigate these issues effectively.
1. Incorrect Float Voltage Setting
NiCd batteries require a precise float voltage range, typically 1.40 - 1.47V per cell. If the voltage is set too high, the cells remain in a continuous overcharge state, leading to excessive water loss, electrolyte dry-out, and increased maintenance needs. If too low, the batteries remain undercharged, resulting in crystal formation (memory effect) and capacity reduction.
Maintaining the proper float setting is critical for long-term performance.
2. Excessive Cell or Ambient Temperature
NiCd batteries operate reliably between 0°C and 40°C, but sustained temperatures above 35°C accelerate electrolyte evaporation and internal pressure buildup. High temperatures shorten service life, increase water consumption, and may lead to thermal instability. Temperature imbalance between strings or racks can cause unequal charging and uneven cell aging.
3. Low Electrolyte Level
NiCd batteries use an alkaline potassium hydroxide (KOH) electrolyte, which remains chemically stable during operation, but water gradually evaporates.
When the electrolyte level drops below the minimum mark, plates may be partially exposed to air, resulting in heat generation, capacity loss, and possible venting during charge cycles.
Only distilled water should be added, never additional electrolyte.
4. Cell Leakage
Each cell terminal (+/–) is equipped with a high-sensitivity leakage sensor to detect micro-insulation leakage caused by surface humidity or electrolyte residue. Measurement helps identify early degradation before a ground fault occurs.
5. Ripple Current
Ripple current refers to the AC component present on the DC output of rectifiers or chargers. NiCd cells tolerate ripple better than lead-acid types, but excessive increases cell temperature and water consumption.
Prolonged exposure to high ripple reduces electrolyte life and can cause uneven charging across cells.
6. Ground Fault
A ground fault occurs when either the positive or negative pole of a DC systemz becomes unintentionally connected to earth through moisture, contamination, or insulation degradation. Such conditions can lead to current leakage, shock hazards, and, if both poles are affected, short-circuit conditions.
By continuously comparing the insulation condition of the positive and negative sides, a protection relay can detect any imbalance and issue an alarm when a deviation is observed.
This early detection helps prevent equipment damage and improves system safety.
7. Hydrogen Gas Generation
During charging, NiCd batteries emit oxygen and hydrogen gas.
Poor ventilation in the battery room may cause hydrogen accumulation, creating an explosion risk once concentrations exceed 4% by volume.
Persistent overcharging or incorrect float voltage settings further increase gas generation. Proper room ventilation and hydrogen detection sensors are recommended to ensure safe operation.
8. Improper Maintenance Practices
NiCd batteries differ fundamentally from lead-acid systems. Parameters such as electrolyte gravity are not meaningful indicators of charge level or health. Incorrect practices like over-boost charging or improper electrolyte refilling can damage the cells. Routine maintenance should focus on voltage, temperature, electrolyte level, and general visual inspection according to the manufacturer’s service guidelines.
Understanding these technical challenges provides the foundation for designing a reliable and preventive monitoring framework. Addressing each risk with accurate, real-time data allows operators to transform NiCd maintenance from reactive to predictive—ensuring continuity, safety, and compliance across demanding industrial environments.
NiCd Battery Monitoring System Solution by Alpais BMS
The Alpais Battery Monitoring System (BMS) is designed specifically to address the operational and safety concerns of NiCd and industrial DC battery systems. By combining advanced measurement hardware with configurable software thresholds, Alpais BMS delivers real-time visibility into every critical battery parameter, empowering maintenance teams to take timely corrective action and prevent system downtime.
1. Incorrect Float Voltage Setting
Alpais BMS monitors float charge, charge, discharge, and idle positions with editable limits, and generates alarms and sends notifications to the registered users to maintain the NiCd battery rack.
2. Excessive Cell or Ambient Temperature
Alpais BMS monitors cell temperature and ambient temperature separately, and generates alarms and sends notifications to the registered users to maintain the NiCd battery rack.
3. Low Electrolyte Level
Alpais BMS monitors the electrolyte level of each cell, and when it drops to a certain level, the system generates alarms and sends notifications to the registered users to maintain the NiCd battery rack.
4. Cell Leakage
Alpais BMS measures small current leakage from each cell terminal, allowing early detection of electrolyte residue or surface conductivity.
5. Ripple Current
Alpais BMS monitors the ripple current string, and when it detects a ripple in the system, it generates alarms and sends notifications to the registered users to maintain the NiCd battery rack.
6. Ground Fault
Alpais BMS monitors the ground fault (earth fault) of each string, and when there is a fault, the system generates alarms and sends notifications to the registered users to maintain the NiCd battery rack.
7. Hydrogen Gas Generation
Alpais BMS monitors the hydrogen gas in the battery room, and when the gas volume reaches a certain limit, the system generates alarms and sends notifications to the registered users to maintain the NiCd battery rack.
8. Improper Maintenance Practices
Alpais BMS is designed for nickel battery applications. It monitors the cell, string, and ambient parameters and generates alarms to allow the users to take action before any downtime and risk to the area.
9. Extra: Extended Capacity for Industrial Batteries: Up to 480 cells monitoring with Alpais BMS
In industrial areas, high-voltage battery packs, consisting of more than 120 cells in one serial connection (string), are chosen. Some of the data center applications the UPS require 480 DCV, and most NiCd applications consist of more than 100 cells in one string. This is a pain point for battery monitoring systems in the market.
With the brilliant and flexible Alpais Software design, Alpais BMS can monitor up to 480 cells on 1 string.
As seen in the above configuration, the user can monitor the batteries as 1 string, as it should be, without any complexity for the users. Through its modular design, multi-protocol communication, and precise measurement capability, Alpais BMS provides an all-in-one diagnostic and protection platform for NiCd battery networks. By continuously monitoring voltage, temperature, electrolyte level, ripple, ground leakage, and hydrogen concentration, the system ensures extended service life, optimized maintenance, and full operational safety for mission-critical DC power systems.