Industrial Ni-Cd Batteries Standard Range Technical Manual Effective: October, 2009 Alpha Technologies
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Alpha Ni-Cd Pocket Plate Battery Technical Manual EN-Alpha-TMSR-001 Effective Date: October, 2009 Copyright© 2009 Alpha Technologies, Inc. member of The GroupTM NOTE: Photographs contained in this manual are for illustrative purposes only. These photographs may not match your installation. NOTE: Operator is cautioned to review the drawings and illustrations contained in this manual before proceeding.
Table of Contents 1. 0 Alpha Ni-Cd Pocket Plate Cell ..................................................................................................................... 6 1.1 Features. ...................................................................................................................................................................................6 1.2 Venting System .............................................................................................................................
Table of Contents 7.0 Installation and operating instructions.................................................................................................. 23 7.1 Receiving the battery ...................................................................................................................................................... 23 7.2 Storage .............................................................................................................................................................
1.0 Alpha Ni-Cd pocket plate cell 1.1 Features 1 2 1 Low-pressure, flame-arresting vent; prevents carbonate formation. 2 Safety terminal; Redundant leak protection minimizes carbonate formation. 3 Electrode edge; connected to pole bolt via hardware for high mechanical stability 4 Electrode frame; Comprised of electrode edge and side bars. Seals the plates and serves as a current collector Horizontal pockets; formed by perforated steel strips containing the active material.
1.0 Alpha Ni-Cd pocket plate cell, continued 1.2 Venting System Alpha batteries can be equipped with a normal flip-top vent or with a special gas drying as well as a flame arresting vent. The originated charging gases (hydrogen and oxygen), which occur during the charging process of Ni-Cd batteries carry also small electrolyte drops of the electrolyte solution.
1.0 Alpha Ni-Cd pocket plate cell, continued 1.3 Electrode frame The electrode frame of Alpha Ni-Cd-batteries consists of a right and a left side bar as well as the electrode edge which are connected by welding shaping the electrode frame. The electrode frame operates as a current collector and also seals the electrode plates. This procedure leads to an electrode design with high mechanical robustness but also ensures a reliable service for the complete lifetime of the battery. 1.
1.0 Alpha Ni-Cd pocket plate cell, continued 1.6 Distance plate The distance plate operates as an additional stabilization to prevent any movement of the electrodes. It is an additional feature for applications where vibrations are possible. 1.7 Cell cases The cell cases are made from a translucent polypropylene or polystyrene, which ensures a visual control of the electrolyte level.
2.0 Battery Range and Applications 2.1 Battery ranges KM ...PN NON-STOP In order to enable Alpha to offer an appropriate solution in accordance with the customer's requirements and to have a choice for any battery application existing on the market, Alpha Ni-Cd batteries are designed in four different performance ranges. This Alpha cell type is a further developed M type, which provides caused by a special perforation higher discharge currents for special application up to 1 hour.
3. 0 Electrochemistry of Ni-Cd batteries Oxidation of cadmium at the negative electrode Cd Cd 2+ + 2 e¯ Reduction of trivalent nickel ions to bivalent at the positive electrode Ni3+ + e¯ Ni2+ During charging the both reactions are reversed.
4.0 Operating Features 4.1 Capacity The capacity of nickel-cadmium batteries is rated in ampere-hours (Ah) and is the quantity of electricity at +20 °C (± 5 °C) which can supply for a 5 hour discharge after being fully charged for 7.5 hours at 0.2 C5. These figures and procedures are based on the IEC 60623 standard. According to IEC 60623, 0.2 C5A is also expressed as 0.2 I A.
4.0 Operating Features, continued 4.4 Impact of Temperature on Cell Performance and Available Capacity When sizing and choosing a battery the variations in ambient temperature and their influence on the cell performance have to be taken into consideration. Low ambient temperature conditions reduce the cell performance, but on the other hand operations with higher temperatures are similar to those at normal temperatures. The effect of low temperatures is increasing with higher rates of discharge.
4.0 Operating Features, continued 4.5 Impact of Temperature on Lifetime As with every battery system an increased temperature always reduces the expected service lifetime and although the Alpha Ni-Cd battery is designed to reach a lifetime of over 20 years this is also the case. The following graph is included to demonstrate that the reduction in lifetime of a Alpha Ni-Cd battery is many times lower than for a lead acid battery.
4.0 Operating Features, continued 4.7 Open Circuit Loss The state of charge of a Ni-Cd cell on open circuit slowly self-discharges. Ni-Cd batteries are affected significantly by temperature. The higher the temperature, the higher loss of capacity. Ni-Cd batteries self-discharge at a niminal rate of 2% per month at 20°C. Graph 4-3, Self-discharge of NiCd-accumulators (fully charged) 4.8 Cycling The Alpha Ni-Cd battery is designed to obtain a huge number of cycles in stationary standby operations.
4.0 Operating Features, continued 4.9 Water consumption and gas evolution At the final stage of the charging procedure of a NiCd battery the provided electrical energy cannot be fully absorbed but is absolutely necessary to reach the fully charged state of the cells. The difference between absorbed and provided energy leads to a break down of the electrolyte's water content into oxygen and hydrogen (electrolysis). This loss has to be compensated by topping up the cells with pure distilled water.
5.0 Battery Sizing Principles and methods of sizing of Alpha Ni-Cd-batteries for standby applications. All our Ni-Cd batteries used for standby floating applications are sized according to the international sizing method IEEE 1115. Alpha has developed a special calculation program which is available over the Internet and allows us to update it regularly.
5.0 Battery Sizing, continued 5.6 Floating Effect -Voltage Depression When a Ni-Cd battery operates at a fixed floating voltage over a certain period of time, a decrease of the voltage level of the discharge curve occurs. It begins after one week and reaches its peak in approximately 3 months. Since this effect reduces the voltage level of the battery it can be considered as reducing the performance and autonomy of the battery as well.
6. 0 Charging The Alpha Ni-Cd battery can generally be charged by all normal methods. Usually, batteries in parallel operation with charger and load are charged with constant voltage. For operations where the battery is charged separately from the load, charging with constant current is possible. Overcharging will not damage the battery but will lead to an increase of water consumption. 6.
6.0 Charging, continued 6.2 Charge acceptance The time required to fully charge a discharged Ni-Cd cell is dependant upon the amount of charging voltage per cell. The following charts illustrate the relationship between Voltage per Cell, level of charge and charging time in hours. Graph 6-1, Time to reach state of charge at charging voltages for fully discharged cells (M-Range: current limit 0.
6.0 Charging 6.2 Charge acceptance, continued Graph 6-3, Time to reach state of charge at charging voltages for fully discharged cells (H-Range: current limit 0.2 C5A) 6.3 Charge efficiency The charge efficiency depends mostly on the state of charge of the battery and the ambient temperature as well as the charging current. For much of its charge profile the Ni-Cd battery is charged at a high level of efficiency. But if the battery approaches a fully charged condition the charging efficiency decreases.
6.0 Charging, continued 6.4 Temperature Influence The electrochemical behaviour of the battery becomes more active if temperature increases, i.e. for the same floating voltage the current increases. If the temperature decreases the reverse occurs. Increasing the current increases the consumption of water and reducing the current could lead to an insufficient charging. For standby application it is normally not necessary to compensate the charging voltage with the temperature.
7.0 Installation and Operation 7.1. Receiving the battery The cells are not to be stored in packaging, therefore, unpack the battery immediately after arrival. Do not overturn the package. The battery cells are equipped with a blue plastic transport plug. The battery can be delivered - Filled and charged/the battery is ready for installation.
7.0 Installation and Operation, continued 7.3. Installation, continued 7.3.3 Setting up Always pay attention to the assembly drawings, circuit diagrams and other separate instructions. The transport plugs have to be removed and replaced by the vent caps included in the accessories. If batteries are supplied “filled and charged” first the electrolyte level should be checked and if necessary topped up as described in point 3.4.
7.0 Installation and Operation, continued 7.3. Installation, continued 7.3.5 Commissioning A good commissioning is very important. The following instructions are valid for commissioning at 20°C till 30°C. For different conditions please contact manufacturer. Charge at constant current is preferable. If a site test is requested it has to be carried out in accordance with to IEC 60623. According to IEC 60623, 0.2 C5A is also expressed as 0.2 ItA. The reference test current is expressed as: Example: 0.
7.0 Installation and Operation, continued 7.3. Installation, continued 7.3.5 Commissioning 7.3.5.1 With Constant voltage If the charger´s maximum voltage setting is too low to supply constant current charging divide the battery into two parts to be charged individually. When the battery has been: Delivered unfilled and discharged: After a period of 5 hours from filling the electrolyte in the battery should be charged for 30 hours at the rated charging voltage of 1.65 V/cell. The current limit should be 0.
7.0 Installation and Operation, continued 7.4. Charging in operation 7.4.1 Continuous battery power supply (with occasional battery discharge) Recommended charging voltage for ambient temperatures + 20°C to + 25°C Do not remove the vent caps during float-, boost charge and buffer operation. The current limit should be 0.3 ItA maximum in general. 7.4.1.2 Two level charge Floating 1.40 - 1.42 V/cell Boost charge: 1.55 - 1.
7.0 Installation and Operation, continued 7.5. Periodic Maintenance, continued 7.5.2 Electrolyte check and topping up Check the electrolyte level and never let the level fall below the lower level mark "MIN". Use only distilled or deionized water to top-up the cells in accordance with IEC 60993. Experience will tell the time interval between topping-up. Refilling with electrolyte is only permissible if spilled electrolyte has to be replaced.
7.0 Installation and Operation, continued 7.6. Additional warning notes Ni-Cd batteries must not be operated or stored in the same room as lead acid batteries. In addition to this the charging gases from lead acid batteries must be kept away from Ni-Cd batteries by suitable precautions such as ventilation or hermetic isolation of the rooms. Tools for lead acid batteries must not be used for Ni-Cd batteries Do not place electrically conductive objects such as tools etc.
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