User manual GP BATTERIES NICKEL CADMIUM TECHNICAL HADBOOK

[. . . ] Nickel Cadmium Technical Hand Book Table of Contents 1 Introduction 1. 1 Overview 1. 2 NiCd Chemistry 1. 2. 1 Principle 1. 2. 2 Positive Electrode Chemistry 1. 2. 3 Negative Electrode Chemistry 1. 2. 4 Overall Reaction 1. 2. 5 Cell Pressure Management - Charge Reserve 1. 2. 6 Minimizing Damage During Deep Discharge - Discharge Reserve 1. 3 Cell Construction 3 3 3 3 3 3 3 3 4 5 3. 2. 4 Charge Control 3. 2. 5 Standard Charge 3. 2. 6 Trickle Charging 3. 2. 7 Charging Temperature 11 12 12 12 4 Battery Assembly 4. 1 Connection Between Cells 4. 2 Thermal Protection for Battery Packs 13 13 13 5 Configurations 6 Proper Use and Handling 6. 1 Restriction On Usage 6. 1. 1 Charging / Discharging Current 6. 1. 2 Reverse Charging 6. 1. 3 Parallel Charging 6. 1. 4 Charging / Discharging Temperature 6. 1. 5 Over-discharging / Overcharging 6. 2 Precautions for Designing Application Devices 6. 2. 1 Battery Compartment 6. 2. 2 Charging / Discharging / Operating Temperature 6. 3 Methods of Use 6. 3. 1 Operation 6. 3. 2 Connection Between Battery and Application Devices 6. 4 Precautions in Battery Handling 6. 5 Battery Maintenance 6. 5. 1 Regular Inspection 6. 5. 2 Storage 6. 5. 3 Battery Disposal 6. 5. 4 Transportation 14 15 15 15 15 15 15 16 16 16 16 16 16 16 16 17 17 17 17 17 2 Performance Characteristics 2. 1 Charging Characteristics 2. 1. 1 Overview 2. 1. 2 Charging Efficiency 2. 2 Discharge Characteristics 2. 2. 1 Discharge Voltage 2. 2. 2 Discharge Capacity 2. 2. 3 Polarity Reversal During Over-discharge 2. 3 Storage Characteristics 2. 3. 1 Overview 2. 3. 2 Storage Temperature 2. 3. 3 Storage Time 2. 3. 4 Storage Humidity 2. 3. 5 False ­dV 2. 4 Cycle Life 2. 4. 1 Overview 2. 4. 2 Ambient Temperature 2. 4. 3 Overcharge 2. 4. 4 Deep Discharge 2. 5 Safety 2. 6 Characteristics of Various Series 2. 6. 1 Standard Series 2. 6. 2 High Drain Series 2. 6. 3 High Temperature Series 2. 7 Memory Effect 6 6 6 6 6 6 6 6 8 8 8 8 8 8 8 8 9 9 9 9 9 9 9 10 10 7 Customer Application Questionnaire 8 Glossary 9 Note NOTICE TO READERS 18 20 22 3 Charging Method 3. 1 Overview 3. 2 Charging Method 3. 2. 1 Constant Current Charging 3. 2. 2 Constant Voltage Charging 3. 2. 3 Fast Charging 11 11 11 11 11 11 The information in this technical handbook is generally descriptive only, and is not intended to make or imply any guarantee or warranty with respect to any cells and batteries. Cell and battery designs are subject to modification without prior notice. Performance of a battery should be based on its corresponding data sheet and product specification. 1 2 1 Introduction 1. 1 Overview Nickel Cadmium (NiCd) is one of the most established a m o n g s t t h e va r i o u s c o m m e r c i a l l y ava i l a bl e rechargeable battery systems. The energy density of NiCd batteries are lower than the newer battery systems, such as Nickel Metal Hydride and LithiumIon. [. . . ] A -dV value of 0-20mV/cell is recommended when fast charging GP NiCd batteries. 1. 8 1. 7 Voltage (V) 1. 6 1. 5 1. 4 1. 3 1. 2 1. 1 0 20 40 60 80 -dV 100 120 140 160 180 200 % of Input Capacity b) Charging time control (back up only) An easier way to control fast charging of GP NiCd batteries is to control the elapsed time following commencement of charging. However, it is not recommended as the only cut-off method due to overcharging. A charging time between 120-140% of the cell nominal capacity is recommended. c) Battery temperature control As increased ambient and cell temperatures result in high cell inter nal pressure, it is highly recommended to have temperature control backup for safety and cell performance. When fast charging GP NiCd batter ies, the cut-off temperature is recommended to be controlled at 55°C. 3. 2. 5 Standard charge Apart from fast charging, GP NiCd batteries can also be charged at a lower current rate of 0. 1C. As this charging method is less severe, charge termination at 160% nominal capacity input is recommended (to help avoid extended overcharging of the battery). Also, in some applications where overcharging is necessar y, GP NiCd batteries can endure 0. 1C continuous charging for about one year. 3. 2. 6 Trickle charging In most applications - where cells and batteries need to be in a fully charged condition - maintaining a trickle charge current to compensate for the loss of capacity (due to self-discharge) is recommended. The suggested trickle charge current to be used is 0. 05C to 0. 1C. 3. 2. 7 Charging temperature As ambient temperature affects charging efficiency and cell reliability, it is important to select a suitable temperature for optimizing charging performances. Generally speaking, a temperature within 10°C to 45°C will yield the highest efficiency, which begins to drop at or above 45°C. Conversely, repeated charging at less than 0°C may cause cell internal pressure build-up, resulting in electrolyte leakage as in high temperature conditions. For these reasons, GP NiCd batteries can be charged at temperatures of 0°C to 45°C under standard charging conditions, but preferably at 10°C to 45°C under fast charging conditions. 11 12 4 Battery Assembly 4. 1 Connections Between Cells The resistance spot-welding method is to be used when NiCd cells are connected in a series, to avoid an excessive increase in cell temperature, which would occur if soldered on directly. Lead used for cell connections should be nickel-plated or pure nickel measuring 0. 1mm to 0. 4mm in thickness and 3mm to 6mm in width. The temperature of NiCd cells rises when the charge gets close to completion. Temperature increase is greater for a battery pack than for a single cell, due to the fact that the pack does not really allow for the d i s s i p a t i o n o f h e a t . T h e p r o bl e m i s f u r t h e r exacerbated when the pack is enclosed in a plastic case. Air ventilation should be provided in the plastic case of batteries - to allow for egress of any gasses that may result from activation of the safety vent of cells after abuse. 5 Configurations 4. 2 Thermal Protection for Battery Packs Battery packs intended for fast charging methods should have a thermal protection device. A thermistor sensing the temperature inside the pack should be employed. It is also desirable to have a ther mostat/polyswitch and a thermal fuse installed in the battery pack to protect it from abnormal rises in temperature and external short-circuiting. Locations for safety devices in battery pack assembly are shown in the following diagrams. Designation System for Battery Packs An example: Number of cells Tag type code in a pack GP60AAS4B1P Model number Configuration Tag direction code code For battery packs with connectors, the last two characters will be used to specify connector type eg. GP60AAS4BMU. Standard Configurations for Battery Packs CODE : A Cells stacked in a vertical column CODE : B Cells arranged in a row CODE : G Cells stacked in 2 vertical columns of unequal number of cells CODE : S Cells stacked in multiple columns and layers CODE : T Cells arranged in a horizontal triangle CODE : W Cells arranged in horizontal zig-zag rows (in one or more layers) CODE : Y Cells arranged in a horizontal rectangle Tag Type Specifications Tag Direction Codes CODE : 1 CODE : 2 PCB solder tag CODE : 3 Double PCB pin at positive terminal and single PCB pin at negative terminal CODE : 4 Solder wire tag CODE : 5 Short strip tag CODE : 6 Lead wire CODE : P Pointing at 180° CODE : H Pointing at the same direction Polyswitch (+) Strip solder tag Connector Type Specifications GP Universal Plug - exclusively from GP offers distinctive features unparalleled in the market. [. . . ] Rated Capacity A nominal capacity available from a cell at specific discharge conditions. Safety Vent This is a device to release the gas when the internal pressure of the battery exceeds the pre-set value. Self-discharge The loss of capacity by a cell/battery during storage or in an unused condition. Separator The thin and porous membrane between the positive and negative electrodes to prevent short-circuit and hold the electrolyte. [. . . ]