Duracell Ni-MH manuale d’uso

T T Ni-MH Rechargeable Batteries able of Contents 1 Introduction 2 General Characteristics 3 Composition and Chemistry 3.1 Active Components: Positive and Negative Electrodes 3.2 Electrolyte 3.3 Cell Reactions 4 Battery Construction 4 .1 Basic Cell Construction 4.2 Cylindrical Cell Construction 4.3 Prismatic Cell Construction 5.1 General Characteri[...]

Ni-MH Rechargeable Batteries 1 1 2 2 Introduction Rapid advancements in electronic technology have expanded the number of battery-powered portable devices in recent years, stimulating consumer demand for higher -energy r echargeable batteries capable of delivering longer service between recharges or battery replacement. The trend towards smaller , [...]

Ni-MH Rechargeable Batteries 3 3 Composition and Chemistry A rechargeable battery is based on the principle that the charge /discharge pr ocess is reversible, that is, the energy delivered by the battery during dischar ge can be replaced or r estored by rechar ging. Nickel oxyhydroxide (NiOOH) is the active mate- rial in the positive electrode of t[...]

The sealed nickel-metal hydride cell uses the “oxygen-recombination” mechanism to prevent a build- up of pressure that may r esult from the generation of oxygen towards the end of charge and overcharge . This mechanism requires the use of a negative electr ode (the metal hydride /metal electrode) which has a higher effective capacity than the p[...]

4 Ni-MH Rechargeable Batteries 4 4 Battery Construction DURACELL standard-sized nickel-metal hydride batteries are constructed with cylindrical and prismatic nickel- metal hydride cells . DURACELL nickel-metal hydride batteries are a sealed construction designed for optimal perfor- mance and maximum safety . The batteries are manufactured to strict[...]

Ni-MH Rechargeable Batteries The basic differences between the prismatic c ell and the cylindrical cell are the construction of the electrodes and the shape of the can. Prismatic cells are designed to meet the needs of compact equipment where space for the battery is limited. The rectangular shape of the prismatic cell permits more efficient batter[...]

Ni-MH Rechargeable Batteries 5.1 General Characteristics The discharge characteristics of the nickel-metal hydride cell are very similar to those of the nickel- cadmium cell. The charged open circuit voltage of both systems ranges from 1.25 to 1.35 volts per cell. On discharge, the nominal voltage is 1.2 volts per cell and the typical end voltage i[...]

T ypically , when the current is higher and the temperature is lower , the operating voltage will be lower . This is due to the higher “IR” drop that occurs with increasing current and the cell’ s increas- ing resistance at the lower temperatures. However , at moderate discharge rates ( ≈ C/5), the effect of low temperature on the capacity [...]

Figure 5.4.1 compares the gravimetric and volumetric energy density of nickel-metal hydride and nickel-cadmium cells. As indicated, nickel-metal hydride cells deliver more energy per weight or volume than nickel-cadmium cells. 5.5 Constant Power Discharge Characteristics The output energy characteristic of nickel-metal hydride batteries under the c[...]

Ni-MH Rechargeable Batteries 5.7 Internal Impedance DURACELL nickel-metal hydride batteries have low internal impedance because they are manufactured using cells designed with thin plate electrodes which offer large surface areas and good conductivity . Figure 5.7.1 shows the change in internal impedance with depth of discharge . As demonstrated, t[...]

10 Ni-MH Rechargeable Batteries Although many years of premium performance can be enjoyed from a nickel-metal hydride battery that is properly handled, the capacity delivered in each charge/discharge cycle will eventually begin to decr ease. This inevitable decrease in capacity can be accelerated by overcharging, storage or usage at high temperatur[...]

6 6 Ni-MH Rechargeable Batteries 6.1 General Principles Recharging is the process of r eplacing energy that has been discharged from the battery . The subse- quent performance of the battery , as well as its overall life, is dependent on effective charging. The main crite- ria for effective charging are: • Choosing the appropriate rate • Limiti[...]

Duracell recommends the charge termination method described in Section 6.3.1. The voltage of the nickel-metal hydride battery during charge depends on a number of conditions, including charge current and temperatur e. Figures 6.1.3 and 6.1.4 show the voltage profile of the nickel- metal hydride battery at different ambient temperatures and charge r[...]

13 Ni-MH Rechargeable Batteries The following summary explains some of the recommended methods for charge contr ol. The charac- teristics of each of these methods are illustrated in Figure 6.2.1 . In many cases, several methods ar e employed, particularly for high rate charging. 6. 2. 1 T imed Charge Under the timed charge control method, the charg[...]

6 . 2 . 5 Delta T emperature Cutoff ( ∆ TCO) 6 . 2 . 6 Rate of T emperature Increase (dT/dt) 6 . 3 Charging Methods Ni-MH Rechargeable Batteries This technique measures the battery tempera- ture rise above the starting temperature during char ging and terminates the charge when this rise exceeds a pre- determined value. In this way , the influenc[...]

6. 3. 1 Duracell’ s Recommendation: Three-Step Charge Procedure 6. 3. 2 Low-Rate Charge ( ≈ 12 hours) 6. 3. 3 Quick Charge ( ≈ 4 hours) 6. 3. 4 Fast Charge ( ≈ 1 hour) Ni-MH Rechargeable Batteries Charging at a constant current at the C/10 rate with time-limited charge termination is a convenient method to fully charge nickel-metal hydride [...]

6. 3. 5 T rickle Charge 6 . 4 Thermal Devices 16 Ni-MH Rechargeable Batteries A number of applications require the use of batteries which are maintained in a fully-charged state. This is accomplished by trickle charging at a rate that will replace the loss in capacity due to self-dischar ge. In these applications, a trickle charge at a C/300 rate i[...]

7 7 Cycle and Battery Life 7.1 Cycle Life The cycle life of nickel-metal hydride batteries depends on the many conditions to which the battery has been exposed, as is true for all types of recharge- able batteries. These include such variables as: • T emperature during charge and dischar ge • Charge and discharge curr ent • Depth of discharge[...]

7 . 2 Battery Life T able 7 . 2 .1 Recommended Permissible Low Rate Charge 15 ° C to 30 ° C (59 ° F to 86 ° F) 0 ° C to 45 ° C (32 ° F to 113 ° F) Quick Charge 10 ° C to 30 ° C (50 ° F to 86 ° F) 10 ° C to 45 ° C (50 ° F to 113 ° F) Fast Charge 10 ° C to 30 ° C (50 ° F to 86 ° F) 10 ° C to 45 ° C (50 ° F to 113 ° F) T rickle[...]

8 8 Safety Considerations Duracell’ s nickel-metal hydride batteries are designed to ensure maximum safety . Each cell includes a resealable pressur e relief mechanism (safety vent) to prevent excessive build-up of pressur e in the cell in the event it is overcharged excessively , exposed to extreme high temperatures, or otherwise abused. Duracel[...]

20 Ni-MH Rechargeable Batteries T able 8 . 0 . 1 T est T est Conditions T est Results Flat Plate Crush T est Cell is crushed between No explosion, sparks, or flames. two flat surfaces. Impact T est A 20 lb. weight is dropped from No explosion, sparks, or flames. height of 2 feet on cell. Short Circuit T est* Sample is shorted until discharged. No e[...]

Ni-MH Rechargeable Batteries 21 9 9 Proper Use and Handling Nickel-metal hydride batteries can give years of safe and reliable service if they ar e used in accordance with recommended procedur es and are not abused. The batteries can be used in any operating position. Other than charging, the only maintenance that should be r equired is to keep the[...]

22 Ni-MH Rechargeable Batteries 9 . 3 Waste Management: Recycling and Disposal 9 . 2 T ransportation Procedures for the transportation of batteries are specified by the United States Department of T ransportation in the “Code of Federal Regulations,” CFR49, entitled “T ransportation.” Internationally , air transportation is specified by the[...]