Duracell Ni-MH Owner'S Manual Download Page 19 | Manualshive

Page: 19 / 23

background image

7.2 Battery Life

Table 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)

Trickle Charge

10

°

C to 30

°

C (50

°

F to 86

°

F)

10

°

C to 35

°

C (50

°

F to 95

°

F)

Discharge 0

°

C to 40

°

C (32

°

F to 104

°

F)

- 20

°

C to 50

°

C (-4

°

F to 122

°

F)

Storage, Short Term

10

°

C to 30

°

C (50

°

F to 86

°

F)

- 20

°

C to 50

°

C (-4

°

F to 122

°

F)

Storage, Long Term

10

°

C to 30

°

C (50

°

F to 86

°

F)

- 20

°

C to 35

°

C (-4

°

F to 95

°

F)

Table 7.2.1 Recommended and permissible temperature limits for operation and storage of DURACELL

nickel-metal hydride rechargeable batteries

.

18

Ni-MH Rechargeable Batteries

Charge rate and amount of charge input during

overcharging are also important factors affecting cycle
life. If the battery is charged at a rate that exceeds the
oxygen recombination rate, oxygen that is generated
during overcharge will not react, causing a build up in
gas pressure and a rise in temperature which will have
damaging effects on battery and cycle life. Prompt use
of an effective charge termination method when
deleterious overcharge begins will lessen the effect
on cycle life.

Cycle life is also affected by the depth of dis-

charge. Depending upon the charge termination method,
up to 500 cycles can be obtained with the battery being
fully discharged on each cycle (100 percent depth of dis-
charge, or “DOD”). Considerably higher cycle life can be
obtained if the battery is cycled at shallower charge/
discharges.

The same factors that affect cycle life affect

overall battery life. Operation or storage at extreme
temperatures, overcharging, cell venting and abusive
use will reduce battery life. Operation and storage of

batteries at or about room temperature (20

°

C or 68

°

F)

will maximize battery life. Recommended and permissi-
ble temperature limits are shown in

Table 7.2.1

.

Cycle and Battery Life (cont.)

«
...
17
18
19
20
21
...
»

Summary of Contents for Ni-MH

Page 1: ...arge 5 7 Internal Impedance 5 8 Self Discharge and Charge Retention 5 9 Voltage Depression Memory Effect 6 1 General Principles 6 2 Techniques for Charge Control 6 2 1 Timed Charge 6 2 2 Voltage Drop V 6 2 3 Voltage Plateau zero V 6 2 4 Temperature Cutoff 6 2 5 Delta Temperature Cutoff TCO 6 2 6 Rate of Temperature Increase dT dt 6 3 Charging Methods 6 3 1 Duracell s Recommendation Three Step Char...

Page 2: ...l hydride battery technology is at a very early stage of maturity and manufacturers such as Duracell have identified many opportunities to improve battery performance These improvements will make DURACELL nickel metal hydride batteries an attractive power source for 3C devices for many years to come General Characteristics Many of the operating characteristics of the sealed nickel metal hydride re...

Page 3: ... the use of AB5 instead of AB2 alloys AB5 alloys offer better corrosion resistance characteris tics resulting in longer cycle life and better recharge ability following storage The composition of the metal alloy is formulated for optimal stability over a large number of charge discharge cycles Other important properties of the alloy include Large hydrogen storage capability for high energy density...

Page 4: ... become fully charged and pressure does not build up The charge current however must be con trolled at the end of charge and during overcharge to limit the generation of oxygen to below the rate of recombination Thus charge control is required to pre vent the build up of gases and pressure Duracell rec ommends that continuous overcharge not exceed C 300 for optimal performance As shown in Figure 3...

Page 5: ...to whichthe nickel compounds are pasted Similarly the negative electrode is a perforated nickel plated steel foil onto which the plastic bonded active hydrogen storage alloy is coated The assembly of a cylindrical cell is shown in Figure 4 2 1 The electrodes are separated by the sepa rator which is a synthetic non woven material that serves as an insulator between the two electrodes and as a mediu...

Page 6: ...and negative electrodes are interspaced by separator sheets The assembly is then placed in a nickel plated steel can and the electrolyte is added The positive electrodes are connected to the metal lid with a tab The cell is then sealed by crimping the top assembly to the can The top assembly incorporates a resealable safety vent a metal lid and a plastic gasket that is similar to the one used in t...

Page 7: ... Effect of Discharge Rate and Temperature Typical discharge curves for DURACELL nickel metal hydride batteries under constant current loads at various temperatures are shown in Figures 5 2 1 to 5 2 3 Discharge voltage is dependent on discharge current and discharge temperature FIGURE 5 1 1 1 5 1 4 1 3 1 2 1 1 1 0 9 Voltage V Ampere Hour Capacity Comparison of discharge voltage and capacity of same...

Page 8: ...racteristics of the battery are affected moderately at higher tempera tures At lower discharge temperatures performance decreases more significantly caused primarily by the increase in internal resistance Similarly the effects of temperature on performance are more pronounced at higher discharge rates The capacity of the battery decreases more noticeably as the current increases particularly at lo...

Page 9: ...onnected in series the greater the possibility of a cell being fully discharged and driven into overdischarge and polarity reversal During reversal hydrogen gas evolves from the positive electrode Hydrogen gas will be reabsorbed by the negative electrode and eventually oxygen gas will evolve from the negative electrode Extended overdischarge will lead to elevated cell pressure and opening of the s...

Page 10: ...d at 20 C and 45 C 68 F and 113 F particularly after 30 days Generally long term storage of a nickel metal hydride battery in either a charged or discharged condi tion has no permanent effect on capacity Capacity loss due to self discharge is reversible and nickel metal hydride batteries can recover to full capacity by proper recharging For example full capacity of a nickel metal hydride battery t...

Page 11: ...ften referred to as memory effect However the cell can be quickly restored to full capacity with a few full discharge charge cycles as indicated in Cycles 20 and 21 The voltage drop occurs because only a portion of the active materials in the cell is discharged and recharged during shallow or partial discharging The active materials that have not been cycled change in physical characteristics and ...

Page 12: ...go into overcharge the volt age profile of the nickel metal hydride battery does not exhibit as prominent a voltage drop as the nickel cadmium battery In Figure 6 1 2 the temperature profiles of the nickel metal hydride and nickel cadmium batteries are compared during charge at a constant current charge rate Throughout the first 80 percent of charge the temperature of the nickel cadmium battery ri...

Page 13: ...the charge rate Proper charging is critical not only to obtain maximum capacity on subsequent discharges but also to avoid high internal temperatures excessive over charge and other conditions which could adversely affect battery life 6 2 Techniques for Charge Control The characteristics of the nickel metal hydride battery define the need for proper charge control in order to terminate the charge ...

Page 14: ...e is terminated when the voltage begins to decrease This approach can be used with nickel metal hydride batteries but as noted in Section 6 1 the voltage drop of the nickel metal hydride battery is not as prominent as that of the nickel cadmium battery and may be absent in charge currents below the C 3 rate particularly at elevated temperatures The voltage sensing circuitry must be sensitive enoug...

Page 15: ...mperature increase of 1 C 1 8 F per minute with a back up temperature cut off of 60 C 140 F is recommended for dT dt A top up charge of C 10 for 1 2 hour is also recommended Usually this method is used in conjunction with other charge control techniques primarily to terminate the charge in the event that the battery reaches exces sive temperatures before the other charge controls activate A charge...

Page 16: ...tion method is used At the C 3 rate a dT dt termination method should not be used because the rate of temperature increase may not be sufficient to terminate the charge Another method of charging nickel metal hydride batteries in even less time is to charge at the C 2 to 1C constant current rates At these high charge rates it is essential that the charge be terminated early during overcharge Howev...

Page 17: ...ature and is used to cut off the charge or dis charge when a pre established internal bat tery temperature or current is reached These temperature cutoff TCO devices reset automatically after the overtempera ture or overcurrent condition has decreased below a reset threshold 3 Thermal Fuse This device is wired in series with the cell stack and will open the circuit when a predetermined temperature...

Page 18: ...dride batteries should be operated at or near room temperature 20 C or 68 F Repeated operation at extreme temperatures during charge and discharge will adversely affect the performance of the cells and thus the battery as shown graphically in Figure 7 1 1 Operation at high temperatures particu larly in the overcharged condition can cause the cell to vent releasing gas and possibly electrolyte thro...

Page 19: ...ds the oxygen recombination rate oxygen that is generated during overcharge will not react causing a build up in gas pressure and a rise in temperature which will have damaging effects on battery and cycle life Prompt use of an effective charge termination method when deleterious overcharge begins will lessen the effect on cycle life Cycle life is also affected by the depth of dis charge Depending...

Page 20: ...riters Laboratories in accordance with UL Standard 2054 Outline of Investigation for Household and Commercial Batteries Duracell successfully met all of the test criteria The tests required under this Standard and the results of the tests on DURACELL cells and batteries are summarized in Table 8 0 1 These tests cover operational and abusive conditions to which batteries may be exposed during their...

Page 21: ...fire or explosion on Test times rated capacity test conducted at C 3 charge rate Abusive Overcharge Sample is charged by Individual cells vented No explosion or fire Test power supply up to Maximum temperature on cell case was 200 watts until sample 200 C 392 F In batteries safety devices caused vents or explodes charging circuit to open periodically protecting battery as designed Maximum battery ...

Page 22: ...carefully followed 9 1 Care and Handling Disassembly The battery should not be disassembled opened or shredded under any conditions high short circuit currents and fire could result Nickel metal hydride cells contain an alkaline elec trolyte which can cause injury In the event that the electrolyte comes into contact with skin or eyes immediately flush with fresh water and seek medical advice Handl...

Page 23: ...tteries As a result a number of states and local governments have passed or are considering legislation which may require special procedures for the disposal of these batteries Thus state and local agencies should be contacted for their waste management guidelines Internationally procedures for waste management may vary from country to country In the absence of regulations or guidelines the follow...

Reviews:

No comments

Related manuals for Ni-MH

Brand: Panasonic Pages: 16

BOS R254K-UUI-LH10-S4

Brand: Balluff Pages: 196

Brand: zenitech Pages: 16

Brand: walimex Pages: 6

Brand: walimex Pages: 10

Brand: Paradyne Pages: 4

Brand: aquatherm Pages: 32

Brand: Metz Pages: 112

Brand: Digisol Pages: 25

480L - UPDATE V3.0

Brand: Lexicon Pages: 40

Brand: SeaSucker Pages: 9

Brand: HYPERLOW Pages: 4

Brand: mantona Pages: 24

Brand: Schumacher Electric Pages: 12

Brand: Ikelite Pages: 2

Brand: Acebil Pages: 11

Brand: Herrnhuter Pages: 2

Brand: Tessera4x4 Pages: 20

Brands by name

0 1 2 3 4 5 6 7 8 9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Popular brands

Load more brands