Nickel metal hydride batteries. Nickel-metal hydride accumulator batteries (Ni-MH). Application in hybrid cars

From the experience of operation

NiMH elements are widely advertised, as elements with high energy intensity, not afraid of cold and non-memory. Having bought a digital camera Canon PowerShot A 610, I naturally provided it with a memory with a memory of 500 posts of top quality, and to increase the duration of the filming, I bought 4 Nimh element with a capacity of 2500 mA * Hour of Duracell.

Compare the characteristics of the elements manufactured by industry:

Table 1.

From the table we see NiMH elements have a high energy capacity, which makes them preferred when choosing.

For thereafter, the DESay Full-Power Harger intelligent charger was purchased for charging NiMH elements with their workout. Elements it was charged qualitatively, but ... however, on the sixth charging, it ordered a long time to live. The electronics burned out.

After replacing the charger and multiple cycles, the charge-discharge, the batteries began to sit on the second - the third dozen shots.

It turned out that despite the assurances, NiMH elements also possess memory.

And most modern portable devices that use them, have built-in protection that turns off the power when a certain minimum voltage is reached. It does not allow complete battery discharge. The memory of the elements begins to play his role. Not fully discharged elements receive an incomplete charge and their container drops with each recharge.

High-quality chargers allow charging without loss of tank. But something I could not find on sale such for elements with a capacity of 2500mAh. It remains periodically to conduct their training.

Training NiMH elements

Everything written below does not apply to battery items having a strong self-discharge. . They can only be thrown away, the experience shows, they are not amenable to workout.

NiMH training elements consists in several (1-3) discharge cycles - charging.

The discharge is performed until the voltage is reduced on the battery element up to 1B. It is advisable to discharge the elements individually. The reason is that the ability to take a charge may be different. And it enhances when charging without workout. Therefore, it happens to premature triggering of protection for the voltage of your device (player, camera, ...) and subsequent charging of an unspecified item. The result of this increasing loss of tank.

The discharge must be performed in a special device (Fig. 3), which allows it individually for each element. If there is no voltage control, then discharge performed to a noticeable reduction in the brightness of the light bulb.

And if you spot the breaking time of the light bulb, you can determine the battery capacity, it is calculated by the formula:

Capacity \u003d discharge current x discharge time \u003d i x t (a * hour)

The battery with a capacity of 2500 mA hour is able to give a current of 0.75 and for 3.3 hours, if the resulting discharge is less, respectively, less residual capacity. And with a decrease in the capacity, you need to continue the battery training.

Now for the discharge of batteries elements, I use the device made according to the scheme shown in Fig.3.

It is made from the old charger and looks like this:

Only now light bulbs 4 pieces, as in Fig. 3. I must say about the lights separately. If the light bulb has a discharge current equal to a nominal value for a given battery or a slightly smaller one can use it as a load and indicator, otherwise the light is only indicator. Then the resistor should have such a magnitude that the total resistance of EL 1-4 and the resistor-parallel resistor R 1-4 was about 1.6 ohm. The light bulb on the LED is unacceptable.

An example of a light bulb that can be used as a load - this is a crypton light bulb for a pocket lamp at 2.4 V.

A special case.

Attention! Manufacturers do not guarantee the normal operation of batteries when charging currents exceeding the accelerated charging current I values \u200b\u200bshould be less than the battery capacity. So for batteries with a capacity of 2500ma * hour it should be below 2,5A.

It happens that NiMH elements after discharge have a voltage of less than 1.1 V. In this case, it is necessary to apply the reception described in the above article in the journal the world of PC. An element or sequential group of elements is connected to a power source through a 21 W car light bulb.

Get your attention again! Such elements must be checked self-discharge! In most cases, it is elements with reduced voltage have an increased self-discharge. These elements are easier to throw out.

Charging is preferred individual for each element.

For two elements, 1.2 voltage in the charging voltage should not exceed 5-6V. With forced charging, the light bulb is simultaneously indicator. When the brightness of the light bulb can be checked the voltage on the NiMH item. It will be more than 1.1 V. Usually, this initial, forced charging takes from 1 to 10 minutes.

If the NiMH element, with a forced charging, during a few minutes does not increase the voltage, heats up - this is a reason to remove it with charging and discard.

I recommend using charging devices only with the possibility of training (regeneration) of elements when recharging. If there are no such, then after 5-6 working cycles in the equipment, without waiting for the full loss of the tank, to produce their training and reject elements having a strong self-discharge.

And they will not let you down.

In one of the forums commented on this article "written stupidly, but nothing else"So this is not" stupidly ", but simply and available to perform in the kitchen to everyone who needs help. Those. The most simple as possible. Advanced can put the controller, connect the computer, ......, but this is another history.

To not seem stupid

There are "smart" chargers for NIMH elements.

This charger works with each battery separately.

He can:

1. individually work with each battery in different modes,
2. charge batteries in fast and slow mode,
3. individual LCD Display for Kazado Battery Compartment,
4. regardlessly charge each of the batteries,
5. charge from one to four batteries of different tanks and sizes (AA or AAA),
6. protect the battery from overheating
7. protect each battery from recharging,
8. determination End of voltage charging
9. define faulty batteries
10. pre-discharge the battery to residual voltage,
11. restor old batteries (charge-discharge training),
12. check battery capacity,
13. display on the LCD display: - charge current, voltage, reflect the current container.

Most importantly, I emphasize this type Devices allow you to work individually with each battery.

According to user reviews, such a charger allows you to restore most of the batteries running, and the serviceable exploit the entire guaranteed service life.

Unfortunately, I did not use such a charger, because it is simply impossible to buy it in the province, but in the forums you can find many reviews.

The main thing is not to charge on large currents, despite the declared mode with currents of 0.7 - 1a, it is still a small-sized device and can dispel the power of 2-5 W.

Conclusion

Any restoration of NIMH batteries is strictly individual (with each individual element) work. With constant control and rejection of non-charging elements.

And it is best to engage them with restoration using intelligent chargers that allow you to individually perform rejection and a charge cycle - a discharge with each element. And since there are no such devices that are automatically working with batteries of any capacity, then they are intended for elements of a strictly defined container or must have controlled charge currents, discharge!

This article about nickel-metal hydride (NI-MH) batteries have long been a classic on the expanses of the Russian Internet. I recommend to get acquainted ...

Nickel-metal hydride (NI-MH) batteries in their design are analogs of nickel-cadmium (Ni-CD) batteries, and in electrochemical processes - nickel-hydrogen batteries. The specific energy of the Ni-Mh of the battery is significantly higher than the specific energy of Ni-Cd and hydrogen batteries (Ni-H2)

Video: Nickel-Metal Hydride Batteries (NIMH)

Comparative batteries

*** A large scatter of some parameters in the table is caused by various assignments (structures) of batteries. In addition, the table does not take into account the data on modern low self-discharge batteries.

History Ni-MH Battery

The development of nickel-metal-hydride (NI-MH) batteries began in the 50-70s of the last century. As a result, a new method was created to preserve hydrogen in nickel-hydrogen batteries, which were used in spacecraft. In the new element, hydrogen accumulated in alloys of certain metals. Alloys that absorb hydrogen in the amount of 1000 times more of their own volume were found in the 1960s. These alloys consist of two or more metals, one of which absorbs hydrogen, and the other is a catalyst that contributes to the diffusion of hydrogen atoms into the metal lattice. The number of possible combinations of metals used is practically unlimited, which makes it possible to optimize the properties of the alloy. To create Ni-MH batteries, it took the creation of alloys, workable at low pressure hydrogen and room temperature. Currently, work on the creation of new alloys and technologies for their processing continues throughout the world. Nickel alloys with rare-earth group metals can provide up to 2000 battery discharge cycles with a decrease in the tank of the negative electrode by no more than 30%. The first Ni-Mh battery, in which LANI5 alloy was used as the main active material of the metal hydhydride electrode, was patented by Bill in 1975 in early experiments with metal hydride alloys, nickel-metal hydride batteries worked unstable, and the required battery capacity was not achieved. Therefore, the industrial use of Ni-Mh batteries began only in the mid-80s after creating a La-Ni-Co alloy, which allows electrochemically reversible to absorb hydrogen for more than 100 cycles. Since then, the design of Ni-MH batteries was continuously improved towards increasing their energy density. The replacement of the negative electrode allowed to increase by 1.3-2 times the tab of the active masses of the positive electrode, which determines the battery capacity. Therefore, Ni-MH batteries have a significantly higher specific energy characteristics compared to Ni-CDs. The success of the spread of nickel-metal hydride batteries was provided, high energy density and non-target materials used in their production.

Basic Ni-MH batteries processes

In Ni-Mh, the batteries are used as a positive electrode, an oxide nickel electrode is used, as in the nickel-cadmium battery, and the electrode of nickel alloy with rare-earth metals, absorbing hydrogen, is used instead of a negative cadmium electrode. At the positive oxide nickel electrode NI-MH of the battery proceeds:

Ni (OH) 2 + OH- → Niooh + H 2 O + E - (charge) Niooh + H 2 O + E - → Ni (OH) 2 + OH - (discharge)

On the negative electrode, the metal with absorbed hydrogen turns into a metall hydride:

M + H 2 O + E - → MH + OH- (charge) MH + OH - → M + H 2 O + E - (discharge)

The overall reaction to the Ni-MH battery is written in the following form:

Ni (OH) 2 + M → Niooh + Mh (charge) Niooh + Mh → Ni (OH) 2 + m (discharge)

The electrolyte in the main tok-forming reaction is not involved. After the message of 70-80% of the capacity and when reloaded on an oxide nickel electrode, oxygen begins to be released,

2OH- → 1 / 2O 2 + H2O + 2E - (reload)

which is restored on a negative electrode:

1 / 2O 2 + H 2 O + 2E - → 2OH - (reload)

The two recent reactions provide a closed oxygen cycle. When the oxygen is reduced, an additional increase in the tank of the metal hydride electrode is also provided by the group's education.

Ni-MH Electrode Design Batteries

Metal-hydrogen electrode

The main material that determines the characteristics of the Ni-MH of the battery is hydrogen-absorbent alloy, which can absorb the volume of hydrogen, 1000 times higher than its own volume. Lani5 type alloys were obtained, in which part of the nickel is replaced by manganese, cobalt and aluminum to increase the stability and alloy activity. To reduce the cost, some manufacturers instead of lanthanne use MIS-Metal (MM, which is a mixture of rare earth elements, their ratio in the mixture is close to the ratio in natural ores), including a cerium, praseodymium and neodymium. In the charging and discharge cycle, there is an expansion and compression of a 15-25% crystal lattice of hydrogen-free alloys due to absorption and desorption of hydrogen. Such changes lead to the formation of cracks in the alloy due to an increase in internal voltage. The formation of cracks causes an increase in surface area, which is subject to corrosion when interacting with an alkaline electrolyte. For these reasons, the discharge capacity of the negative electrode gradually decreases. In the battery S. limited quantity Electrolyte, it generates problems associated with the redistribution of electrolyte. The corrosion of the alloy leads to the chemical passivity of the surface due to the formation of resistant to corrosion of oxides and hydroxides, which increase the overvoltage of the main to-forming reaction of the metal hydride electrode. The formation of corrosion products occurs with the consumption of oxygen and hydrogen from the electrolyte solution, which in turn causes a decrease in the amount of electrolyte in the battery and increase its internal resistance. To slow down unwanted dispersion processes and corrosion of alloys that determine the service life of Ni-Mh batteries, are used (in addition to optimizing the composition and production mode of alloy) two main methods. The first method is to microcapsulating the alloy particles, i.e. In the coating of their surface with a thin porous layer (5-10%) - by weight of nickel or copper. The second method that has found the most widespread use is currently processed the surface of the alloy particles in alkaline solutions with the formation of protective films permeable for hydrogen.

Oxidnonichel electrode

Oxide-nickel electrodes in mass production are manufactured in the following constructive modifications: lamella, negleous sintered (metal-ceramic) and pressed, including tablet. IN last years Stonely felt felt and polymeric electrodes begin to be used.

Wildlock electrodes

Wildlock electrodes are a set of interconnected perforated boxes (lamellae) produced from fine (0.1 mm thick) nickel-plated steel tape.

Sintered (metal ceramics) electrodes

the electrodes of this type consist of porous (with a porosity of at least 70%) of the metal ceramic base, in the pores of which the active mass is located. The basis is made of carbonyl nickel fine powder, which, in a mixture with ammonium carbonate or carbamide (60-65% nickel, the rest - filler) is handled, rolling or sprayed onto a steel or nickel grid. Then, the mesh with a powder is subjected to heat treatment in the reducing atmosphere (usually in the atmosphere of hydrogen) at a temperature of 800-960 ° C, and ammonium carbonate or carbamide decomposes and disappears, and the nickel sinters. The bases thus obtained have a thickness of 1-2.3 mm, the porosity of 80-85% and the radius of 5-20 μm. The base is alternately impregnated with a concentrated solution of nickel nitrate or nickel sulfate and heated to 60-90 ° with alkali solution, which encourages the deposition of oxides and nickel hydroxides. Currently, an electrochemical impregnation method is also used, in which the electrode is subjected to cathode treatment in a nitrate nitrate solution. Due to the formation of hydrogen, the solution in the pores of the plate is alleged, which leads to precipitation of nickel oxides and hydroxides in the pores of the plate. Foil electrodes are calculated to the varieties of sintered electrodes. Electrodes are made to a thin (0.05 mm) perforated nickel tape on both sides, by sprinkling, alcohol emulsion of nickel carbonyl powder containing binders, sintering and further chemical or electrochemical impregnation with reagents. The thickness of the electrode is 0.4-0.6 mm.

Pressed electrodes

Pressed electrodes are manufactured by pressing under pressure under pressure of 35-60 MPa active mass per grid or steel perforated tape. The active mass consists of nickel hydroxide, cobalt hydroxide, graphite and binder.

Metal melting electrodes

Milking electrodes have a highly phased base made of nickel or carbon fibers. The porosity of these bases is 95% or more. The felt electrode is made on the basis of a nickel-plated polymer or aleggita felt. The thickness of the electrode depending on its purpose is in the range of 0.8-10 mm. The active mass is entered into felt with different methods depending on its density. Instead of felt can be used penonicelReceived by nickelting polyurethane foam followed by annealing in a reducing environment. In a highly phased medium, it is usually made by the method of pasta with a nickel hydroxide, and a binder. After that, the base with the paste is dried and rolling. Felt and foam electrodes are characterized by a high specific capacity and a large resource.

NI-MH Battery Design

Ni-MH Cylindrical Batteries

Positive and negative electrodes separated by a separator are rolled in the form of a roll, which is inserted into the housing and closed with a sealing cover with a gasket (Figure 1). The lid has a safety valve that is triggered at a pressure of 2-4 MPa in case of a battery failure.

Fig.1. The design of the nickel-metal hydride (Ni-Mh) of the battery: 1-housing, 2-cover, 3-caulpacker valve, 4-valve, 5-callers of a positive electrode, 6-insulating ring, 7-depled electrode, 8-separoter, 9- Positive electrode, 10-insulator.

Ni-Mh Prismatic Batteries

In prismatic Ni-Mh batteries, positive and negative electrodes are placed alternately, and the separator is located between them. The electrode unit is inserted into a metal or plastic housing and closed with a sealing lid. On the lid, a valve or pressure sensor (Figure 2) is installed on the cover.

Fig.2. Battery NI-MH design: 1-housing, 2-cover, 3-caulpacker valve, 4-valve, 5-insulating gasket, 6-insulator, 7-depled electrode, 8-separotor, 9-positive electrode.

In Ni-MH, the batteries use an alkaline electrolyte consisting of con with the additive LiOH. As a separator in Ni-Mh batteries, non-woven polypropylene and polyamide are used with a thickness of 0.12-0.25 mm, treated with a wetter.

Positive electrode

Ni-MH batteries use positive oxide nickel electrodes similar to those used in Ni-CD batteries. In Ni-MH, the batteries are mainly used metal-ceramic, and in recent years - felt and polymer electrodes (see above).

Negative electrode

The practical application in Ni-MH batteries found five structures of the negative metal hydride electrodes (see above): - Lamanamed, when a hydrogen-absorbent alloy powder with a binder or without a binder, pressed into a nickel grid; - Penonicel, when the paste with the alloy and the binder is introduced into the pores of the pennionic basis, and then dry and presses (rollerly); - foil, when the paste with the alloy and the binder is applied to the perforated nickel or steel nickel-plated foil, and then dried and pressed; - rolled when the powder of an active mass consisting of an alloy and a binder is applied with rolling rolling (rolling) on \u200b\u200ba stretch nickel grille or copper grid; - sintered when the alloy powder is painted on a nickel mesh and then sinters in the atmosphere of hydrogen. The specific capacities of the metal hydride electrodes of different structures are close by value and are determined mainly, the capacity of the alloy used.

Characteristics of Ni-MH batteries. Electrical characteristics

Open chain tension

The value of the voltage of the open circuit of the UR.TS. Ni-MH-systems accurately determine the dependence of the equilibrium potential of the oxide-nickel electrode on the degree of nickel oxidation, as well as the dependence of the equilibrium potential of the metal hydride electrode on the degree of saturation of its hydrogen. 24 hours after the battery charge, the voltage of the open circuit of the charged Ni-MH battery is in the range of 1.30-1,35V.

Nominal discharge voltage

UR with the normalized current of the category IR \u003d 0.1-0.2C (C - the nominal battery capacity) at 25 ° C is 1.2-1.25V, the usual final voltage is 1B. Voltage decreases with increasing load (see Figure 3)

Fig.3. The discharge characteristics of the Ni-Mh of the battery at a temperature of 20 ° C and different normalized load currents: 1-0.2C; 2-1C; 3-2C; 4-3s

Battery capacity

With an increase in the load (reduction of the discharge time) and with a decrease in temperature, the capacity of the Ni-MH of the battery decreases (Figure 4). It is especially noticeable to reduce the temperature of the tank at high discharge rates and at temperatures below 0 ° C.

Fig.4. The dependence of the discharge capacity of the Ni-MH of the battery from temperature at different discharge currents: 1-0.2C; 2-1C; 3-3s

Safety and life of Ni-MH batteries

When stored, the Ni-MH battery is self-discharge. After a month, at room temperature, the loss of the container is 20-30%, and with further storage, the losses decrease to 3-7% per month. The rate of self-discharge increases with increasing temperature (see Figure 5).

Fig.5. The dependence of the discharge capacity of the Ni-Mh battery from the time of storage at different temperatures: 1-0 ° C; 2-20 ° C; 3-40 ° C.

Charging Ni-Mh Battery

The operation (number of discharge-charging cycles) and the battery life of the Ni-MH is largely determined by the operating conditions. Working decreases with increasing depth and discharge speed. The operation depends on the charge rate and the method of controlling its ending. Depending on the type of Ni-Mh batteries, operation modes and operating conditions, batteries provide from 500 to 1800 discharge-charging cycles at a discharge depth of 80% and have a service life (on average) from 3 to 5 years.

To ensure reliable operation of the NI-MH battery during the guaranteed period, you must follow the recommendations and manual of the manufacturer. The highest attention should be given to the temperature regime. It is advisable to avoid recess (below 1B) and short circuits. It is recommended to use Ni-MH batteries for destination, avoid combinations of used and unused batteries, not solder directly to the battery of the wire or other parts. Ni-MH batteries are more sensitive to reload than Ni-CD. A relear may result in thermal acceleration. Charging is usually done with a current iz \u003d 0.1C for 15 hours. Compensation recharge is made current iz \u003d 0.01-0.03c for 30 hours or more. Accelerated (for 4 to 5 hours) and fast (1 hour) charges are possible for Ni-MH batteries having highly active electrodes. Under such charges, the process is controlled by changing the temperature ΔT and voltage ΔU and other parameters. Fast charge applies, for example, for NI-MH batteries, feeding laptops, cell phones, electric tools, although in laptops and cell phones are mainly used by lithium-ion and lithium polymer batteries. A three-stage charge method is also recommended: the first step of the rapid charge (1C and higher), the charge at a speed of 0.1C for 0.5-1 hours for final recharging, and the charge at a speed of 0.05-0.02c as a compensation recharge. Information on the charge methods Ni-MH batteries is usually contained in the manufacturer's instructions, and the recommended charging current is specified on the battery case. Charging voltage UZ at З \u003d 0.3-1С lies in the range of 1.4-1.5V. Due to the release of oxygen on a positive electrode, the amount of dedicated electricity during charge (qz) is greater than the discharge capacity (CP). At the same time, the return on the tank (100 cf / qz) is 75-80% and 85-90%, respectively, for disk and cylindrical Ni-Mh batteries.

Charge and discharge control

To exclude NI-MH rechargeable batteries, the following charge control methods can be applied with the corresponding sensors installed in batteries or chargers:

• the discontinuation method at the absolute temperature of Tmax. The battery temperature is constantly monitored during the charge process, and when the maximum value is achieved, the fast charge is interrupted;
• the discontinuation method for the rate of change of temperature ΔT / ΔT. When using this method, the steepness of the temperature curve of the battery is constantly monitored during the charge process, and when this parameter becomes above a definitely set value, the charge is interrupted;
• the method of termination of the charge on the negative tension delta -ΔU. At the end of the battery charge in the implementation of the oxygen cycle, its temperature begins to increase, leading to a decrease in voltage;
• the method of stopping the charge at the maximum charge t;
• method for the cessation of charge at the maximum pressure PMAX. Usually used in prismatic batteries of large sizes and tanks. The level of permissible pressure in the prismatic battery depends on its design and lies in the range of 0.05-0.8 MPa;
• the charge method at the maximum voltage Umax. It is used to disconnect the charge of batteries with high internal resistance, which appears at the end of service life due to lack of electrolyte or under reduced temperature.

When applying the Tmax method, the battery can be too recharged if the ambient temperature decreases, or the battery may not be charged enough if the ambient temperature increases significantly. The ΔT / ΔT method can be used very effectively to stop the charge at low ambient temperatures. But if at higher temperatures only this method, the batteries inside the batteries will be heated to undesirable high temperatures before Δt / Δt value can be achieved for shutdown. For a certain value Δt / Δt, a large input container can be obtained at a lower ambient temperature than with more high temperatures. At the beginning of the charge of the battery (as at the end of the charge) there is a rapid increase in temperature, which can lead to premature charge disconnection when applying the Δt / Δt method. To exclude this, charger developers use the initial delay delay timers of the sensor with the ΔT / ΔT method. The -ΔU method is effective for termination of charge at low ambient temperatures, and not at elevated temperatures. In this sense, the method is similar to the Δt / Δt method. To ensure the termination of the charge in cases where unforeseen circumstances prevent the normal charge interruption, it is also recommended to use a timer control regulating the duration of the charge operation (T method). Thus, for the rapid charge of the batteries with normalized currents 0.5-1C at temperatures of 0-50 ° C, it is advisable to use Tmax methods (with a turning off temperature of 50-60 ° C depending on the design of batteries and batteries), -ΔU (5- 15 mV per battery), T (usually for obtaining 120% rated tank) and umax (1.6-1.8 V per battery). Instead of the -ΔU method, Δt / Δt (1-2 ° C / min) method can be used with the initial delay timer (5-10 minutes). For the charge control as well, see the corresponding article after the rapid charge of the battery, in the chargers, provide for switching them to the normized current of 0.1C - 0.2C for a certain time. For Ni-MH batteries, the charge is not recommended when constant voltageSince the "thermal failure" of batteries can occur. This is due to the fact that at the end of the charge there is an increase in current, which is proportional to the difference between the power voltage and the battery voltage, and the battery voltage at the end of the charge is reduced due to temperature increase. At low temperatures, the charge rate must be reduced. Otherwise, oxygen will not have time to recombine, which will lead to an increase in pressure in the battery. For operation in such conditions, Ni-MH is recommended accumulators with high-art electrodes.

Advantages and disadvantages of NI-MH batteries

A significant increase in the specific energy parameters is not the only dignity of Ni-MH batteries in front of Ni-CD batteries. Failure to cadmium also means the transition to more environmentally friendly industries. It is easier to solve the problem of disposal of batteries failed. These advantages of Ni-MH batteries identified a faster increase in their production in all leading world battery companies compared to Ni-CD batteries.

Ni-MH batteries have no "memory effect" characteristic of Ni-CD batteries due to nickel formation in the negative cadmium electrode. However, the effects associated with the reload of the oxide-nickel electrode are saved. A decrease in the discharge voltage observed with frequent and long rearrangements in the same way as in Ni-CD batteries can be eliminated at the periodic implementation of several discharges up to 1B - 0.9V. Such discharges are enough to spend 1 time per month. However, nickel-metal hydride batteries are inferior to Nickel-Kadmiev, which they are called to replace, according to some operational characteristics:

• Ni-Mh batteries efficiently work in a narrower interval of operating currents, which is associated with limited desorption of hydrogen of the metal hydride electrode at very high discharge rates;
• Ni-MH batteries are narrowed temperature Range Operating: Most of them are inoperable at temperatures below -10 ° C and above +40 ° C, although in separate batteries series, the recipes adjustment ensured the expansion of temperature boundaries;
• during the charge of Ni-Mh batteries, more heat is allocated than when charging the NI-CD batteries, therefore, in order to prevent the battery overheating from Ni-MH batteries during the rapid charge and / or significant rearness, thermo fuses or thermo-relays are installed in them, which are located on the wall of one of the batteries in the central part of the battery (this refers to industrial accumulatory assemblies);
• Ni-MH batteries have an increased self-discharge, which is determined by the inevitability of the hydrogen reaction dissolved in electrolyte, with a positive oxide-nickel electrode (but, due to the use of special alloys of the negative electrode, it turned out to achieve a decrease in the self-discharge rate to the values \u200b\u200bclose to the indicators for Ni-CD batteries );
• the risk of overheating during the charge of one of the Ni-Mh battery batteries, as well as the ignition of the battery with a smaller capacity when the battery discharge increases with the mismatch of battery parameters as a result of long-term cycling, so the creation of batteries with more than 10 batteries is not recommended by all manufacturers;
• the loss of the tank of the negative electrode, which take place in the Ni-MH battery when discharge below 0 V, irreversible, which puts forward the stringent requirements for the rechargeable batteries in the battery and controlling the discharge process than in the case of using Ni-CD batteries, as a rule, is recommended to discharge to 1 B / AK in a minor voltage batteries and up to 1.1 V / AK in a battery of 7-10 batteries.

As noted earlier, the degradation of Ni-MH batteries is determined primarily with a decrease in the cycling of the sorbing ability of the negative electrode. In the charge-discharge cycle, the volume of the alloy crystal lattice is changed, which leads to the formation of cracks and subsequent corrosion when reactions with electrolyte. The formation of corrosion products occurs with the absorption of oxygen and hydrogen, as a result of which the total amount of electrolyte decreases and the internal resistance of the battery increases. It should be noted that the characteristics of Ni-Mh batteries substantially depend on the alloy of the negative electrode and the alloy processing technology to increase the stability of its composition and structure. This force the batteries manufacturers carefully to the choice of alloy suppliers, and battery consumers - to the manufacturer's choice.

According to the materials of the sites POWRINFO.RU, "Chip and Dip"

The main types of batteries:

• Ni-CD Nickel Cadmium Batteries
• Ni-Mh Nickel-Metal Hydride Batteries
• Li-ion Lithium-ion batteries

Ni-CD Nickel Cadmium Batteries

For rechargeable tools, nickel-cadmium batteries are actual standard. Engineers are well known for their advantages and disadvantages, in particular Ni-CD nickel-cadmium batteries contain cadmium - heavy metal of increased toxicity.

Nickel-cadmium batteries have the so-called "memory effect" of which the essence of which is reduced to the fact that during the charge of a non-fully discharged battery, its new discharge is possible only before the level from which it has been charged. In other words, the battery "remembers" the level of the residual charge, from which it fully charged.

So, when charging the non-fully discharged Ni-CD of the battery there is a decrease in its capacity.

There are several ways to combat this phenomenon. We describe only the easiest and most reliable way.

When using a battery tool with Ni-CD batteries, a simple rule should be adhered to: Charge only fully discharged batteries.

Pros Ni-CD Nickel Cadmium Batteries

• Low price Ni-CD Nickel Cadmium Batteries
• The ability to give the greatest load current
• The ability to quickly charge the rechargeable battery
• Saving high battery capacity up to -20 ° C
• A large number of charge-discharge cycles. For properly operation Similar batteries work perfectly and allow up to 1000 cycles of charge-discharge and more

Cons Ni-CD Nickel Cadmium Batteries

• The relatively high level of self-discharge - Ni-CD nickel-cadmium battery loses about 8-10% of its capacitance in the first day after a complete charge.
• During the storage of Ni-CD, the nickel-cadmium battery loses about 8-10% charge every month.
• After long-term storage, the Ni-CD capacitance of the nickel-cadmium battery is restored after 5 discharge cycles.
• To extend the service life of the NI-CD nickel-cadmium battery, it is recommended to completely discharge it every time to prevent the "memory effect"

Ni-Mh Nickel-Metal Hydride Batteries

These batteries are offered on the market as less toxic (compared to NI-CD nickel-cadmium batteries) and more environmentally safe, both in production and during disposal.

In practice, Ni-Mh nickel-metal hydride batteries truly demonstrate a very large capacity during dimensions and mass, slightly smaller than the standard Ni-CD nickel-cadmium batteries.

Due to the almost complete abandonment of the use of toxic heavy metals in the NI-MH design of nickel-metal hydride batteries, the latter after use can be disposed of quite safely and without environmental consequences.

Nickel-metal hydride batteries are somewhat reduced "memory effect". In practice, the "memory effect" is almost impaired due to a high self-discharge of these batteries.

When using Ni-Mh nickel-metal hydride batteries, it is desirable to discharge them in the process not completely.

Store NI-MH nickel-metal hydride batteries follows in a charged state. With a long (more than a month) interruptions in operation, batteries should be recharged.

Pluses Ni-Mh Nickel-Metal Hydride Batteries

• Non-toxic batteries
• Little "Memory Effect"
• Good performance at low temperature
• Large capacity compared to Ni-CD nickel-cadmium batteries

Cons Ni-Mh Nickel-Metal Hydride Batteries

• More expensive type of batteries
• The size of the self-discharge is about 1.5 times higher compared to Ni-CD nickel-cadmium batteries
• After 200-300 cycles of discharge-charge working capacity Ni-Mh nickel-metal hydride batteries decreases somewhat
• Ni-MH batteries Nickel-metal hydride batteries have a limited service life.

Li-ion Lithium-ion batteries

The undoubted advantage of lithium-ion batteries is a practically inconspicuous "memory effect".

Thanks to this wonderful Li-Ion property, the battery can be charged or recharge as needed based on the needs. For example, you can recharge a non-fully discharged lithium-ion battery before an important, responsible or long work.

Unfortunately, these batteries are the most expensive batteries. In addition, lithium-ion batteries have a limited service life, which is discharged by the discharge-charge cycles.

Summarizing it can be assumed that lithium-ion batteries are best suited for cases of constant intensive operation of the battery tool.

Pluses Li-Ion Lithium-ion batteries

• There is no "memory effect" and therefore it becomes possible to charge and recharge the battery as needed
• High Capacity Li-Ion Lithium-ion Batteries
• Small mass of Li-Ion lithium-ion batteries
• Record-low level of self-discharge - no more than 5% per month
• The possibility of fast charge Li-Ion lithium-ion batteries

Cons Li-Ion Lithium-ion batteries

• High cost Li-Ion lithium-ion batteries
• Reduced hours of operation at temperatures below zero degrees Celsius
• Limited service life

Note

From the practice of operating Li-Ion lithium-ion batteries in phones, cameras, etc. It can be noted that these batteries serve an average of 4 to 6 years and withstand about 250-300 discharge cycles during this time. At the same time, absolutely accurately noticed: more cycles discharge - shorter life Li-Ion lithium-ion batteries!

All these types of batteries have such important parameter as a container. The battery capacity shows how long it can feed the load connected to it. At the radio station, the battery capacity is measured in milliamme aperture. This characteristic is usually indicated on the battery itself.

For example, take the alpha 80 radio station and its 2,200 mAh battery. When the cycle of work 5/5/90, where 5% of the operation of the radio station for the transfer, 5% of the work on the reception, 90% of the time standby mode - the operating time of the radio station will be at least 15 hours. The lower this parameter of the battery, the less it can work.

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NIMH batteries - power supplies that are classified as an alkaline battery. They are similar to nickel-hydrogen batteries. But the level of their energy container is greater.

The internal composition of Ni MH batteries is similar to the composition of nickel-cadmium power supply. To prepare the positive output, this chemical element, nickel, minus - alloy, which includes hydrogen absorbing hydrogen metals.

Several typical designs of nickel metal hydride acb:

• Cylinder. To divide conductive conclusions, a separator is used to which the cylinder shape is specified. An emergency valve is concentrated on the lid, which is opened with a substantial increase in pressure.
• Prism. In such a nickel metal hydride battery, the electrodes are concentrated alternately. Separator applied for their separation. To accommodate the main elements, a housing prepared from plastic or a special alloy is used. To control the pressure into the composition of the cover, the valve is introduced or the sensor.

Among the advantages of such a power source are distinguished:

• Specific energy parameters of the power supply increase during operation.
• When preparing conductive elements, cadmium is not used. Therefore, problems with the utilization of the battery does not occur.
• The lack of a kind of "memory effect". Therefore, there is no need to increase the container.
• In order to cope with the discharge voltage (reduce it), experts perform the discharge of the unit to 1 1-2 times a month.

Among the limitations that are related to nickel-nickel hydhydride batteries are distinguished:

• Compliance with the installed interval of working currents. The excess of these indicators leads to a rapid discharge.
• Operation The power source of this type into severe frosts is not allowed.
• The composition of the battery is introduced thermal fuses, which determine the overheating of the unit, increase the temperature level to the critical indicator.
• Template to a self-disconstruction.

Charging Battery Nickel Metal Hydride

The process of charging nickel metal hydride batteries is associated with certain chemical reactions. For their normal flow, part of the energy is required, which is supplied by the charger, from the network.

The efficiency of the charging process is a part of the energy-produced power source that is intensified. The magnitude of this indicator may be varied. But at the same time get 100 percent efficiency is impossible.

Before charging metalhydride batteries, study the basic species that depend on the current value.

Drip charging type

Apply this type of charging for batteries must be carefully because it leads to a decrease in the operation period. Since the disconnection of the charger of this type is carried out manually, the process needs constant control, regulation. In this case, the minimum current indicator (0.1 of the total capacity) is set.

Since with such a charge Ni MH batteries, the maximum voltage is not installed, oriented only on a temporary indicator. To estimate the time gap use the parameters of the container that has a discharged power source.

The efficiency of the power supply charged in this way is about 65-70 percent. Therefore, manufacturers are not advised to use such chargers as they influence the operational parameters of the battery.

Fast recharging

Determining how Ni MH batteries can be charged in fast mode, manufacturers recommendations are taken into account. Current value - from 0.75 to 1 from a total capacity. The set interval is not recommended to exceed, since the emergency valves are turned on.

To charge NIMH batteries in fast mode, voltage is installed from 0.8 to 8 volts.

The efficiency of rapid charging NI MH power sources reaches 90 percent. But this parameter decreases as soon as charging time ends. If you do not turn off the charger in a timely manner, then the pressure will increase inside the battery, the temperature indicator will increase.

In order to charge Ni MH Akb, perform such actions:

• Pre-charging

This mode is introduced if the battery is completely discharged. At this stage, the current is from 0.1 to 0.3 from the tank. It is prohibited to use big currents. The time interval is about half an hour. As soon as the voltage parameter reaches 0.8 volts, the process stops.

• Transition to accelerated mode

The process of current extension is carried out for 3-5 minutes. During the entire time gap, the temperature is controlled. If this parameter reaches a critical value, the charger is turned off.

With a quick charge of nickel, metalhydride batteries current is set at 1 from a total capacity. It is very important to quickly disable the charging device, in order not to harm the battery.

To control the voltage use a multimeter or voltmeter. This contributes to the exception of false positives that adversely affect the performance of the device.

Part of the chargers for Ni MH batteries are not working at constant, but when pulsed current. Current supply is carried out with a set periodicity. Pulse current supply contributes to the uniform distribution of electrolytic composition, active substances.

• Additional and supporting charging

To replenish the total charge Ni MH of the battery at the last stage, the current indicator is reduced to 0.3 from the tank. Duration - about 25-30 minutes. Increase this time interval is prohibited, because it contributes to minimizing the operation period of the AKB.

Accelerated charging

Some models of the nickel cadmium batteries are equipped with an accelerated charging mode. To do this, charging current is limited by setting parameters at 9-10 from the tank. Reduced charge current is necessary as soon as the battery will be charged to 70 percent.

If the battery is charged in accelerated mode more than half an hour, the structure of the conductive conclusions is gradually collapsed. Experts recommend using such charging if you have certain experience.

How to charge power supplies, and also eliminate the probability of recharging? To do this, comply with such rules:

1. Monitoring the temperature mode Ni MH batteries. It is necessary to stop charging NIMH batteries, as soon as the temperature level is rapidly rising.
2. For NIMH power sources, temporary restrictions are installed that allow you to control the process.
3. Drop Ni MH batteries and charge them at a voltage, which is 0.98. If this parameter is significantly reduced, the charges are shutdown.

Restoration of nickel metalhydride power supplies

The recovery process of Ni MH batteries is to eliminate the consequences of the "memory effect" that are associated with loss of tank. The likelihood of such an effect increases if it is often incompletely charging the unit. The device is fixed by the lower boundary, after which the container is reduced.

Before restoring the power supply, such items are prepared:

• Light bulb required power.
• Charger. Before applying, it is important to clarify whether to use a charger to discharge.
• Voltmeter or multimeter to establish voltage.

A light bulb or a charger, which is equipped with the appropriate mode, is added to the battery with their own hands, in order to fully discharge it. After that, charging mode is activated. The number of recovery cycles depends on how long the battery was not operated. The workout process is recommended to repeat 1-2 times within a month. By the way, we restore in this way those sources that have lost 5-10 percent of the total capacity.

To calculate the lost container use a fairly simple method. So, rechargeable battery Fully charge, after which it is discharged and the container is measured.

This process is essentially simplified if you use the charger with which the voltage level can be monitored. Such aggregates are beneficial to use also because the probability of deep discharge is reduced.

If the degree of charge of nickel metalhydride batteries is not installed, then it is necessary to bring the light bulb. Using the multimeter, the voltage level is controlled. Only it is so prevented by the probability of a complete discharge.

Experienced specialists are carried out as the restoration of one element and a whole block. In the charging period, there is an alignment of the existing charge.

Restoring the power supply, which was operated for 2-3 years, with full charge, discharge does not always bring the expected result. All because the electrolytic composition and conductive conclusions gradually change. Before applying such devices, the electrolytic composition is restored.

View video about restoring such a battery.

Rules of use of nickel-metal hydride batteries

The duration of operation of NI MH batteries depends largely on whether overheating is not allowed or a substantial reload of the power supply. Additionally, the masters advised to consider the following rules:

• Regardless of how much power supplies will be stored, they must be charged. The charge percentage should be at least 50 of the total capacity. Only in this case there will be no problems during storage and maintenance.
• Rechargeable batteries of this type are sensitive to recharging, to excessive heating. These indicators affect the duration of use, the magnitude of the current. Special chargers are required for these power sources.
• Conduct training cycles for nickel-metal hydride power sources optional. Using a proven charger, the lost container is restored. The number of recovery cycles largely depends on what state the unit.
• Between the recovery cycles necessarily take breaks, and also study how to charge the battery is operated. This time interval is required in order to the unit cooled, the temperature level dropped to the desired indicator.
• The procedure of recharging or training cycle is carried out only in an acceptable temperature mode: + 5- + 50 degrees. If you exceed this indicator, the probability of the rapid failure increases.
• When charging, the voltage does not fall lower than 0.9 volts. After all, some chargers do not charge if this value is minimal. In such cases, it is allowed to lift the external source for power recovery.
• Cyclic recovery is carried out, provided that there is a certain experience. After all, not all chargers can be used to discharge the battery.
• Storage procedure includes a number simple rules. It is not allowed to keep the power supply in the outdoor or indoors in which the temperature level is reduced to 0 degrees. It provokes the frozen of the electrolytic composition.

If there is not one, but several power sources is carried out at a time, then the degree of charge is maintained at the established level. Therefore, inexperienced consumers carry out the restoration of the AKB separately.

NiMH batteries are effective power supplies that are actively used to complete various devices and aggregates. They stand out by certain advantages, features. Before their operation is required to account for basic use rules.

Video Pro NimH Batteries

The main difference between Ni-CD batteries and Ni-Mh batteries is the composition. The base of the battery is the same - it is nickel, it is a cathode, and the anodes are different. At the Ni-CD battery, the anode is a metal cadmium, the Ni-Mh battery anode is a hydrogen metal hydride electrode.

Each type of battery has its advantages and cons, knowing them, you can more accurately choose the battery you need.

Does the old charger suit a new battery if I change the Ni-CD on the Ni-MH battery or vice versa?

The principle of charge in both batteries is absolutely the same, so the charger can be used from the previous battery. The main battery data charging rule is that it is possible to charge them only after complete discharge. This requirement is a consequence of the fact that both types of batteries are subject to the "memory effect", although Ni-MH batteries have a minimum of batteries.

How to store Ni-CD and Ni-MH batteries?

The best location for storing the battery is a dry cool room, as the higher the storage temperature, the faster the battery self-discharge occurs. You can store the battery in any condition other than a complete discharge or full charge. The optimal charge is 40-60 %%. Once in 2-3 months should be carried out (due to the present self-discharge), the discharge and again charge up to 40-60 %% of the tank. Permissible storage for up to five years. After storage, the battery should be discharged, charge and then use in the usual mode.

Is it possible to use the batteries of a greater or less capacity than the battery from the original set?

Battery capacity is the operation time of your power tool from the battery. Accordingly, there is absolutely no difference from the battery capacity for the power tool. The actual difference will be only in the time of charging the battery, and the operation time of the power tool from the battery. When you select the battery capacity, you should be repeated from your requirements, if you need to work longer using one battery - the choice in favor of more capacious batteries, if complete batteries have completely suitable, then you should stop on accumulators or close by containers.