With the advent of rechargeable batteries, many processes in life have become easier. Especially when it comes to finger batteries. Digital cameras, camcorders, and other trendy gadgets can work up to 25 hours without recharging. And all this is achieved due to the electric current accumulated in the battery. An equally important advantage is long service life, which is possible due to the presence of a charger. What they are, how to choose the right one, and whether it is possible to assemble them with your own hands, we will find out further.

Finger batteries cannot work forever, requiring periodic recharging from a stationary power supply. The charger serves as a kind of conductor between the battery and the current, which the latter is able to accumulate for further use in gadgets. Since the market for models of devices operating on such batteries is extremely diverse, the batteries themselves differ accordingly (in terms of power and composition). In this regard, chargers have their own design features that allow servicing specific battery models.

Design features of devices

The necessary structural elements for all types of chargers are:

1. Voltage converter - capable of converting electrical current into alternating voltage used on demand.
2. Stabilizer - regulates the voltage level, preventing failure in the process of charging or burning the device due to power surges.
3. Control sensor - signals the beginning and end of the battery charging process.
4. Rectifier - responsible for the uninterrupted supply of charge to the battery, by equalizing the current strength to the required level.

The charging devices themselves are quite compact in size. Their fundamental difference lies in the form of rechargeable batteries, which are:

1. AA - this type of battery has a length of 50.4 mm and a diameter of 14.5 mm. The voltage is rated at 1.2 W, however, it may vary depending on the brand. Used in digital camcorders and cameras. In everyday life, such batteries are called finger-type.
2. AAA - have a smaller charge, so they require more frequent recharging. In the common people, they were called "little finger" or "mini finger".
3. 9V - a combined battery consisting of two batteries.

The charger can be either highly specialized, designed exclusively for a certain type of battery, or be universal. The intellectual property of versatility is achieved by completing a special adapter board that charges all types of batteries.

The principle of operation of the device and additional functions

Charging is carried out by supplying current from the mains. The converter evaluates the received amount of current, and then transfers it to the rectifier, which prevents voltage spikes. The control gauge shows when the battery is fully charged. Most often, this is an LED element that changes its color, depending on the level of charge.

In addition to charging, chargers can perform other functions that many users do not even know about.

Features of charging Ni─MH batteries, charger requirements and main parameters

Nickel-metal hydride batteries are gradually spreading in the market, and their production technology is being improved. Many manufacturers are gradually improving their characteristics. In particular, the number of charge-discharge cycles increases and the self-discharge of Ni─MH batteries decreases. This type of battery was produced to replace Ni─Cd batteries and little by little they are pushing them out of the market. But there remain some uses where nickel-metal hydride batteries cannot replace cadmium batteries. Especially where high discharge currents are required. Both types of batteries require proper charging to extend their service life. We have already talked about charging nickel-cadmium batteries, and now it's the turn to charge Ni-MH batteries.

In the process of charging, a battery undergoes a series of chemical reactions, to which part of the supplied energy goes. The rest of the energy is converted into heat. The efficiency of the charging process is that part of the supplied energy that remains in the “reserve” of the battery. The efficiency value may vary depending on the charging conditions, but is never 100 percent. It is worth noting that the efficiency when charging Ni─Cd batteries is higher than in the case of nickel metal hydride. The process of charging Ni─MH batteries occurs with a large heat release, which imposes its own limitations and features. For more information, read the article at the link provided.

Charging speed is most dependent on the amount of current supplied. What currents to charge Ni─MH batteries is determined by the selected type of charge. In this case, the current is measured in fractions of the capacity (C) of Ni─MH batteries. For example, with a capacity of 1500 mAh current 0.5C will be 750 mA. Depending on the charge rate of nickel-metal hydride batteries, there are three types of charging:

• Drip (charge current 0.1C);
• Fast (0.3C);
• Accelerated (0.5─1С).

By and large, there are only two types of charging: drip and accelerated. Fast and accelerated are practically the same thing. They differ only in the method of stopping the charge process.

In general, any charging of Ni─MH batteries with a current greater than 0.1C is fast and requires monitoring of some process termination criteria. Drip charging does not require this and can continue indefinitely.

Types of charging nickel-metal hydride batteries

Now, let's look at the features of different types of charging in more detail.

Drip charging of Ni─MH batteries

It is worth mentioning here that this type of charging does not increase the life of Ni─MH batteries. Since trickle charging does not turn off even after a full charge, the current is chosen very small. This is done so that the batteries do not overheat during prolonged charging. In the case of Ni─MH batteries, the current value can even be reduced to 0.05C. For nickel-cadmium, 0.1C is suitable.

With drip charging, there is no characteristic maximum voltage and only time can act as a limitation of this type of charging. To estimate the required time, you will need to know the capacity and initial charge of the battery. To calculate the charging time more accurately, you need to discharge the battery. This will eliminate the influence of the initial charge. The efficiency of drip charging Ni─MH batteries is at the level of 70 percent, which is lower than other types. Many nickel-metal hydride battery manufacturers do not recommend trickle charging. Although recently there is more and more information that modern models of Ni─MH batteries do not degrade during the drip charge process.

Fast charging nickel-metal hydride batteries

Manufacturers of Ni─MH batteries in their recommendations give characteristics for charging with a current value in the range of 0.75─1C. Keep these values ​​in mind when choosing how much current to charge Ni─MH batteries. Charging currents above these values ​​are not recommended as this may cause the safety valve to open to relieve pressure. Fast charging of nickel-metal hydride batteries is recommended at a temperature of 0-40 degrees Celsius and a voltage of 0.8-.8 volts.

The efficiency of the fast charging process is much greater than that of drip charging. It is about 90 percent. However, by the end of the process, the efficiency drops sharply, and the energy is converted into heat. Inside the battery, the temperature and pressure rise sharply. have an emergency valve that can open when pressure increases. In this case, the properties of the battery will be irretrievably lost. And the high temperature itself has a detrimental effect on the structure of the battery electrodes. Therefore, clear criteria are needed by which the charging process will stop.

The requirements for the charger (charger) for Ni─MH batteries are presented below. For now, we note that such chargers charge according to a certain algorithm. The general steps of this algorithm are as follows:

• determining the presence of a battery;
• battery qualification;
• pre-charging;
• transition to fast charging;
• fast charging;
• recharging;
• support charging.

At this stage, a current of 0.1C is applied and a voltage test is performed at the poles. To start the charging process, the voltage should be no more than 1.8 volts. Otherwise, the process will not start.

It is worth noting that the check for the presence of the battery is carried out at other stages. This is necessary in case the battery is removed from the charger.

If the memory logic determines that the voltage value is greater than 1.8 volts, then this is perceived as the absence of a battery or its damage.

Battery Qualification

Here, an approximate estimate of the battery charge is determined. If the voltage is less than 0.8 volts, then the fast charge of the battery cannot be started. In this case, the charger will turn on the pre-charge mode. Ni─MH batteries rarely discharge below 1 volt during normal use. Therefore, pre-charging is only activated in case of deep discharges and after long storage of the batteries.

Pre-charge

As mentioned above, pre-charging is enabled when Ni─MH batteries are deeply discharged. The current at this stage is set at 0.1÷0.3C. This stage is limited in time and is somewhere around 30 minutes. If during this time the battery does not restore the voltage of 0.8 volts, then the charge is interrupted. In this case, the battery is most likely damaged.

Transition to fast charging

At this stage, there is a gradual increase in the charging current. The increase in current occurs smoothly within 2-5 minutes. In this case, as in other stages, the temperature is controlled and the charge is turned off at critical values.

The charge current at this stage is in the range of 0.5÷1C. The most important thing at the stage of fast charging is the timely shutdown of the current. To do this, when charging Ni─MH batteries, control is used according to several different criteria.

For those who are not in the know, when charging, the voltage delta control method is used. In the process of charging, it constantly grows, and at the end of the process it begins to fall. Typically, the end of the charge is determined by a voltage drop of 30 mV. But this method of control with nickel-metal hydride batteries does not work very well. In this case, the voltage drop is not as pronounced as in the case of Ni─Cd. Therefore, to trigger a trip, you need to increase the sensitivity. And with increased sensitivity, the likelihood of false alarms due to battery noise increases. In addition, when charging several batteries, the operation occurs at different times and the whole process is smeared.

But still, stopping charging due to a voltage drop is the main one. When charging with a current of 1C, the voltage drop to turn off is 2.5÷12 mV. Sometimes manufacturers set detection not by a drop, but by the absence of a voltage change at the end of a charge.

At the same time, during the first 5-10 minutes of charging, the voltage delta control is turned off. This is due to the fact that when fast charging is started, the battery voltage can vary greatly as a result of the fluctuation process. Therefore, at the initial stage, control is turned off to eliminate false positives.

Due to the not too high reliability of charging off by voltage delta, control is also used according to other criteria.

At the end of the Ni─MH battery charging process, its temperature starts to rise. According to this parameter, the charge is turned off. To exclude the OS temperature value, monitoring is carried out not by absolute value, but by delta. Usually, a temperature increase of more than 1 degree per minute is taken as a criterion for terminating a charge. But this method may not work at charge currents less than 0.5C, when the temperature rises rather slowly. And in this case, it is possible to recharge the Ni-MH battery.

There is also a method for controlling the charging process by analyzing the derivative of the voltage. In this case, it is not the voltage delta that is monitored, but the rate of its maximum growth. The method allows you to stop fast charging a little earlier than the completion of the charge. But such control is associated with a number of difficulties, in particular, a more accurate voltage measurement.

Some chargers for Ni─MH batteries do not use direct current for charging, but pulsed current. It is delivered for 1 second at intervals of 20-30 milliseconds. As the advantages of such a charge, experts call a more uniform distribution of active substances throughout the volume of the battery and a decrease in the formation of large crystals. In addition, more accurate voltage measurement is reported in the intervals between current applications. As an extension of this method, Reflex Charging has been proposed. In this case, when a pulsed current is applied, the charge (1 second) and discharge (5 seconds) alternate. The discharge current is 1-2.5 times lower than the charge. As advantages, one can single out a lower temperature during charging and the elimination of large crystalline formations.

When charging nickel-metal hydride batteries, it is very important to control the end of the charging process by various parameters. There must be ways to abort the charge. For this, the absolute value of the temperature can be used. Often this value is 45-50 degrees Celsius. In this case, the charge must be interrupted and resumed after cooling. The ability to accept a charge in Ni─MH batteries at this temperature is reduced.

It is important to set a charge time limit. It can be estimated by the capacity of the battery, the magnitude of the charging current and the efficiency of the process. The limit is set at the estimated time plus 5-10 percent. In this case, if none of the previous control methods work, the charge will turn off at the set time.

Recharge stage

At this stage, the charging current is set to 0.1─0.3C. Duration about 30 minutes. Longer recharging is not recommended as it shortens battery life. The recharging stage helps to equalize the charge of the cells in the battery. It is best if, after a quick charge, the batteries cool down to room temperature, and then recharging starts. Then the battery will restore its full capacity.

Charging device for Ni─Cd batteries, often after the completion of the charge process, the batteries are transferred to drip charging mode. For Ni-MH batteries, this will only be useful if a very small current is applied (about 0.005C). This will be enough to compensate for the self-discharge of the battery.

Ideally, charging should have the function of switching on the maintenance charge when the battery voltage drops. Backup charging only makes sense if a sufficiently long time elapses between charging the batteries and using them.

Ultra-fast charging of Ni-MH batteries

And it is worth mentioning the ultra-fast battery charge. It is known that when charged to 70 percent of its capacity, a nickel-metal hydride battery has a charging efficiency close to 100 percent. Therefore, at this stage it makes sense to increase the current for its accelerated passage. Currents in such cases are limited to 10C. The main problem here is determining those very 70 percent of the charge at which the current should be reduced to a normal fast charge. This is highly dependent on the degree of discharge from which the battery charging began. High current can easily lead to overheating of the battery and destruction of the structure of its electrodes. Therefore, the use of ultra-fast charge is recommended only if you have the appropriate skills and experience.

General requirements for chargers for nickel-metal hydride batteries

It is not advisable to disassemble any individual models for charging Ni─MH batteries within the framework of this article. Suffice it to say that these can be narrowly focused chargers for charging nickel-metal hydride batteries. They have a wired charging algorithm (or several) and constantly work on it. Is there universal devices, which allow you to fine-tune the charging parameters. Eg, . Such devices can be used to charge various batteries. Including, and for, if there is a power adapter of the appropriate power.

It is necessary to say a few words about what characteristics and functionality a charger for Ni─MH batteries should have. The device must be able to adjust the charging current or automatically set it, depending on the type of batteries. Why is it important?

Now there are many models of nickel-metal hydride batteries, and many batteries of the same form factor may differ in capacity. Accordingly, the charging current must be different. If you charge with a current above the norm, there will be heating. If it is below the norm, then the charging process will take longer than expected. In most cases, the currents on the chargers are made in the form of "presets" for typical batteries. In general, when charging, manufacturers of Ni-MH batteries do not recommend setting a current of more than 1.3-1.5 amperes for type AA, regardless of capacity. If for some reason you need to increase this value, then you need to take care of forced cooling of the batteries.

Another problem is related to the charger power being cut off during the charging process. In this case, when the power is turned on, it will start again from the battery detection stage. The moment when fast charging ends is not determined by time, but by a number of other criteria. Therefore, if it passed, then it will be skipped when turned on. But the stage of recharging will take place again, if it has already been. As a result, the battery receives unwanted overcharging and excessive heating. Among other requirements for Ni-MH battery chargers is a low discharge when the charger is turned off. The discharge current in a de-energized charger should not exceed 1 mA.

It is worth noting the presence of another important function in the charger. It must recognize primary current sources. Simply put, manganese-zinc and alkaline batteries.

When installing and charging such batteries in the charger, they may well explode, since they do not have an emergency valve to relieve pressure. The charger is required to be able to recognize such primary current sources and not start charging.

Although it is worth noting here that the definition of batteries and primary current sources has a number of difficulties. Therefore, memory manufacturers do not always equip their models with similar functions.

AA and AAA batteries: which are better

AA and AAA size batteries are divided into three categories, "branded", "Chinese" and LSD(low self-discharge). The first two categories can be combined into one called "junk". You should not look at the big name like Duracell or Energizer and 3000Mah numbers - these are all batteries, let's call it instant use. I charged it, immediately inserted it into the device, snapped it off (or flashed it), put it back into the memory. These batteries self-discharge very quickly, even without load (up to 20% in the first day and up to 50% in the first week), they cannot deliver high current and die very quickly (one hundred charge-discharge cycles and into the trash), and the worst thing is that for batteries from the same box, the characteristics may differ by half.

LSD batteries have low self-discharge and high current efficiency. They are more expensive, the numbers are written on them half as much as on the samples from the first category, but these are honest numbers and more than 1000 charge-discharge cycles. LSD batteries are also good because they can be used in low-power or rarely used devices (clocks, remote controls, flashlights, etc.) - self-discharge is only 10% per year. The best of the batteries of the second category are Eneloop batteries.

An interesting fact: SkyRC chargers, which, as you know, produce the coolest chargers, have a separate program for charging Eneloop batteries. In fact, this is the same program as for charging conventional NiMH batteries, but it involves charging O larger currents. The Eneloop 2100mAh battery will easily charge in an hour with a current of 2A, from which ordinary nickel batteries will simply boil.

Chargers for AA/AAA batteries

They are divided into three categories: "branded", "Chinese" and good. The first two categories are combined into one. Charging from Durasel, Varta, Energizer, etc. - this is the same consumer goods as, only five times more expensive. Even four-channel ones can't do anything but charge. What else is needed? Control. As I said above, bad batteries already out of the box can have twice the characteristics. But even for good ones (I remind you, these are LSD batteries), the characteristics begin to jump after some time of use, for example, a year or two. Imagine that you put 4 batteries into the flash, about which you know only one thing for sure: they are fully charged. But the trouble is, three batteries have a nominal capacity, and you once accidentally dropped the fourth one and its capacity decreased by half. You put it in the flash, and it stops turning on after 20 shots. The end of batteries, you think, and throw the whole set into the trash, although you could buy one battery and use the set for many more years.

So here it is good memory they can show how discharged each battery is, how much was "filled" into each battery when charging, count the capacity of each battery, and the best ones can even restore it. the best of the inexpensive chargers today are, and its updated version. Chargers of the early 2000s, such as La Crosse (aka Technoline) and MAHA Powerex, I dare to call outdated ideologically.

There are more universal chargers. For example, SkyRC iMAX B6, original or copy (copy is much worse in measurement accuracy, firmware and software work). Its advantage is the ability to charge anything and anything, from charging batteries of radio-controlled models to lead-acid car and lithium batteries for cameras and mobile phones. Minus - excessive versatility greatly complicates the device, and in general, for full use, a basic understanding of the basics of electrical engineering is required, and you need to buy additional wires with connectors and sockets for each battery size.

The king of chargers for batteries of all (generally all) sizes today is, which can charge batteries of the types NiCd, Ni-MH, LiIon, LiFePO4, NiZn in banks of sizes C, D, AA, AAA, 18650, 14500, 16340, 32650, 14650 17670 10440 18700 18350 RCR123 AAAA 18500 18490 25500 13500 13450 16650 22650 17500 10340 17650 26500, 12340, 12500, 12650, 14350, 14430, 16500, 17350, 20700, 21700, 22500, 32600, Sub-C. In addition, the MC3000 has a Bluetooth interface, and can show the battery status directly on your smartphone. The only downside is the price. On the other hand, two separate chargers for nickel and lithium cost almost as much.

My review of NiMH batteries and chargers

I used Varta, Duracells and GPs and various Chinas for many years, and switched to Eneloop back in 2013, right after buying a Lacrosse charger to replace the deceased "cool four-channel" one from Duracell. With the help of La Crosse, I saw the mess that my "proprietary" batteries were like after Durasel's charging - a range in capacity from 600 to 2200 mAh and a loss of 30% of the charge during the first day.

The only batteries that matched their nominal capacity (surprisingly) and held their charge just fine were those purchased at the Gsyuasa Enitime sale in 2010. Googling, I found out that they are made according to the LSD standard and are in some way clones of the Sanyo Eneloop HR-3UTG. Googling a little more, I found that there are already HR-3UTGA and HR-3UTGB, which hold a charge even better. In general, there was money, so I switched to the latter, reasoning that the original is always better than the clone. Three years have passed - the flight is normal, the parameters have not changed. By the way, Gs Yuasa Enitime continues to serve (for the eighth year already) without complaints, out of 12 pieces, only one has lost its capacity.

1. Out of competition Panasonic Eneloop - in the Panasonic brand store on Aliexpress.
2. Of the inexpensive ones, this is green PKCELL. It holds three amperes, which, together with a small self-discharge, allows them to be classified as LSD (see).
3. Xiaomi ZMI ZI7 and ZI5. ZI7 is AAA, ZI5 is AA. Real LSD batteries. The capacity is lower than that of Eneloop (700 and 1800 mAh respectively), the price is .
4. Of course, "branded" manufacturers also have LSD batteries. For example, Varta Longlife Ready2Use, Duracell StayCharged or GP ReCyko+. But they, although they are prohibitively expensive (more expensive than the same enelups), are no better in terms of characteristics. The same applies to "simple", non-LSD batteries - some green ones are just as good as Duracell 2650, which are much more expensive. Three sets of Soshine and Duracell were purchased at the same time, served for two years and were sent for recycling. According to my feelings, Soshine and Duracell batteries are generally made at the same factory, they are so similar in characteristics.
5. Eneloop Pro are high capacity batteries. Like simple Eneloop, they can hold high currents and work normally in cold weather, but they live 4 times less: 500 cycles versus 2100 for Panasonic BK-3MCCE. And they self-discharge faster (-15% per year for Eneloop Pro versus -30% per 10 years for white fourth-generation Eneloop).

And finally, advice. The main rule when switching to good batteries is to choose some and buy several sets of them at once, since using batteries from different manufacturers (albeit of the same capacity) is inefficient due to different characteristics.
Say, all of them, when discharged from nominal to 0.9V (this is considered a full discharge), give 2000 mAh, but some batteries discharge faster in the range of 1.2–1.1 V, while others in the range of 1.1–1.0 V. Or they heat up differently under load. When they are installed in one set, due to different discharge curves, a situation may arise when one battery is discharged to zero and the remaining elements begin to charge it in the opposite direction, which will lead to an instant failure of the battery. Today you have four 2000mAh batteries, and tomorrow only three.

In 2013, I bought the first La Crosse BC 700 smart charger and Sanyo batteries, then, for lithium batteries, a universal charger, I immediately felt the difference. Since then, I regularly test chargers and batteries from other manufacturers, constantly update the fleet of batteries and follow the latest, so I can talk about batteries not just speculatively, but based on their use in the field.

Batteries and chargers relevant for 2019

The article is already 5 years old, but I constantly update it, so the above remains true for 2019. The chargers that I purchased in 2015 turned out to be of very high quality, this and the best in terms of price / quality ratio universal . In version 2.2, it is completely free from childhood diseases and to this day is the best purchase. It is sometimes found on sale under the brand name Zeepin with the same markings. A big plus of Opus 3100, in addition to the ability to charge lithium and nickel batteries at the same time (a switch is provided for charging LiHV and LiFePo4 4.2V/4.35V/3.7V), is forced cooling during charging, which reduces the likelihood of cans overheating (and this miracle can charge them with currents up to 2 amperes, which implies significant heating). The second plus is the possibility of using these chargers in a car with direct power from the on-board 12 volt network. Well, everything else is also at a high level - training, measuring internal resistance, charging with direct current for lithium and -ΔV for nickel batteries.

In terms of functionality, Liitocala repeats the Nitecore D4, because it does not know how to train batteries in automatic mode, but it charges perfectly and costs less.

A few words about chargers for 8 or more AA / AAA batteries

With rare exceptions, 8-cell chargers are either one quad charger (two batteries per channel) or two separate quad chargers in one housing.

For example, for $8 (like its noname counterpart called C808W for $7) it charges batteries in pairs (that is, it does not have 8 slots of 1.2 volts, but 4 dual slots of 2.4 volts). And, despite the 8 slots, the charge current for AA batteries is only 200 mA, which is five times less than normal chargers. Thus, while TangsPower T - 808C charges two sets of batteries, Opus will have time to charge five sets. Another limitation: you cannot charge one battery, the minimum number is two. Moreover, if you want to use the batteries longer, they must be equally discharged. Otherwise, the one with more charge will be recharged. This is rubbish, I mentioned it to demonstrate that more is not always better.

For $45, it can charge lithium! This, in fact, is all of its virtues. From the intelligence in it - the name, and 8 separate channels of 650 mA. It doesn’t even have a screen that will show you that charging has correctly understood the type of battery. It costs as much as three Liitokala, but does not even have a small screen to show the voltage and amount of the flooded current, not to mention the big screen, internal resistance testing, battery training, etc.

And finally, the champion of eight-cell chargers, . Price $63, excellent informative screen, the ability to charge Ni-MH 1.5V, LiFePO4 3.6V, Li-ion 4.2 V / 4.3 V / 4.35 V batteries of almost all sizes. Charge current 1A for each slot, the ability to set the charging mode for each slot separately. And you can even use it as a Powerbank. It costs like two opuses. But he does not know how to train and test batteries, because, first of all, this is a device for charging lithium batteries in the field (from the vehicle's on-board network), which has the ability to charge nickel as an option.

Accordingly, there is no positive effect from increasing the number of slots. In the first case, the device will charge the batteries in pairs (there is no question of any intelligence of such a device), in the second and third it is more efficient and cheaper to buy two separate chargers. For example, as I had before: one only for nickel AA / AAA, with the ability to restore batteries (and train them every six months), and the second without such an opportunity, but with support for lithium batteries. The advantages of such a scheme:

• eight NiMH batteries can be quickly charged at the same time (the key word is "fast", since the charge current in eight-cell chargers is usually lower);
• if necessary, train them (in your free time, 4 at a time);
• charge lithium batteries with a second charger (lithium does not need training)
• savings and the ability to buy one device first, and then buy a second one.

IN modern devices- flashes, cameras, etc. AA batteries are widely used. They are most often nickel-metal hydride (Ni-MH), less often nickel-cadmium (Ni-Cd, Ni-Cad).
Each of these types has its pros and cons:

• Ni-MH - quite capacious and stable, best suited for cameras, but suitable for flashes when fast charging is not required
• Ni-Cd - the least capacitive of all, but capable of delivering more current, even with a strong discharge - are best suited for flashes, as they provide a quick charge. Extremely toxic - cadmium from one battery can poison a huge amount of water, so now such batteries produce very little

Batteries of even the same type, for example, Ni-MH, even those produced by the same company, are very different. For example, more capacitance almost always means less current.
Charging nickel-metal hydride and nickel-cadmium (the most common AA batteries) is not so easy:

• For example, the charging current can be large or small. Small charging current means a very long charge, but the battery will be better charged.

  High charging current means very fast charging (with a lot of battery heat, which is why fast chargers are necessarily equipped with fans), but incomplete charging and faster battery wear. An ancient rule says "a good charge is provided by charging with a current equal to 0.1 of the battery capacity." Fast charging breaks this rule.

• There is also such a bad phenomenon as the "battery memory effect": incomplete discharge of the battery with subsequent charge means that the next time the battery will work to the state when it was not completely discharged last time - that is, it loses capacity.

  Nickel-cadmium are more susceptible to this effect than nickel-metal hydride. That is why it is so important to completely discharge the battery before its next charge (but it is also important not to overdo it here - because a battery discharge of up to 1 volt can permanently ruin the battery).

  The problem with the loss of capacity also occurs during normal battery operation - when batteries are used for a long time. However, the "memory effect" can be overcome by "training" batteries, that is, multiple full discharges and subsequent charges.

Personally, I had 2 chargers - a fast half-hour charger (by the way, there are even faster chargers, for example, fifteen-minute ones, and they are inexpensive and the brand seems to be quite good - Duracell) and a slow eight-hour charger. Both chargers are from good manufacturers (Duracell and Annsman).

Batteries charged with these different chargers behaved differently - the clear advantage of an 8-hour charge is clearly noticeable, because after charging an 8-hour charge, the batteries lasted noticeably longer. Therefore, most of the time I used an eight-hour charge, leaving a half-hour charge as a last resort.

Although advertising says that modern batteries of good models do not have this problem with "capacity loss due to the battery memory effect", but my experience (about 15 sets of 4 batteries in each set, all sets of various brands - specially bought different , both cheap and very expensive) suggests otherwise. That is, at different models indeed, during operation, there is a different loss of capacity - some have more, some have less, but advertising is lying - modern batteries are not completely free from problems with the "memory effect".

The most unpleasant thing is that bad batteries fail precisely in photography. It manifests itself like this - fully charged batteries die after several tens of frames (and sometimes after several frames, even dozens are not discussed). Sometimes the "law of meanness" works - the less time you have for shooting - the more worthless sets of batteries you find.

When this happened to me on a reportage shoot - the moments of which cannot be repeated - after the shooting, I bought several new sets of batteries. But when, after three months of operation at moderate loads (discharges-charges about once every 2 weeks for each set), several sets, including new ones, failed in a row on a leisurely object shooting after several flashes, I spent some time searching for information about normal chargers.

I found out another interesting thing - the ideal charging current, at which the batteries are charged to the maximum and the ideal charging time, depends on the capacity of the battery. And, therefore, there can be no better charging fully automatic charger. After all, AA batteries are not equipped with a feedback mechanism that could transmit any information (for example, at least information about the nominal capacity) to the charger. Of the most common batteries, only lithium-ion and lithium polymer batteries, but not AA.

It turns out that it is not at all easy to properly charge batteries without a feedback mechanism. Moreover, even new batteries should be "trained" before use. With batteries that have been lying for more than 3 months, you should also do a "training". Light "training" should also be done with batteries that have lain for a short time (more than 2 weeks and less than 3 months).

Since manually "training" batteries is very tedious, smart chargers are also being produced. And since the charging current and time and additionally necessary operations for "training" the battery depend on the battery itself - on its nominal capacity, actual capacity, idle time (storage time), features of the internal chemistry of the battery - that is, very, very smart chargers.

The use of very smart chargers allows you not to be on a responsible shoot with a full bag of fully charged, but very quickly depleting batteries, as happened to me several times. Well, in general, working with batteries will become more convenient - they will last much longer, less often you will need to buy new ones.
The following very smart chargers are currently known to me:

• Maha Energy PowerEx MH-C9000 WizardOne Charger-Analyzer for 4 AA / AAA
• La Crosse Technology BC-900 AlphaPower Battery Charger (also known as Techno Line BC900, Techno Line iCharger)
• La Crosse Technology BC-700 (differs from the BC-900 in a reduced charge current, but this is enough for the eyes)

Some more information about batteries for photographers (AA Ni-MH, Ni-Cd) and how to properly charge them.

Grand battery test

Every time I buy batteries, I have a lot of questions:

Are expensive batteries better than cheap ones?
Which of the batteries that cost the same is better to buy?
How much larger are lithium batteries than regular batteries?
How much capacity of saline batteries is less than that of alkaline?
Are batteries for digital devices different from ordinary ones?

To get answers to these questions, I decided to test all the "finger" (AA) and "little finger" (AAA) batteries that can be found in Moscow. I collected 58 types of AA batteries and 35 types of AAA. A total of 255 batteries were tested - 170 AA and 85 AAA.

To improve the accuracy of measurements, the battery analyzer does not use PWM - it creates a constant resistive load on the battery. The device can operate in different modes. Three main modes were used to test AA batteries:

Discharge with direct current 200 mA. Such a load is typical for electronic toys;
. Discharge with 1000 mA pulses (10 seconds load, 10 seconds pause). This load is typical for digital devices;
. Discharge with 2500 mA pulses (10 seconds load, 20 seconds pause). Such a load is typical for powerful digital devices - cameras, flashes.

In addition, four batteries were discharged with small currents of 50 and 100 mA.

Measurements were made when the batteries were discharged to a voltage of 0.7 V.

All test data are summarized in a table.
The discharge graph clearly shows how different types of batteries behave.

Discharging AA batteries with a current of 200 mA

The first five lines are salt batteries. It is clearly seen how much smaller their capacity is.
The last three lines are lithium batteries. They not only have a large capacity, but they also discharge differently: the voltage on them does not decrease almost to the very end, and then drops sharply. This is especially pronounced in the GP Lithium battery. In addition, lithium batteries can work in the cold.
Among the many similar alkaline batteries, two outsiders are clearly visible - Sony Platinum and Panasonic Alkaline and two leaders - Duracell Turbo Max and Ansmann X-Power. The remaining batteries differ in capacity by only 15%.

In the first diagram, AA batteries are sorted by capacity at a discharge current of 200 mA.

Duracell Turbo Max batteries do have a slightly higher capacity than all other alkaline batteries, but I came across one package of Duracell Turbo Max that was significantly worse than others. In terms of capacity, they corresponded to ordinary cheap batteries. They are labeled "Duracell Turbo Max BAD" in the table and graphs.

The diagram clearly shows that different batteries behave differently when discharged with large and small currents. For example Camelion Plus Alkaline gives more energy than Camelion Digi Alkaline at low current. But on the big one it's the other way around. As a rule, batteries designed for high currents indicate that they are designed for digital devices. At the same time, there are many universal batteries that work perfectly with any currents.

I averaged the amount of power that batteries put out at high and low currents and based on the results and the price of the batteries (which in some cases is only an approximation) I made a chart of the cost per watt-hour for all AA batteries.

All types of AAA batteries were discharged with a constant current of 200 mA. Some types of AAA batteries were subjected to a second test - a discharge with a current of 1000 mA in the "constant resistance" mode (the current decreased as the discharge progressed). This mode emulates the operation of batteries in a flashlight.

In AAA format, Duracell Turbo Max turned out to be far from the best alkaline battery. Many cheap batteries (eg Ikea, Navigator, aro, FlexPower) had a larger capacity.

Technical conclusions:

Most alkaline batteries differ in capacity by only 15%;
. Lithium batteries have 1.5-3 times (depending on the load current) greater capacity than alkaline ones;
. Unlike alkaline batteries, the voltage on lithium batteries almost does not decrease during the discharge process;
. Salt batteries are 3.5 times worse than alkaline batteries at low currents and cannot work at all at high ones;
. There are three types of alkaline batteries: universal, designed for low load currents and designed for high load currents. At the same time, universal ones are better than the other two at all currents.

Consumer Conclusions:

Salt batteries are not worth buying. Even in devices with the smallest consumption, alkaline (Alkaline) will last much longer due to their long shelf life;
. It is most profitable to buy batteries sold under the brands of Auchan and Ikea stores;
. In other stores, you can safely buy the cheapest alkaline batteries;
. From what is sold in grocery stores, the best choice is GP Super;
. Lithium batteries are expensive, but they are light, capacious and can work in the cold.

Grand testing of AA/AAA batteries

Many have asked for the same thorough testing of NiMh batteries. In four months, I tested 198 batteries (44 AA models and 35 AAA models).

Usually on the Lamptest.ru blog I talk about testing LED lamps, which consume 6-10 times less than traditional ones and can significantly save on electricity bills. Today I want to touch on another aspect of savings - the use of rechargeable batteries instead of batteries.

Batteries were charged using La Crosse BC-700 and Japcell BC-4001 chargers. Batteries with a capacity of more than 1500 mAh were charged with a current of 700-800 mA, batteries of a smaller capacity with a current of 500-600 mA.

To determine the capacity, the batteries were discharged by Oleg Artamonov's analyzer. Batteries with a capacity of more than 1500 mAh were discharged with currents of 500 mA and 2500 mA, batteries with a smaller capacity - with currents of 200 mA and 1000 mA.

Basically, two copies of the batteries of each model were tested. For comparison, I used the results of the worst battery of the pair, but if four batteries were tested, for comparison, I took the penultimate one in terms of capacity.

Let's start with the simplest - battery capacity at average currents of 500/200 mA. Of course, it is more correct to take into account the capacity in watt-hours, but all batteries have a capacity in milliamp-hours, so I will use them.

As can be seen from the test results, the maximum capacity of AA batteries is 2550 mAh. All batteries with beautiful numbers 2600, 2700, 2800 and 2850 mAh are just the fruit of marketers. Their real capacity is sometimes even less than that of batteries from the same manufacturers with more modest numbers. On some batteries with large capacity values ​​indicated, the minimum capacity is indicated in small print (for example, Ansmann 2700, Panasonic 2700, Maha Powerex 2700 have a minimum capacity value of 2500 mAh and their actual capacity is close to this value).
But at AAA everything is honest. The maximum indicated capacity is 1100 mAh and the actual capacity is close to this value.

Duracell 1300 batteries after the first charge-discharge cycle showed very poor results, but after several charge-discharge cycles they showed the results that I take into account.
One of the four Turnigy 2400 LSD batteries had a capacity 30% less than the rest. I'm guessing it's a marriage. Its result is not taken into account.
The two Camelion 2800 batteries had a capacity of 2270 mAh and 2610 mAh (13% difference). Although the best of the pair turned out to be the most capacious of all AA batteries, I am forced to use the data of the worst copy, because no one knows what copies may still be caught when buying.
Chinese batteries BTY AA 3000 and BTY AAA 1350 have such a low capacity that they only belong in the trash and I will not mention them in further tests.

Unlike batteries, batteries cannot be classified as good / bad simply by capacity, because there are batteries of different nominal capacities on sale. Let's see how the capacity of the tested batteries corresponds to the declared one. If the battery is indicated not only nominal, but also the minimum capacity, I will proceed from it. For comparison, data obtained during discharge with an average current of 500/200 mA are used.

The quality of the batteries can be judged by how the instances differ from each other.

For most batteries, instances differ by no more than 5%.

Unlike batteries, accumulators almost do not lose capacity at high discharge currents. I compared the capacity at discharge currents of 2500 mA and 500 ma for AA batteries with a capacity of 1500 mAh and 1000/200 mA for AAA batteries and AA batteries with a capacity of less than 1500 mAh.

Some batteries at high currents are capable of delivering even more energy than at small ones (for such batteries, the difference between the capacity at high and low current is more than 100%).

Half of all tested batteries are made using LSD (Low Self-Discharge) technology. These batteries are sold already charged. I measured their capacity immediately after unpacking without pre-charging.

On average, LSD batteries were 70% charged. Of course, the level of their charge depended not only on the quality of the batteries, but also on the time and conditions of their storage, and the date of manufacture is only on some batteries.

I tested all batteries a week and a month after charging. The results in a week can be seen in the general table, but the results in a month.

Surprisingly, the Navigator 2100 AA and GP 1000 AAA non-LSD batteries were among the best in terms of charge retention during the month. Most batteries (both LSD and non-LSD) retain 90% of their charge after a month.

I will give prices for batteries as of 11/1/2015. Wholesale - wholesale price in "Source Battery", RRP - recommended retail price, Mag - minimum prices in stores and online stores (mostly leftovers purchased at a lower exchange rate), $ and € - prices in dollars and euros in foreign online stores, RUB — prices in terms of the current exchange rate ($1=64 RUB, 1€=70.5 RUB). In shops hobbyking.com and ru.nkon.nl delivery is paid, the cost of the cheapest delivery when buying 12 batteries is included in the price in the table.

The first comparison is at the cost of 1000 mAh based on the RRP and prices in online stores, if the batteries are not sold in regular stores.

IKEA batteries are in the lead, followed by batteries from foreign online stores PKCELL and Turnigy. The most expensive based on recommended prices were Panasonic Eneloop.

Many people buy batteries in foreign online stores, so I made the second comparison at the prices of foreign online stores and the minimum prices that I managed to find in Russian stores.

IKEA is ahead of everyone here, Panasonic Eneloop are not so expensive if you buy them online, and Fujitsu, produced in the same factory using the same technology, is even cheaper.

For most batteries, manufacturers indicate 1000 charge-discharge cycles, some manufacturers do not indicate the number of cycles at all (Camelion, Turnigy, GP, Varta). Some batteries only have 500 guaranteed cycles (IKEA LADDA 2000 LSD, Energizer PreCharged 2400, Panasonic Eneloop Pro 2450 LSD, Fujitsu 2550 LSD, IKEA LADDA 750 LSD, Energizer PreCharged 800, Panasonic 750 LSD, Fujitsu 900 LSD, Panasonic Eneloop Pro 9 00LSD) .
For AA Panasonic Eneloop 1900 LSD, AAA Panasonic Eneloop 750 LSD, AA Fujitsu 1900 LSD, AAA Fujitsu 800 LSD manufacturers guarantee 2100 cycles.
The maximum number of cycles of 3000 is guaranteed for low capacity AA Panasonic Eneloop Lite 950 LSD and AAA Panasonic Eneloop Lite 550 LSD batteries.

1. The maximum achievable capacity for NiMh AA batteries is 2550 mAh, for AAA - 1060 mAh. All batteries that say 2600, 2700, 2800 mAh and more actually have a lower capacity.
2. All AA batteries of famous manufacturers from 950 mAh to 2450 mAh have a real capacity of at least 97% of the indicated one, all AAA batteries of famous manufacturers from 550 mAh to 1100 mAh have a real capacity of at least 94% of the indicated one.
3. NiMh batteries, unlike batteries, almost do not reduce the amount of energy output at high discharge currents.
4. For a month of storage, both conventional and LSD batteries lose 4-20% of their charge.
5. New LSD batteries are usually 70% charged.

I spent four months testing and three days writing this article. Hope you find it useful.

2015, Alexey Nadezhin

After removing the batteries from the packaging (blister), do not rush to put them in the charger in charging mode. It is better to insert new batteries into any suitable device and use until completely discharged. Only after they are completely discharged can they be fully charged.

I recommend "training" NiMH batteries at the very beginning of operation. For example, you can insert your brand new batteries into the TechnoLine BC-700 charger, photo on the right, and select the REFRESH mode (capacity recovery). Thus, you will use the maximum capacity of the battery, as well as significantly extend the life of the battery.

How much current should NiMH batteries be charged?

Why does a finger battery get very hot when charging?

Strong heating of the battery during charging indicates that a very high charge current is set, or that the internal resistance in this battery is too high, and the service life is coming to an end. To prolong the life of your batteries, do not charge them unnecessarily with high current, provide forced cooling of the batteries if passive cooling is not enough. High temperature during charging negatively affects the chemical composition of the electrolyte, and leads to premature failure of the battery.

How to determine the charging time of a finger battery?

Determining the battery charging time is quite simple - look at the battery case, the ideal parameters for charging a particular battery are indicated there. But it is better to use such chargers that automatically determine the charge time for a particular battery. For example, the same TechnoLine BC-700. This charger determines the optimal charge time for each battery, that is, each inserted battery is charged autonomously; the process of charging a set of 4 batteries will not be interrupted if one of them charges faster.

Do I need to remove the battery from the charger immediately after charging?

For example, when charging 4 batteries, one battery charges faster. Do I need to take it out of the charger? Answer: no, you do not need to immediately remove it from the charger. You can safely leave it in the memory until the process of charging all the inserted batteries is completed.

Why does one battery take longer to charge from one package?

Obviously this is due to the fact that this instance has a higher capacity than the rest. In my practice, this is extremely rare, more often you can encounter the opposite situation, when one copy is charging faster than the others. I advise you to quickly align this battery pack to avoid possible problems with equipment that uses an unbalanced kit.

What does it mean to align a battery pack?

This means the following:
First, you check (test), for example, 10 batteries for capacity. This can be done using analyzer chargers, which are described in detail. After you have a list of the received capacities of 10 batteries on hand, sort them according to the same (or approximately the same) capacity parameters. Thus, you should get at least two sets of batteries of different capacities, 4 pieces each.

How long should a NiMH battery last after being fully charged?

It depends on the type of battery, its capacity, maintenance / storage conditions and service life. For example, Duracell 2650mAh NiMH batteries will hold a useful charge for about a week (that is, charged and left on the shelf), after which they need to be recharged. But, for example, Sanyo Eneloop 2000mAh (LSD) will hold a useful charge for several years.

It is also important to properly maintain the battery in order to increase the storage time without recharging. For example, NiMH batteries need to be "trained" periodically, thereby restoring the working capacity.

What are LSD batteries?

LSD batteries (Low Self-Discharge) are such batteries that differ from other types of batteries by a low level of self-discharge. That is, after a full charge, these batteries are able to hold a useful charge for a long time (about 3 years).

What does "battery training" mean?

The term "battery training" is synonymous with the term "recovery of NiMH battery capacity". In common parlance, the term "acceleration of the battery" is also used, which is the same thing. These are cyclic discharge-charge stages of NiMH batteries that restore the lost battery capacity. Depending on the capacity of the battery, the state of the electrolyte, the charge / discharge current, there can be a lot of these cycles (discharge-charge), and they can also be different in duration.