Introduction.

Lithium-ion battery.

So called

Internal resistance.

sag

Controller.

Charging process.
Not recommended

How to extend battery life?

It is precisely because of the slowed down processes that charging a cooled battery will be ineffective. Moreover, it causes him some harm. You should wait until the battery reaches room temperature. The energy properties of the battery will return to their original values.

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2011-02-06T15:36:09Z 2011-02-06T15:36:09Z

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Something about Li-ion, or why the battery drains quickly

- Introduction.
Li-ion battery is a type of chemical current source that is widely used in modern mobile technology. Currently, manufacturers have almost completely abandoned the use of other types of batteries in mobile phones, so it is extremely important to know how to properly use lithium power supplies. This article will outline the main features of the design and use of Li-ion batteries, as well as some practical tips.

Lithium-ion battery.
Lithium batteries are considered to be the elements with the highest energy density, but at the same time they are the most sensitive to usage and charging technology. This is especially true given the virtual impossibility of performing a capacity restoration operation - lithium batteries are not affected by the memory effect.
So called training-recovery cycles have little effect on the service life of a Li-ion battery, since oxidation processes that increase the internal resistance of the battery are irreversible. It should be noted that a lithium battery is much more susceptible to aging and, due to corrosion, irreversibly loses some of its capacity during storage. even in ideal warehouse conditions. Therefore, when purchasing a new Li-Ion battery, the buyer must clearly know its release date. Unfortunately, manufacturers often encode the battery production date in the serial number, making it difficult for us to find.
For a Li-Ion battery, a mode in which the cell phone is used occasionally is not recommended, due to the relatively low efficiency of the battery in this case, as well as the relatively short service life.

Internal resistance.
This is one of the main characteristics of the battery. The smaller it is, the better. Normally, for a Li-Ion battery, the internal resistance corresponds to 150-250 mOhm at a voltage of 3.6V.
Internal resistance (hereinafter referred to as IC), by and large, determines the performance of the battery. If, when working with a battery with a high VS, it is necessary to provide a large load current in short-term mode, which is typical for cell phones, then the output voltage of the battery will be sag due to the large drop in battery life on the aircraft. Since the current consumption of cell phones is pulsed, at peak moments of current consumption the battery voltage may drop to the lower limit of the supply voltage and the phone will report that the battery is low, despite the fact that it is still far from being completely discharged. Thus, the phone can fail the owner at the most crucial moment.
In addition, high BC causes serious charging losses, which results in excessive heating of the battery. Also, when charging a battery with a high VS, the voltage on its cell reaches the threshold faster, and the phone will report that charging is complete, but the battery will be undercharged.
There are appropriate methods that allow you to measure the BC of a battery, but they are often inaccessible to the average user. The most common method is to measure the voltage drop in the battery under constant load.

Controller.
Li-Ion batteries are equipped with a special controller circuit that monitors the cell voltage and turns off the battery output contacts when its voltage goes beyond acceptable limits.
Unfortunately, sometimes you come across non-original batteries whose manufacturer skimped on the controller. This can lead to dire consequences, including depressurization of the battery and explosion due to overheating and increased voltage on it.
I myself had to deal with a low-quality product in which a pseudo-controller was installed:

As you can see from the photo, all this electrical nonsense, into which they forgot to solder half of the parts, does not receive power at all - the positive terminal of the battery is not electrically connected to it in any way. Moreover, some terminals of the transistors are either not connected anywhere or are shorted. This completely eliminates any interference of the circuit in the life of the battery. It is not surprising that after some time of use the metal glass of the battery noticeably swelled.
The controllers do not allow charging a battery that has discharged to 2.5V or less. The fact is that in such a deeply discharged battery, irreversible processes of destruction of the electrochemical structure occur, and an attempt to charge this battery will lead to the release of lithium metal inside it. Lithium release often causes explosions.

Charging process.
A specialized microcircuit is responsible for the battery charging process, which combines current and voltage stabilizers, as well as a memory element in which information about the sequence and duration of the charging stages is recorded. Since most often a certain microcircuit is designed for a certain battery capacity, then Not recommended using a battery in the phone with a capacity different from the standard one for its own battery.
Simplified graph of the full charging process for a 750mAh Li-Ion battery:


The charging process according to this schedule can be divided into two stages:
1. Charge at constant power, constant current.
2. Charge at constant voltage.
Sometimes you can find “fast” chargers that, bypassing the second stage, charge the battery in one hour. However, with this method, the battery only gains about 70% of its capacity.
There are so-called “frogs” - chargers that charge the battery directly through its output contacts. Often they do not provide a program of charging stages, which has a negative effect on the cell. Frequent use of this charging method will greatly reduce battery life.
Contrary to popular belief, you can charge a lithium battery even if it is half-discharged; you do not have to wait until it is completely discharged, as was done for NiCd.

How to extend battery life?
When using lithium batteries, it is useful to follow these simple tips.

1. While charging, disconnect from the Internet (especially in the case of 3G or Wifi) and the usb cable.
Any connection affects the charge duration, an active connection is even more so since it causes the battery to warm up. With an increase in temperature for every 10 degrees, the reaction rate increases by 2-4 times ((c) Van't Hoff), in this case the process of self-discharge and current leakage in the battery increases by 2-4 times, it wears out faster.
With an active connection, the charging time may increase several times, and even then the full charge signal will not entirely correspond to the truth (temperature and charge time limitation on the part of the microcircuit). Based on this, charging while the phone is completely turned off reduces the processes destructive to the battery during charging by 4-8 times.

2. The battery not used for a long time should be kept charged.
Dropping the voltage below 2.5V renders the battery useless. The self-discharge current for a Li-Ion battery is 10% per month, without taking into account the energy spent on the controller.
However, in the case of long-term storage, all this does not matter, since, as stated above, the aging process also occurs spontaneously. The typical battery life is no more than 2 years.

3. Do not charge a battery that has just been exposed to freezing temperatures.
When cooling, the processes inside the battery slow down. Therefore, when actively using the phone, a premature message about complete discharge is possible, although there is still a reserve. The effect is similar to high internal resistance, but is reversible. Due to the slow chemical reaction, the battery simply does not have time to supply the required amount of energy, resulting in a voltage drop.
It is precisely because of the slowed down processes that charging a cooled battery will be ineffective. Moreover, it causes him some harm. You should wait until the battery reaches room temperature. The energy properties of the battery will return to their original values. ">

If stored for a long time and not subject to charging and discharging operating conditions, cell phone batteries become unusable. An attempt to restore the capacity of batteries by long-term charging or special charging and capacity restoration modes does not always lead to the desired result. Nickel-cadmium and nickel metal hydride batteries used in cellular communications have a “memory effect” compared to lithium-ion batteries, do not allow long-term connection to a charger, and require training cycles. Lithium-polymer batteries use a solid dry electrolyte made of polymer, the disadvantage is poor conductivity, the advantage is very small thickness, resistance to overcharging.

After prolonged use, the battery does not have sufficient capacity for operation, discharges quickly and takes a long time to charge.
Battery aging is caused by increased crystallization. Crystals have high resistance and reduce charge-discharge current. The use of pulse chargers with a control system and jet charging allows you to extend the battery life.

It is possible to discharge the battery with currents not exceeding the transmission standby mode currents of 150-200 mA, loading with large currents - the protection circuit will disconnect the battery from the load after 10-20 ms. after connection, the circuit is locked and the discharge current is reduced to almost zero; when the discharge circuit is closed again, the discharge current reappears. This is necessary to prevent the lithium-ion battery from exploding after the formation of lithium metal and the danger of depressurization.

When diagnosing a battery, the discharge current can be obtained in pulse mode with a certain pulse repetition rate, the so-called pulse discharge.
To determine the technical condition of a cell phone battery, it is necessary to load it with a pulsed discharge current.

This solution is also applicable for diagnosing alkaline and acid batteries of any capacity, it all depends on the power of the batteries and discharge circuits.

The internal resistance of cell phone batteries should not exceed 0.3 Ohm, a large value will not allow normal operation for a long time, the voltage decreases rapidly, and soon the screen goes dark with the transition to energy-saving storage mode. To recombine lithium ions in the battery after a full charge, it is recommended to rest the battery for 3-5 hours. The shape and time of the discharge pulse of the cell phone battery diagnostic device must repeat the shape of the battery load current in the digital signal transmission mode in the GSM standard - a pulse transmission current of 1.5 Amperes, a duration of 567 μs and a repetition rate of 4.61 ms. The current consumption during pauses is 200 mA. The lithium battery protection unit consists of two microcircuits, one operates in comparator mode, the second contains two serial field-effect transistors with built-in diodes connected in opposite positions with the following functions: protection against over-discharge (when the voltage on the battery during discharge is below the set level, delay in closing the field-effect transistor VT1 is 12 ms), protection against shorting the battery terminals (when the voltage on the field-effect transistors exceeds a certain threshold, transistor VT1 closes at a speed of 0.4 ms), protection against exceeding the permissible charging current (another charger - VT2 closes), charging severely discharged batteries (element voltage more than 1.5 Volts).

The schematic diagram of a device for diagnosing cell phone batteries (Fig. 1) consists of: a waiting pulse multivibrator on an analog timer DA1, with manual external start and setting the frequency of the generator, a discharge circuit on a bipolar transistor VT1 and an analog indicator of the capacity of the battery under study on a DA3 chip. The circuit diagram is powered from a network source through a DA4 voltage regulator.

In the initial state, at output 3 of timer DA1, the voltage level is close to zero, since at the initial moment of power supply at the input of the lower comparator, the voltage level is above 1/3 Un. The circuit can remain in this stable state for any length of time.

When you press the SB1 - “Start” button, a trigger pulse appears at input 2 DA1 in the form of a low voltage level, the lower comparator of the timer is triggered and the internal trigger switches, which will lead to the closure of the reset transistor at input 7DA1, capacitor C2 will begin to charge through resistors R3, R4, at this time, the 3DA1 output maintains a high voltage level. The generation of rectangular pulses will continue with time T1=1.1 C1 (R1+R2).

When the voltage on capacitor C2 reaches 2/3 Un, the upper comparator is triggered and resets the trigger, the internal reset transistor discharges capacitor C2 through resistor R5.

When the voltage on capacitor C1 reaches more than 1/3 Un, the timer will stop working.
The duration of a single pulse at the output 3DA1 T2 = 1.1C2 (R3 + R4) can be smoothly changed with a variable resistor R4.

Pin 5 of DA1 allows direct access to the divider point with a voltage level of 2/3 Un, which is the reference point for the operation of the upper comparator. Using this pin allows you to change this level to obtain modifications to the circuit. In this cell phone battery diagnostic device, this output is used to stabilize the measurement mode and correct the influence of external temperature. The voltage modification at pin 5DA1 is carried out using the DA2 microcircuit - an adjustable parallel voltage regulator and is used as a source of reference voltage - an adjustable zener diode. The stabilizer chip has its own protection devices against overload and high input voltage. The thermistor RK1 allows you to adjust changes in the technical condition of the battery taking into account an increase or decrease in external temperature.

When the voltage across the load R9 in the emitter circuit of the bipolar transistor VT1 increases, the parallel stabilizer opens at the control input 1DA2, the cathode-anode resistance decreases and the voltage at pin 5 of DA1 drops, the frequency at the output 3DA1 of the timer increases, which leads to a decrease in the voltage at the load R9. The purpose of transistor VT1 in the diagnostic circuit is to connect the load, discharge resistor R9 to battery GB1. The battery under test is connected to the collector circuit of the transistor; in addition to the load, the voltage and temperature control circuit, the negative feedback circuit RK1, R11, R10 and the battery capacity level control circuit R12, R13, R14 are connected to the emitter circuit.

The voltage of batteries of different designs is slightly different; adjustment can be made with resistor R11. The voltage drop across the load - resistor R9, when the transistor VT1 is opened by the next pulse of the generator, creates a voltage drop; the greater the battery capacity and the lower its internal resistance, the greater it is. From variable resistor R13 through resistor R14, the control voltage is supplied to the input amplifier of the five-channel timer DA3. LEDs are connected to the terminals of the comparator keys K1-K5. The increase in voltage at the 8DA3 input, after amplification, is fed to the internal signal voltage divider; the keys at the inputs of the internal comparator will open when this voltage is exceeded. The higher the signal level, the more keys will be opened. When the voltage at the 8DA3 input is 0.25 Volts, all LEDs light up.

The LEDs should be distributed in the following order: red, full discharge - HL1, orange HL2 - the battery capacity is minimal, green HL3,HL4 - charged at 50 -75 percent, blue HL5 -100%. When fully charged, the ZQ1 siren will sound.

Setting up the circuit diagram for diagnosing cell phone batteries begins with checking the operation of the generator on the DA1 timer; if there is no oscilloscope, the pulses at output 3 of the DA1 timer can be determined by the LED or with a voltmeter at a high level when the “Start” button is pressed.

Having connected a freshly charged cell phone battery in the correct polarity, use resistor R13 to set the HL5 LED to glow.

When diagnosing batteries with a service life of more than 6 months, the number of LEDs turned on will decrease. Reducing the voltage on the battery with high internal resistance will reduce the voltage drop across the discharge resistor R9. The battery being tested is connected to the diagnostic device using sharp tips of the test cords used from the testers.

The measurement time is set by resistor R1, the pulse repetition rate in the range of 400 -1000 Hz is set by resistor R4.

The LEDs are attached to the holes in the front panel of the case in an acceptable order. All radio components are small-sized and installed on a printed circuit board.

A network transformer for an output voltage of 2*9 volts 100mA is mounted in the housing separately from the printed circuit board. The mains power supply, in a portable version of using the device, can be replaced with a 9-volt “Krona” battery.

Literature:

1. V. Konovalov “Charging and recovery device for Ni-Ca batteries” Radio No. 3 / 2006 p. 53.
2. V. Konovalov “Meter R-in AB” Radiomir No. 8.2004. p.14.
3. V. Konovalov “Pulse diagnostics of batteries.” No. 7.2008 p.15
4. D.A. Khrustalev “Batteries”, Moscow 2003.
5. I.P. Shelestov “Useful diagrams for radio amateurs” book 5.
6. Microcircuits for protecting lithium batteries. Radio No. 8 2004 p. 49.
7. Small-sized network transformers. Radio No. 8/2004 p. 44.
8. I. Nechaev “Voltage stabilizers with KR142EN19A microcircuit.” Radio No. 6.2000 p.57.

List of radioelements

Designation	Type	Denomination	Quantity	Note	Shop	My notepad
DA1	Programmable timer and oscillator	TLC555M	1			To notepad
DA2	Voltage reference IC	TL431	1			To notepad
DA3	Chip	AN6884	1			To notepad
DA4	Linear regulator	LM7809	1			To notepad
VT1	Bipolar transistor	KT829A	1			To notepad
VD1	Diode	KD512B	1			To notepad
VD2	Diode assembly	F12C20C	1			To notepad
C1		47 µF	1			To notepad
C2	Capacitor	0.1 µF	1			To notepad
C3	Capacitor	0.01 µF	1			To notepad
C4	Capacitor	0.22	1			To notepad
C5, C7	Electrolytic capacitor	470 µF 16 V	2			To notepad
C6	Electrolytic capacitor	10 µF 16 V	1			To notepad
R1	Trimmer resistor	1 MOhm	1			To notepad
R2	Resistor	100 kOhm	1			To notepad
R3	Resistor	33 kOhm	1			To notepad
R4	Trimmer resistor	330 kOhm	1			To notepad
R5, R10	Resistor	510 Ohm	2			To notepad
R6, R8	Resistor	1.5 kOhm	2			To notepad
R7	Resistor	12 kOhm	1			To notepad
R9	Resistor	3 ohm	1	5 W		To notepad
R11	Variable resistor	2.2 kOhm	1			To notepad
R12, R15	Resistor	5.6 kOhm	2

How to increase battery life? Why does my smartphone discharge so quickly? We will check popular myths that you can find on the Internet and tell the whole truth about modern gadgets.

Myth: Charging at night reduces battery life

Should you charge your phone at night? Let's figure it out.

• This myth is based on the danger of overloading the battery. But this problem is not relevant for modern smartphones.
• Even old lithium-ion batteries very rarely overheat if they are connected to the charger for too long. Modern batteries, however, are smart enough to handle overnight charging without issue.
• Unfortunately, there is some truth to this myth: the battery actually loses its charging capacity if you leave it . But these losses are so minimal that you won't notice them.
• Hence, you don't need to worry if you want to charge your smartphone overnight. The consequences will be far from what owners of phones with old batteries feared.

Tip: The battery will last longer if it is constantly balanced between 40 and 80 percent charge.

Myth: Quitting apps increases battery life

Many smartphone owners believe that they can extend the battery life of their gadget if they close unused ones. But this is a myth, because modern mobile phones are designed for multitasking.

• For example, if you exit an app on iOS, it will be frozen. This means that the program will stop doing anything and will not consume energy.
• By completely shutting down an application, you delete its data from the gadget’s RAM. When you decide to open it again, the application will have to be re-downloaded into the smartphone's memory. And this process will require much more battery resources than reopening.

Tip: Don't quit the app if you'll be using it again soon.

• Instead of constantly closing apps, you can extend the battery life of your gadgets in other ways. For example, or background program updates.

Myth: Use only original chargers

It is logical that most manufacturers want you to use only original chargers. “Native” accessories are quite expensive, but it is a myth that they are better for the battery. Many gadgets can use other chargers, and we will prove why.

• Modern smartphone charging devices are standardized. As a rule, the recharge time from a “non-native” device is slightly longer, but this does not affect the battery’s performance.
• You can charge your smartphone with almost anything, but we do not recommend using only cheap accessories purchased from well-known Chinese sites.
• Third-party chargers are a budget alternative that can be safely used as long as they are certified and charge the battery to the required level.

Myth: Bluetooth, Wi-Fi, and location services drain your battery faster

Some applications drain your smartphone battery very quickly. But this does not apply to features like Bluetooth, Wi-Fi and location.

• Bluetooth and Wi-Fi don't drain your battery as quickly as many people think. When we tested smartphones, the activation of these functions on average reduced the total battery life of the gadget by only 30 minutes. Agree, these are minor losses if the smartphone works throughout the day.
• But before, everything was different: Bluetooth also used other modules, the operation of which required much more power than their modern counterparts. Progress does not stand still, and now these services do not consume so much energy.
• Turning off location tracking will not increase overall battery life. But if you don't use this feature, it's better to disable it.

Tip: Most energy is wasted on the display backlight. If you are not using your smartphone, turn off the screen. Reducing the display brightness will greatly save battery power.

Myth: Always fully discharge your battery before charging it

Many people think that the battery must always be completely discharged before it should be connected to the network. But we are ready to dispel this myth too.

• This rule was relevant in the times of nickel-cadmium or nickel-metal hydride. It was they who had the so-called “memory effect”, in which the total capacity of the battery decreases and it does not charge above a certain level.
• Today, smartphones only use lithium-ion or lithium-polymer batteries, which no longer have a “memory effect.” However, some manufacturers still recommend calibrating the battery if the gadget begins to discharge quickly or even turns off at a certain battery level.

Batteries for mobile devices - charging methods

The old lady bought a car, drove it some distance, and suddenly the engine stopped. The called technical support service stated that the gas had run out. A perplexed old woman is suing: during the sale, no one explained to her that the car still needs to be filled with gasoline...

So, the batteries need to be charged. This is their significant difference from batteries. But before we talk about chargers, let's briefly look at the basic methods of charging the most common types of batteries. It should be noted that the charging methods for nickel-based batteries are different from the charging methods for lithium-ion batteries. Therefore, when charging the latter, pay attention to which charger you insert them into. In other words, not every nickel-cadmium (NiCd) and nickel-metal hydride (NiMH) battery charger is suitable for charging lithium-ion (Li-ion) batteries.

A few words about terminology. Battery capacity is usually designated by the letter “C” (capacity). When they talk about a discharge equal to 1/10 C, this means a discharge with a current equal to a tenth of the nominal capacity of the battery. So, for example, for a battery with a capacity of 1000 mAh this will be a discharge current of 1000/10 = 100 mA. In theory, a 1000 mAh battery can deliver 1000 mA for one hour, 100 mA for 10 hours, or 10 mA for 100 hours. In practice, at high discharge current values ​​the rated capacity is never reached, and at low currents it is exceeded.

Similarly, when charging batteries, a value of 1/10 C means charging with a current numerically equal to a tenth of the declared battery capacity.

Charging methods for NiCd and NiMH batteries

Existing methods can be divided into 4 main groups:

• slow charge- direct current charge of 0.1 C or 0.2 C for approximately 15 or 6-8 hours, respectively.
• fast charge- charge with direct current equal to 1/3 C for about 3-5 hours.
• accelerated or delta V charge- a charge with an initial charge current equal to the nominal capacity of the battery, at which the voltage on the battery is constantly measured and the charge ends after the battery is fully charged. Charging time is approximately an hour and a half.
• reverse charge- pulse charging method, in which short discharge pulses are distributed between long charging pulses.

Let me make a reservation right away: this division is quite arbitrary and depends on the battery manufacturer. The approach to the issue of charging batteries is something like this: the company develops different types of batteries for different applications and sets recommendations and requirements for the most favorable charging methods for each type. As a result, batteries (single cells) that are identical in appearance (size) may require the use of different charging methods. This approach can be illustrated by the materials posted on and.

Slow charging method

With this method, several options are possible: charging with semi-constant current and charging with constant current.

When charging with semi-constant current, the initial current value is set to approximately 1/10 C. As charging continues, this value decreases. Charging time is approximately 15-16 hours. In practice, the method is implemented by charging through a current-setting resistor from a constant voltage source (see for NiCd batteries). A slow charge of 1/10 C is usually safe for any battery.

When charging with constant current, a current value of 1/10 C is maintained throughout the entire charging time. (Fig.1)

Figure 1. Slow charging method for NiCd and NiMH batteries

During charging, the voltage across the battery cell increases. Upon reaching full charge and when recharging, the voltage begins to decrease.

Reducing the charging time by 2-2.5 times is possible by increasing the current to 0.2 C, but it is necessary to limit the charging time to 6-8 hours.

Fast charge method

A type of slow charge is the fast charge method, which uses a charge current ranging from 0.3 to 1.0 C. But this can cause the battery to overheat, especially at charge currents close to 1 C. To avoid overheating and determine when the battery has finished charging , a thermal fuse and a temperature sensor are built into the latter. The temperature sensor is used to measure temperature, the change of which is considered as a criterion for stopping the charge. The fact is that when a full charge is reached, the temperature of the battery cells rises sharply. And when it rises by 10 degrees Celsius or more relative to the environment, the charge must be stopped, or switched to slow charge mode. With any charging method, if high charging currents are used, a safety timer is additionally required.

Delta V charge method

This is the best and, perhaps, the main method for quickly charging NiCd and NiMH batteries for cell phones. The essence of the method is to measure the change in voltage on the battery to determine (fix) the moment of full charge and the need to stop it.

If you measure the voltage at the battery terminals during direct current charging, you will notice that the voltage first slowly increases, and at the point of full charge it will decrease briefly. The magnitude of the decrease is small, approximately 15-30 mV per element for NiCd and 5-10 for NiMH, but is clearly pronounced. This small drop in voltage is taken as the criterion for stopping the charge. In addition, the delta V charging method is almost always accompanied by a temperature measurement, which provides an additional criterion for assessing the state of charge of the battery (and to be sure, chargers for large high-capacity batteries usually also have safety timers).

Figure 2. Delta V charging method for NiCd and NiMH batteries

Figure 2 shows a charge graph with a current of 1 C. After achieving a full charge, the charging current is reduced to 1/30 ... 1/50 C to compensate for the phenomenon of battery self-discharge.

There are electronic circuits designed specifically to implement the delta V charge method. For example MAX712 and MAX713. Implementing charging using this method is more difficult and expensive than others, but gives highly reproducible results. At the same time, it should be noted that in a battery with at least one bad element from a chain connected in series, the delta V charge method may not work and lead to the destruction of the remaining elements.

NiMH batteries have specific charging problems. Their delta V value is very small and is more difficult to detect than in the case of NiCd batteries. Therefore, NiMH cell phone batteries have temperature sensors as a backup to detect when they are fully charged.

Another problem with charging with this method is that when used in cars, electrical interference masks the delta V detection and phones mostly control charge based on temperature. This can damage the battery since the phone is always connected in the car and the engine starts and stops repeatedly. Each time the ignition is turned off for a few minutes and then turned back on, a new charge cycle is initiated.

Reverse charge method

The Cadex 7000 [ , ] and CASP/2000L(H) battery analyzers use reverse pulse charging methods, in which short discharge pulses are distributed among long charging pulses. It is believed that this charging method improves the recombination of gases generated during the charging process and allows charging with a higher current in less time. In addition, the active surface area of ​​the battery's working substance is restored, thereby eliminating the “memory effect”.

Figure 3 schematically shows the time diagram of the reverse charging method for NiCd and NiMH batteries, implemented in the Cadex 7000 analyzer. Number 1 indicates the load (discharge) pulse, and number 2 indicates the charging pulse.

Figure 3. Reverse charging method for NiCd and NiMH batteries

The magnitude of the reverse load pulse is determined as a percentage of the charge current in the range from 5 to 12%. The optimal value is 9%.

Charging method for lithium-ion (Li-ion) batteries

To charge Li-ion batteries, the “constant voltage / constant current” method is used, the essence of which is to limit the voltage on the battery. In this way it is similar to the lead acid (SLA) battery charging method. The main differences are that for Li-ion batteries there is a higher voltage per cell (nominal cell voltage 3.6 V versus 2 V for SLA), a tighter tolerance for this voltage (±0.05 V) and the absence of slow recharging the end of a full charge.

• maximum charge voltage 4.2 or 4.1 volts depending on the battery model;
• end of discharge voltage 3.0 volts;
• recommended charge current is 0.7 C, discharge (load) current is 1 C or less;
• if the battery voltage is less than 2.9 volts, then the recommended charge current is 0.1 C;
• a deep discharge can lead to damage to the battery (i.e. the general rule must be followed - Li-ion batteries like to be in a charged state rather than in a discharged state, and they can be charged at any time without waiting for a discharge);
• As the battery voltage approaches its maximum value, the charging current decreases. The end of the discharge should occur when the charging current decreases to (0.1 ... 0.07) C, depending on the battery model. After charging is complete, the charging current stops completely.
• temperature range when charging is from 0 to 45 degrees Celsius, when discharging from minus 10 to 60 degrees Celsius.

The above data may differ in one direction or another for batteries from other manufacturers.

While SLA batteries allow some flexibility in setting the charge stop voltage, for Li-ion batteries manufacturers are very strict in choosing this voltage. The charge termination voltage threshold for Li-ion batteries is 4.10 V or 4.20 V, installation tolerance for both types is ±0.05 V per cell. For newly developed Li-ion batteries, other values ​​of this voltage will likely be determined. Therefore, chargers for them must be adapted to the required charging voltage.

A higher voltage threshold provides a higher capacitance value, so it is in the manufacturer's best interest to select the highest possible voltage threshold without compromising safety. However, this threshold is affected by the temperature of the battery and is set low enough to allow elevated temperatures during charging.

In chargers and battery analyzers that allow you to change the value of this voltage threshold, its correct setting must be observed when servicing any Li-ion type batteries. However, most manufacturers do not indicate the type of Li-ion battery and the end-of-charge voltage. And, if the voltage is set incorrectly, a battery with a higher voltage will produce a lower capacity value, and a battery with a lower voltage will be slightly overcharged. At moderate temperatures there is no damage to batteries.

This is, as a rule, the reason that a battery charged, for example, in a “native” phone, lasts less or longer than the same battery charged in a desktop charger from an unknown manufacturer.

The increase in battery temperature during charging is insignificant (from 2 to 8 degrees depending on the type and manufacturer)

Consumer intervention with any Li-ion charger is not recommended.

Slow recharging at the end of the charge, characteristic of nickel-based batteries, is not used because the Li-ion battery does not tolerate overcharging. Slow charging can cause lithium metallization and lead to cell destruction. Instead, a short-term charge can be applied from time to time to compensate for the small self-discharge of the battery due to the small current consumption of the protective device.

Li-ion batteries contain several built-in protection devices: a fuse, a thermal fuse, and an internal control circuit that turns off the battery at the low and high points of discharge and charge voltage.

Precautionary measures: Never attempt to charge lithium batteries! Attempting to charge these batteries may cause an explosion and fire, which will release toxic substances and may cause equipment damage.

Security measures: If the lithium-ion battery ruptures, leaks electrolyte and gets on your skin or eyes, immediately rinse these areas with running water. If electrolyte gets into your eyes, rinse them with running water for 15 minutes and consult a doctor.

When writing this article, materials were used kindly provided by Mr. Isidor Buchmann, founder and head of the Canadian company Cadex Electronics Inc. [—Batteries for mobile devices and laptop computers. Battery analyzers.

Batteries for mobile devices. Device and main parameters.

Batteries for mobile devices - condition assessment.

Batteries for mobile devices - types, comparative characteristics.

Despite the rich functionality of modern smartphones, their autonomy, as a rule, leaves much to be desired.

Unlike old and legendary phone models (Nokia, Sony Ericsson, Motorola), today's gadgets require regular recharging. Since this procedure gradually drains the battery, you need to follow simple tips for charging phone batteries. This will help extend the life of the battery.

Use a quality charger

Each charger has a specific set of , which are calculated based on the characteristics of the device being charged and the battery. It is for this reason that manufacturers of modern smartphones recommend using an original power supply or.

This precaution will help protect your phone battery from overvoltage, since cheap power adapters are often unable to provide an acceptable level of current. Also, do not forget to pay attention to the appearance of the charger: a damaged cord and a loose plug may be a sign of equipment failure.

Don't let your phone drain completely

As you know, daily use of a mobile device gradually wears out its battery. Leaving the battery in low charge conditions for a long time is essential.

Despite the fact that developers of modern smartphones use controllers that prevent the battery from being completely depleted, it is not recommended to discharge it to below 10%. Also, do not let the device turn off automatically, causing even more wear and tear on the battery.

Maintain optimal temperature conditions

Ambient temperature conditions greatly affect battery performance, and this applies to both warm and cold climates. It's no secret that using a smartphone in the cold often leads to a very rapid loss of charge and battery capacity.

Places with elevated temperatures are considered more dangerous, especially if the phone is charging in such conditions. According to statistics, prolonged overheating of the battery, reaching 60 degrees Celsius, reduces its capacity by 25% within 1 year. It is recommended to keep the device away from heaters, direct sunlight and other heat sources.

Do not load your smartphone while charging

An increase in the internal temperature of the battery occurs not only due to the influence of external forces. Connecting a smartphone to a power source in the form of an outlet also causes it to heat up due to the targeted effect of electric current. To protect the battery from dangerous overheating, which can completely damage it, try to refrain from using a smartphone.

This is especially true for heavy applications and games that force the mobile processor to work at full capacity and generate additional heat.

Try not to leave your phone charging overnight

Like an excessively low battery level, its oversaturation can negatively affect the overall performance of the gadget. Despite the presence of the previously mentioned controllers that limit the flow of current to the device, you should not leave the phone charging overnight like this.

Prolonged exposure to a sufficiently high voltage can have a detrimental effect on the health of the battery and lead to an overall decrease in its capacity. It should be noted that this is relevant mainly for budget devices without the proper degree of protection.

By following our simple tips, you can extend the life of your smartphone battery. You should not adhere to these tips too strictly - any equipment becomes faulty over time. Typically, a phone's battery life is 3-4 years, but these periods can be changed in both directions.