Some knowledge about charging lithium-ion batteries on mobile phones

I .Basic concepts:

1, lithium ion battery nominal voltage 3.7 V(3.6 V), charging cut-off voltage 4.2 V(4.1 V, according to the brand of the core has a different design). (The lithium ion core specification is: lithium ion secondary battery)

2, charging requirements for lithium-ion batteries(GB/T182872000 specification): First, constant current charging, that is, the current is certain, and the battery voltage gradually increases with the charging process. When the battery end voltage reaches 4.2 V(4.1 V), the constant current charging is changed to constant voltage charging., That is, the voltage is certain. According to the saturation degree of the core, the current decreases gradually as the charging process continues. When it decreases to 0.01 C, the charging is considered to be terminated.

(C is a representation of the current controlled by the battery nominal capacity. For example, the battery is the capacity of 1000 mAh, 1C is the charging current 1000 mA, note that mA is not mAh, and 0.01 C is 10 mA. ) Of course, the standard representation is 0.01 C5A, which is simplified here.

3, why do you think 0.01 C is the end of the charge: This is stipulated by the national standard GB/T18287 -2000, is also discussed. In the past, everyone generally ended with 20mA. The standard YD/T998-1999 of the Ministry of Posts and Telecommunications also stipulated that no matter how large the battery capacity is, the stop current is 20mA. The 0.01 C stipulated by the national standard helps to charge more fully and is beneficial to the manufacturer's certification. In addition, the national standard stipulates that the charging time should not exceed 8 hours, that is, even if it has not reached 0.01 C, 8 hours is considered to be the end of the charging. (Batteries of no problem quality should reach 0.01 C within 8 hours. Batteries of poor quality are meaningless to wait.)

4, how to distinguish between the battery is 4.1 V or 4.2 V: Consumers can not be distinguished, depending on the core manufacturer's product specifications. Some brands of cores are 4.1 V and 4.2 V common, such as A&TB(Toshiba), domestic manufacturers are basically 4.2 V, but there are exceptions, such as Tianjin lishen is 4.1 V(but currently it is also 4.2 V).

5,What happens when the 4.1 V core is charged to 4.2 V: It will increase the battery capacity, feel good to use, and increase standby time, but it will shorten the battery's service life. For example, the original 500 times, reduced to 300 times. Similarly, overcharging the 4.2 V core will also reduce the life span. Lithium-ion core is very delicate.

6,Since there is a protective plate in the battery, can we rest assured: No, because the cut-off parameter of the protective plate is 4.35 V(this is still good, the difference is 4.4 to 4.5 V), the protective plate is to cope with the contingency, if each time Overcharge, The battery will decay quickly.

7,How much charging current is appropriate: In theory, the smaller the battery, the better. But you can't wait three days to charge a battery. The low rate of charging stipulated by the national standard is 0.2 C(arbitration charging system), and the above 1000mAh capacity battery is 200mA, so we can estimate that this battery can be filled for more than 5 hours. (capacity mAh = current mA × time H)

The National technical supervision department identified lithium capacity, which was charged at a high rate of 1C and discharged at a low rate of 0.2 C. The capacity value was calculated in time. The number of tests was 5 times, and 1 capacity reached the end of the test. (That is, there are 5 opportunities. If the first test is qualified, the next 4 are not done.) Before the test, there is allowed a pre-cycle, that is, charging to 4.2 V with a constant current of 1C, which stops without a subsequent constant pressure of 0.01 C. The process is not 14 hours.

8, how much lithium ion battery can withstand the charging current: manufacturers can be very high, but the national standard high doubling rate is set at 1C, also take the above battery as an example, can be filled in more than 1 hour. Can the battery withstand such a large charge current? For the current lithium ion core, it is small.

There is currently no national standard for chargers. The implementation is the Ministry of Posts and Telecommunications industry standard YD/T9981999/2, which stipulates that the current of chargers must not be greater than 1C.

9, how the life is stipulated: In short, it means that the battery after N times 1C charge, 1C discharge, the capacity dropped to 70 %, at this time N is the life span. It's not like 300 is still working, and 301 isn't working. The national standard stipulates a life span of not less than 300 times. When the conditions we use are not tested, the life span will be longer.

II .Type and quality of charger, suggestions for use.

1, direct, directly inserted in the kind of mobile phone, some people like to call Lvchong, we used to call "fire cattle." This charger is equipped with a mobile phone. The original quality is good. The highlight is that it is ready to be used. Therefore, the charging current design is relatively large(strictly speaking, the charging current controlled by the mobile phone), and the charging time is short. Some mobile phones have trickle-down power supply after full, some mobile phones are full of the end, waiting for the futile. Look at the above concept, you know, it's normal, and you don't have to wait 14 hours.

For the charging effect of direct charging, it is also necessary to look at the mobile phone, because the charging control circuit is on the mobile phone, and the cut-off voltage is somewhat discrete. I actually measured that the same batch of mobile phones of the same type is basically between 4.09 V and 4.21 V. That is, if 4.09 V is off, it is not full, not the ideal capacity, and it may be fuller for some time. But don't forget that even if there is a trickle-down power supply, like the difference between the charging voltage of 4.09 and 4.21, the trickle-down power supply current of the mobile phone has a certain degree of dispersion. If the power supply current is large, it becomes a charge., 10 hours, Battery is also damaged, I have encountered a lot of batteries on the cell phone charred phenomenon, original power also has, brand power also has. If the battery is recharged, causing leakage, etc., it may also damage the mobile phone. Therefore, if you really want to recharge, you should control it within 2 hours and not exceed 8 hours.

In my opinion, lithium electricity is delicate and full enough. Use a few hours less at a time but spend more than six months, and use a few hours more at a time but use less six months.

However, there are also problems with the original direct charge, we have encountered a number of mobile phone with a high direct charge failure rate phenomenon. Fortunately, the fault is no voltage, if it is high voltage, it looks good.

There are a lot of non-original cattle on the market. The quality is no problem. The quality is poor. You can imagine it because you are stuck on the 220V alternating current and the other end is on the mobile phone. So in my personal opinion, It is not recommended to use non-original cattle. (At least the original will be blamed for the accident)

2, seat fill, there are two slots, the front can be put mobile phones, the back of the battery, need to use with the fire cattle. The original seat is of good quality, and many have "intelligence". Some brands can basically perform a constant current constant pressure charging process, and there is a process of charging power after charging. Although some brands do not do constant current constant pressure process, but the current voltage and other parameter control is accurate, it is also good.

The so-called intelligence is actually very simple. For example, the MOTOROLA battery has a chip(read-only memory ROM) inside, solidifies some coding, and after the battery is inserted into the charger, the charger reads the encoding, and knows what kind of battery it is and performs the corresponding charging process. It was all arranged. (Different models, different capacities, different regions of supply, and even different brands of core, different codes),

In a simple analogy, I call one, you follow the first plan, I call two, you follow the second plan, I call nothing, or I call three, but did not make an agreement with you, refused to carry out. The phenomenon is that the red light of the charger is flashing and it can not be charged(on the mobile phone, non-recognized batteries are displayed). It is not everyone's imagination that there is a single chip CPU control.

"Intelligence" is also reflected in other aspects, that is, the battery's NTC (thermistor) and standard resistance. Different batteries are composed of different standard resistors and chargers to determine the charging current, and after the charging current is determined. According to different ambient temperatures, the thermistor and the charger form another loop to adjust the charging current. (Some batteries have only thermal resistance, some have only standard resistance, and some have two.)

For example, for a certain type of battery, the capacity of thin and thick electricity is different, and the optimal charging current should also be different. Therefore, the standard resistance of these two batteries is different, so that the charger "knows" how much charge current is given by thin electricity., How much charge current is given for the thick electricity. In fact, the initiative is still on the battery side, the charger and the battery constitute a circuit.

Similarly, when the charging temperature changes, the resistance of the thermistor changes, and the charger forms a loop to adjust the charging current, protect the battery, and avoid overheating.

Now you know why there is a line of hardware contact plates on the battery and in the battery tank.

Intelligence is "no more than that."

And, of course, you know what a proper battery should do, right? Sometimes can not rely on chargers, batteries do not do well, chargers do not play a role. At present, many domestic batteries have replaced NTC with ordinary resistors to reduce costs, lose the effect of current adjustment, and have unreasonable design selection. This is an exception. Press the table first. It makes sense to see it.

The trickle-down current of the original seat is generally accurate, but it is sufficient to recharge for 2 hours after the charger turns green. Or this principle, for lithium electricity, to reach the core of the capacity should be sufficient, more useless. It takes a lifetime to squeeze lithium, and the occasional 14 hours may not damage the battery, but it's not a good habit.

That said, the original seat filled, said the market on the brand seat filled.

To be sure, none of the brand's charging processes on the market are strictly followed: constant current, constant pressure charging process(please tell me, I will buy). They can be roughly divided into several categories:

A, constant pressure, not trickle-down power supply: the battery recharging 4.2 V is the end, encountered such a seat fill, you wait 14 hours to deceive yourself. Although it was 4.2 V, it was already closed. There was no trickling process and there was no fullness.

In order to fill up, some designs have been damaged, the cut-off voltage has been changed to 4.25 V or more, and some people have designed to wait for the battery's protection plate to stop. The battery is full and you will be satisfied with it, but your battery life has been reduced. With this charger is overcharged, do not have to wait 14 hours also very good use.

B, constant pressure, use a fixed trickle-down power supply: The design of the conscience is an improvement over the above, charging to 4.2 V, using a fixed resistance to "leak" some current out, this trickle-down flow is fixed, plug in the battery there, Never stop. According to my measurements, it is usually about 30 to 50 mA. With this charger, when the green light is just not full, it is ideal to continue to recharge for about 2 hours, but the trickle-down is too large, and it is not good for the battery to continue charging for 14 hours.

C, constant pressure, the so-called smart pulse type: the battery is recharged to 4.2 V and then charged with a pulse current. This is the so-called high-end type, the design idea is good, but unfortunately the product is not competitive, the consistency is not good, that is, you buy may be good or bad. The downside of my measurement is that the pulse current is too much 50 to 100 mA, and the pulse is too dense, which is equivalent to charging. And expensive, so it's better to use B.

It is worth noting that some seats are designed to pursue the rapid effect of tamarind, and the charging current is high, close to 1C. For this seat, although it does not violate industry standards, However, it can not be understood by the concept of "small current filling". However, I do not recommend the use of such a seat charge.

The above is only a summary, and in order to pursue the "charging effect", engage in "overcharging and toppling power", "overcharging and pulse", and "fast adding and filling power". What they need is to leave a good impression on the user. When the user's battery fails, they will not blame the charger. At most, they will say: broken batteries, only use half a year!

Simple way to select seat filling:

Physical appearance and other aspects do not say, only electricity.

Select a seat fill, it is best to have a digital multi-meter, insert the empty battery into the charge, string into the multi-meter charging current, in the range of 250 to 350 mA is more appropriate, when the charger turns green, immediately take down the battery voltage, 4.15 Between 4.20 and 4.20 are relatively normal, After the green light is turned, the multi-meter is connected to observe the current, which is more suitable in the range of 30 to 50 mA. If you can choose such a domestic seat, you can use it. Why spend money to buy the original? Of course I mean the standard, qualified products in China.

It should be noted that:

The brand seat is basically unintelligent. That row of hardware contact pieces, except for the positive and negative poles, the rest is for you to look at(individual contacts with a thermistor are useful). But to understand the original seat filled with intelligent implementation methods, intelligence is not too mysterious too pursue.

(Now you know why some of the batteries mentioned above simplify the material? )

The product parameters have a certain degree of discreteness. Some brands have more than 4.2 V for charging, but as long as they do not exceed 4.25 V, they are allowed to have certain errors and have an impact on the battery, but they have little effect. (I measured the MOTOROLA original, with a maximum of 4.23 V)

III. Travel charges

When I say travel charge, I mean put a battery on it and plug it directly into the AC power supply. Don't confuse it with a fire cow that charges it directly into the phone.

The travel charge is characterized by its ease of use and the need not to prepare two things like a seat charge. Even if something goes wrong, it won't hurt the phone.

Travel charge simply means that the part of the battery charge of the fire cow and the seat is combined into one. The early travel recharge part was just a simple capacitor buck circuit that was prone to failure and unsafe. The current travel charge is basically a switch power supply, and the stability is good(of course, look at the brand). I randomly tested and tested five GD93 travel charges. Three days and three nights were inserted on the AC power supply. The battery was full and replaced. There was no problem with continuous long work. Of course, just because I don't have a problem here doesn't mean you won't have a problem. Users should take the trip out of AC after charging.

Some travel is marked with intelligence, CPU control, that is the factory's business, do not believe.

According to the selection of a few points to choose travel charge, there is no intelligence and what is the relationship? Domestic ones are also very good. Of course I mean the standard, qualified products in China.

I don't want to talk anymore. Charger is really a variety of, I have not included the imitation of the original, unqualified. Different products, different brands, different periods, different situations, everyone's concept can not be fixed.

In particular, the millions of substandard chargers on the market each month are actually in the hands of consumers. These chargers are extremely vulnerable to battery damage, such as charging for 14 hours.

My suggestion is: for the original straight, full plus 2 hours; For domestic direct charge, do not use; For the original seat, it is casual(but it can not be too casual); For domestic seats, it is full of 2 hours, and for domestic travel, it is full of 1 hour. Domestic production refers to qualified products that meet the standards. The above is just a suggestion. It may not be very accurate, but there is no need to charge for 14 hours. Even if the new battery, as long as it is lithium, there is no so-called "activation" concept, which is also said.

How do I charge?

I am: find a charger that can overcharge, recharge the battery above 4.25 V, very easy to use, extend a lot of time. But my battery core is broken, and I'm looking for standby time, not battery life. What about you?

The page contains the contents of the machine translation.