新货到! Terkini!

全新Samsung电芯，导体内阻60毫奥以内（真实毫奥表测量结果），化学反应速度的寄生内阻在30毫奥以内，全新时充/放电总内阻不超过90毫奥，于3S2P电池组（10.8V/11.1V，5200mAH），3A放电时仅有小于0.4V即刻降压，性能决对优胜于一般的廉价电芯，即使是那些标榜着3000mAH廉价电芯。容量可高达2546mAH或9.33WHr @ 3.7V（平均电压）每枚电芯。容量都是实际测试，有图为证，决不夸大虚标。电芯由原厂分类，一致性良好，更换后效果佳，不满包换，只在亚替电池企业。09年9月产，长年累积的经验告诉我们，锂离子电芯即使没用，一年可以丧失高达200毫安时/电芯。

Samsung sel terbaru sampai, rintangan dalaman sel dalam 60miliOhm. Muatan sel boleh capai 2546mAH atau 9.33Whr setiap biji. Semua angka didapat daripada ujian komputer seperti yang ditunjukkan pada gambar di bawah, bukannya cakap cakap kosong. Sel telah digolongkan oleh kilang asas, mempunyai sifat sifat kimia yang cukup hampir sama, boleh mencapai keputusan yang bagus selepas menganti, tak puas boleh minta tukar, hanya dibawa kepada anda oleh Alternative Battery Enterprise. Sel-sel ini dibuat pada bulan sembilan tahun ini, mengikut pengalaman kami, Li-ion sel, walaupun tidak digunakan, boleh kehilangan muatan alir elektrik sehingga 200mAH untuk satu sel dalam satu tahun.


六芯电可达5092mAH或56Whr（9.33*6）。

测试条件：
充电：1.25安，4.2伏特/电芯
放电：1.5安，3.0伏特/电芯

6 sel boleh dapat muatan 5092mAH atau 56Whr (9.33*6)

Syarat Ujian:
Caj: 1.25A, 4.2V setiap sel
Nyacaj: 1.5A, 3V setiap sel

〉〉更多详情/Maklumat Lebih/More Details

8.4V Linear Charger

This is an custom-built order from one of my customer a few days back, his UMPC battery is unable to be charged by his notebook. After he have comfirmed that is the UMPC problem, not battery problem, he send it to me to make a custom charger for him. A picture is worth a thousand words.

Picture below: charging a 7.2V li-ion battery pack, the LED will go off when the battery is removed or the charging current is less than 70mA.

Technical Spec:
Type: Linear Series Regulation, Quick Charge Catagory
Maximum Charge Current: 1.1A(+/-5%)
Maximum Charge Voltage: 8.4V(+/-1%)
Input Voltage: 10V-12V
Input Current: 1A
Charging Speed: Reach 70% in 2 hours, 100% in 5 hours (for 2600mAH 7.2V pack)
Fully Charged Indicator: LED, lit up when charging

*No trickle charge mode built in, no suitable for battery that have been drained down to 0%
*This is not a recomended way to charge your battery, although there are built in protection in the pack.
*Not suitable for battery with capacity less than 1000mAH, as the charge pump in rate may larger than the chemical can accept, can result in battery overheat.

Controllable Current Sink/Source Device

Our lab new member, controllable current sink/source device, the picture below show a working prototype.

Technical Spec: -General-
Interface: Fully I2C controllable, seamlessly switch between source and sink
Input Voltage: 16-24V
Current Sense: Gound Side, 20miliOhm sense resistor

-Current Sink Section-
Type: Closed loop current sense, high error amplification gain, fast sinking current correction
Maximum Current Sink: > -4A
Minimum Current Sink: 0mA
Sink Current Stability: Within 5% variation of sink current
Resolution: ~50mA per increasement, up to maximum current sink/sources

-Current Source Section-
Type: Buck Topology, closed loop current sense, bootstrapped high side N-Channel drive
Maximum Current Source: >5A
Minimum Current Source: 0mA, first step is ~200mA
Regulation Stability: Within 5% of output current, variation less than 50mA
Resolution: ~50mA per increasement, up to maximum current sink/sources
Temperature Stability: N/A (not tested)
Bulk Source Efficiency: >90% at 50-60% duty cycle
Transient Response: N/A (not tested, but in the catogory of considered slow
Switching Frequency: 200KHz
Ripple Voltage: less than 1v

Laboratory equipment, suitable to charge/discharge smart battery, can work together with microcontroller through I2C to modify the output current according to the aplication need.

Extended Repairing Power

Now Alternative Battery able to repair more battery than ever! Sealed/unsealed, write protected, error flag, permanent error, aging record, we clear it all now!

With years of experiences in battery refill, Alternative Battery have manage to study the battery controller board, and develop multiple softwares, hardwares and chip programmer that override the chip security, include those proprietary chip with not documentation available on the internet, clear permanent error of your battery. Alternative Battery know how a battery work and how to fix it!

Common:
bq2040, bq2060, bq2083, bq2084, bq2085, bq20843, bq20847, bq20851, bq20853, bq20857 (Texas Instrument)

PS331, PS401 (Power Smart, Microchip)

*New bq20885, bq20886 (Sony), bq20889

Advanced:
bq20z70, bq20z75, bq20z80, bq20z90, bq20z95 (Texas Instrument)

Customized:
bq8011, bq8012, bq80201, bq8024, bq8030 (Sanyo and Sony), bq8050, bq8055
M37512, M37515, M37516(Create by MITSHUBISHI (Now Renesas or NEC), Design or use byPanasonic, Sony, LGC), M37517 not verified
MAX1780, MAX1781 (MAXIM), MAX1782
AS3XX (Dallas (Now MAXIM), Sanyo)

Netbook/UMPC:

bq27210(Asus Netbook), M37512(SONY UMPC)

All trademark is belong to their repective owners.

That included majority battery pack of various brand, Acer, Apple, Asus, Clevo, Compaq, Dell, HP, Hyundai, IBM, Lenovo, MSI, Quanta, Sony, Panasonic, Hitachi, Gateway, Toshiba, TwinHead and etc, specify your model and get to know if it can be repaired! Any inquiry please mail to mail.altbattery@gmail.com.

100% customer satisfaction, long run time, long lasting, or else have your money back in one months! 6 months limited warranty!

Real Specialist, Real Alternative!

*We pay you back if we fail to repair the battery with monitoring chip listed above!

IBM 60/61 series
Dell Latitude D410
XPS M1330


HP Compaq 2510p
And more...

Please check it out at mail.altbattery@gmail.com to know if your battery can be repaired!
All sort of battery that nobody else out there able to repair up to date, ALT realt most of it, up to 90% standard battery pack. We will reject battery that can not be repaired, so our success rate of repair your battery is up to 98%, every 100 customers, only 2 of them have to be disappointed. We won't let you disappointed alone, we will buy back the battery that fail to be repair from you for further investigation of how to repair it, so you get a small amount of cash which reduce your cost to buy a new unit.

BTP-B2J1

For many years of repairing those obsoleted battery, I can conclude that repairing a rechargable battery is not easy job, if one think it is easy, he is not going to go very far. Likewise all of the others carreer, to go into specialist, you need a lot of hardwork. Why? Because many battery pack is not really designed to be repacked easily.

Recently I have broken the hook of a battery, what is hook? Look at the picture below and you will find out. Who didn't expect a perfect work, but sometime all this mistake just occur. It is unavoidable, even machine can make mistake, not to say us. He say want some more disccount, but I say can not, I have given you both quality work and product, somemore discount I am losing my income, but you are welcome back to me if it broken again, then he accepted my sincere apology.

People is differ from machine, if it occur once, we able to figure out what is the problem, we will make correction. Yesterday I got another one of this unit, a parcel from Sabah. Everyday we wanna become better than yesterday, gonna tell ourself this way.

So this time I do it like this, as the picture above. Protect the fragile hook with some thick paper. This time it is open nicely. I say everything need experiece to make it right, agree?

Want more juice from your battery? No problem, upgrade it, refer to the first picture above, this battery is 4000mAH, get an 5200mAH (usually real capacity is ~5000mAH) at a very reasonable price, and experience a 26% extra run time!

No people report that there are serious side effect by upgrading it capacity yet, perhap it will exhibit different impedence under different frequency or have life span reduced, but overall it give more runtime when user need.

Nokia PC Suite

Recently I am begining to use this software, to reply the SMS from customer. It let us use the SMS service like email. The question come, you have to sit in front of a PC to use it, why don't us use email directly? The problem is the contacts may not be in front of a PC when the interuption is need to be made. If it need urgent action to be taken, email may be too slow for both side to establish real meaningful comunication. But some people just rushing most of the moment of their life, they won't have much patience to wait for email reply.

You know, we can put a lot of precise information into SMS, such as address, number and something else such as a promise, if we use mouth, there are no track of such promise can be found. There is however, SMS will comsume too much time for us to type on the tiny key pad of our hand phone. With the keyboard of PC, now we can type faster. But please note that who always sit in front of PC? Sometime, if any reply is thus meaningless, what is the point of replying? So be patient to waiting for the solution to come out!

bq2060

Most of the time, the primary IC of the battery won't have any hardware failure. But, luck is not always on one's side, sometime it do fail. That is why secondary protection can be found on most battery pack protection circuit.

Just a few days back, I get one pack work with chipset S8254AA (primary protection )+bq2060 gas gauging ic. 2060 is a very old chip, but it is very comman in those old days pack, where we see plenty of them before, but it is really rare that it can fail. I am thinking of taking it picture, but the pack have already been posted back to customer, have forgoten to do that.

After replacing the cells of the pack, the pack neither charging nor able to discharge, I am begining to worry and about to tell the customer that your battery fail to be repaired.

But after some while, I am begining to realize that that could occur only if two possible, 1. S8254AA is out of order. 2. S8254AA is not being enabled.*Note: It could also be power mosfet failure, but it never been before that power mosfet fail in original pack although it sometime fail on some third party pack. It could also be the problem of bq, but I have check it funcationality through software, all activity pass.

A little bit hard work, manage to trace out that the control pin of S8254AA is actually control by Charge FET Control(CFC) pin of the bq2060, and CFC is measured a 10Ohm to ground, which mean a shorted could occur there. The real circuit is a little bit more complicated that above one, the picture above is for conceptual purpose only.

Unsoldering the bq2060 and measure the CFC pin with respect to ground, guess what? It is really shorted. The NMOS junction inside the I/O have probabaly subjected to permanent break down already. That is what make the current flow meter measure an aprox -10mA eventhough the pack is under static condition.

Guess what? Just replace the fail bq with a working one, it live again! Fortunately the replaced chip have pretty much the same property as the fail one, not noticable diviation of voltage, current and temperature as the old one. It save some time to recalibrate those parameter to correct one.

Advanced Repair Service

1. Even the chip have problem! Alternative battery can replace it at hiding cost, which you do not even realise we have do extra work cause you won't be told this.

2. Looking for an new pack but have no luck? Realt it! Alternative battery ensure 100% customer satisfaction.

3. The most serious work on bringing you a working laptop battery that you could possibly found within Malaysia:

• Spot welded.



• Quality & hi-capacity cell.



• Battery will be fully charged.



• Fully discharged to ensure it will not stop working half way and it will sleep or cutoff after it reach end of discharge voltage.



• Overcharged tested to ensure the battery will cutoff when overcharged.

IBM T60 series battery

Note all the information below is given as is without any kind of guarantee, trust it at your own judgements. If you think that this article is not true and should be removed, please contact the writer to remove this (mail.altbattery@gmail.com).

Over a year back, the writer have see some IBM fans complain that their battery is disabled between 1 year to 2 years of usage, even it still last more than one hours before it fail. Actually, many branded battery only last less than 2 years nowaday, not just IBM.

The IT product become cheaper and cheaper over the years, silicon chip is one that can be done much more complicated but at the same surface area. But battery isn't one that advancing so quickly, reducing the cost can somehow related to reducing of the raw material usage like reduced Cobalt used, which in term will reduce the usable duration.

What the writer found out and assume that, the battery lock the power input and output to prevent it from overheat! The manufacturer have learn the lesson from history, if you want to use it till last juice, it is more tend to show a phenomenon of overheat after the cell lose balance in state of charge. They usually only give one year waranty to battery, promising customers within what they can do is better that promising customer something that is more risky and impossible.


The writer have try to discharge a T61 battery produced year 2008 which not more usable after it have been use 174cycle, which stay at near 100% but not functioning.

See it still manage to discharge 2436mAH (note, it do not hold 100% at the beginning, since it is start discharge at around 12.4V), it rise back to ~3.7V per cell after it reach end of discharge, cell 1,2 reach 3.2V, cells 3 reach 3.0V. So it is not manage to output most of the power it have. The right picture, that is what the curve of end of discharge a new cell look like. One thing the technician manage to notice, the cells is self-balanced if user let it rest some time before recharge it, there have not clear proof of this, but user can try this to pro-long their IBM battery life.

Purposely charge it a while (blue circle) to turn on the battery and allow it to discharge again, See the cell have different voltage 3.36V, 3.401V when discharging, but this time it is more balanced after it do self balancing.

See, another 355mAH discharge, this mean the cells is not in real empty, just that it impedence is too high to output all the energy it suppose to deliver. This time it reach lower end of discharge voltage than before since the cell is self balanced. But still green circle show that it it around 3V for cell 2,3, 3.225V for cell 1 (which mean it have slightly different capacity). This could be the reason why the battery lock it power output itself.

UPDATE: 04thSEPT09

Customer feedback, a picture worth a thousand words...

"Battery been discharged completely once and fully recharged. So far so good."

For those advanced notebook with many feature and more graphical power, 2 hours is really good enough. Some older notebook without so many power hungry feature can last 3 hours plus or more, don't worry.

UPDATE: 30thSEPT09
Lenovo X61 series also can be fixed now, no problem. 100% can be realt if ur battery still can be used. 90% above if can not used anymore.

Tips: Thermal Transfer prototype PCB

Objective: Homemade low cost PCB, tips for student that doing electronic project.
Required: LASER Printer, Matte Paper, Iron.

Honestly the writer have seen this method introduced on the internet many years ago. But this is the first attempt to make a PCB in this way. Hope others can learn some tips and basic skill from here.

If we request prototype PCB from the factory, charges can be decade Ringgit Malaysia, if someone need a few (but not up to a ton) in quantity, it is sufficient for us to buy a printer already.

This post is not intend to teach you how you can iron the pattern you want on a copper foiled board (as you can easilly get the information on the internet), but to show you it is reliable and workable.

The Matte Paper below is used for this experiment. It is a sample from the writer's friend. This is the key of success transfer. In the printer option choose 'card board' and 'Best Quality'.

The circuit board will look like the picture below after doing thermal iron transfer, the ESYINK Matte Paper work just great to transfer almost 100% of toner (carban powder) onto the circuit board.

Picture below: After etched with our favorite PCB etching chemical solution-Ferite Choride. It take about 2-3minutes for etching process to take away the unwanted copper from the circuit board. The key to fast etching is - use cheap PCB with thinner foil (if you are not dealing with power electronic), use stronger Ferite Choride solution with lesser water (water is a need! But not too much), and shaking the container use for etching .

Use fine sand paper to remove the coating.

After some messy drilling work.

Finally...

Okay, it is done! Enjoy your project.

Cell arrived!

Battery model 2600mAH have been discontinued about two weeks, kindly inform our valued customers that new stock have arrived, it is available again! High quality Samsung rank A battery cell at affordable price! Google is very kind to provide us this blogging service for free! To save google's space, I just use back the old picture (taken and uploaded at Frebruary), new stock cell look identical to the picture below. No sastify 100% money back within 1 month, 6 months limited warranty!

Gurantee up to minimum 100 cycles of charges and discharge in 3-4 cells battery pack (current discharge must be less than 1C, ~2.5A).
Minimum 200 cycles in 6-8 cells battery pack(current discharge must be less than 1C, ~5A).
More than minimum 200 cycles in 9-12cells battery pack(current discharge must be less than 1C, ~5A).,
Or with minimum 1 years of service life expected, up to 3 years maximum usable life!

Example 1: You battery is 6 cells 56Whr, can use 3 hours! Mean it draw around 1/3C current.

Battery Life Expectancy(min)= 200 cycles or 1 years
Battery Life Expectancy(max)= 500 cycles or 3 years

I will say maximum never occur, notebook using considered big current which unlikely to allow more cycles after certain amount of usage. Consumer may experience a slightly lose of capacity (example 0.01Whr ireversible lose) in every charge and discharge cycle.

All data is collected from customers feedback depending on battery pack type and judge by it property (some battery allow a maximum discharge current of 2C)!
-------------------------------------------
Samsung 2600mAH:
Best suit battery with 2600/5200/7800mAH, 2600 cell is widthly used in 56WHr battery.

Real capacity: ~2530mAH, ~9.3WHr

Test Condition: Charging constant current ~5/12C up to 4.2V, discharge ~15/26C down to 2.75V

Internal resistance: less than 60miliOhm including PTC inside(after make a rough measurement by mili-Ohmmeter)

Manufacture year 2008, new! (there are some so call Samsung 2600 but used on the global market)

Samsung 2400mAH:
Best suit battery with 2400/4800/7200mAH, 2400 cell is widthly used in 53WHr battery. Can also use in 56Whr battery pack but with reduced run time.

Real capacity: ~2330mAH, ~8.4WHr

Test Condition: Charging constant current ~5/12C up to 4.2V, discharge ~5/8C down to 2.75V

Internal resistance: less than 60miliOhm including PTC inside (Around 53 to 58)

Manufacture year 2008, new! (there are some so call Samsung 2400 but used on the global market)

Beside, others lower capacity also available, such as 2200mAH or 1800mAH, for budget users.

*Samsung and Samsung SDI and any other trandemark belong to their repective owners.

You may not know:
Why Are There No Volume Li-ion Manufacturers in the United States?

Sell 100MSample/s digital PC based oscilloscope

Dual channel 50MHz sampling per channel, maximum bandwidth up to 25MS/s. Single channel up to 100MHz sampling 4ns per div. Good for major simple circuit analysis and troubleshooting.

Just connect it to the PC USB port, you will get a up to 4ns per div probe.

Notebook is for ilustrastion purpose only, not included.



Detachable ground with crocodile clip. Normally not needed, because USB port is grounded. Ungounded reference can not be measured.

Detachable cap with a clipper, can click on wire, underneath is normal test probe.

Come with box, driver CD software, small ring for probe regconized and a small screw driver for compensated probe abjustment.

Mosfet gate drive voltage and it ground @50kHz (probe software in full mode). Red line is math subtraction function. This measurement is so call overshot, which we observed a disturbance at the rising corner. This is because there are potential induced between the ground of oscilloscope and the ground of power sources, due to the inductance presented in the wiring of high power path. If the oscilloscope probe is properly grounded (closer to switching ground), the overshot observed is minimum.

Sampling 1KHz, 2V p to p test signal (in simple window mode).

Interested please email me:

mail.altbattery@gmail.com (David)

Battery Techinician's nightmare

This battery is another one which have strange shape in design. After open the side cover, totally exhauted. Compare to it little brother (below), it is a few time too complicated to open it without cracking the housing and short circuit the cell inside.




Finally it is opened after one and half hours of all the way possible, it open! What a shame, just a waste of time to open it. Compare to writting this blog only less than 10minutes. In such a way will dead on hungry if only manage to do too few pieces of battery a day. Will anybody want to pay for the extra labor? If not, will considere not accept this battery for repair next time.

P/S: Software and tools is frequently upgraded to ensure able to repair most battery and newer battery on the market.

The dynamic info page, remaining page is my secret recipe which help me repair most faulty battery thus no show off here.

Sorry Note

Sometime we recieved this sorry note from courier company. Some company will make resend upon request (usually because their service is more expansive). While Poslaju will required us to collect at the post office ourself.

Unfortunately, my area (TSI) was assigned to a post office which is slightly far but not the closest post office located at Jalan Gombak. While many others courier company which I do not even know where they located, may be quite some distances, if that so, why we still need a courier company if we have to go far to collect the items ourself?(Unless the item come from other negeri)

Hopefully one day will come, where they have many goods to deliver for the same area, where we can have better way to comunicate with post office computer, so that we can decide which day they can deliver our goods.

4-Pin to 3-Pin CPU Fan

One of my low profile AMD system with original HSF unit run up to 70 degree Celsius at full loading with the default cooler provide by AMD. Note I do not overclock it, May be it is because the space inside low profile system is small and that is not good for air circulation, besides, there are only small fan at the back.

So two months ago, I went to shopping for better cooler, finally I decide to buy the ZALMAN CNPS8700LED full copper cooler. In fact, it left me no any other choice at All IT Hyper Market there, most cooler sell there is gigantic which definitely can not be installed into a low profile system. In fact, I can only say that this is the only option I can get there for my system. And so I quickly grab (grab? OK, purchase one) one.

With the CNPS8700LED full copper cooler, I am happy and go home to test it out. Unfortunately, after unpack the cooler then only I notice that the cooler fan is an old fashioned 3-pin fan without PWM fan speed controlling pin. This is a little bit annoying because it simply mean that the AMD Cool'n Quiet won't be quiet actually. Although at the box there, it written "ultra quiet" cooler, but the fact is the fan provided isn't really so quite at it full speed which I plug in the 3-pin fan directly onto the motherboard with 4 -pin socket.

To address this issue, ZALMAN fan actually come with a simple fan controller Fan Mate 2 which allow us to manually adjust the speed of the fan at a balance of performance and noisy level preferred.




But I just don't like it, who wanna frequently control the fan them-self  I want an automatic Cool'n Quiet but not Hot'n Quiet. The fan should be allowed to run at higher speed when the CPU is getting hotter!

Therefore I begin to spend some time to develop my own "4-Pin to 3-Pin CPU Fan connector", it is just a piece of cake which can be done in one day by just using some electronic spare part on my desk. Adding some delay circuit with potential-meter will delay the speed of PWM fire, therefore lowering the minimum RPM of the fan. The delay time will gradually reduces when the PWM pulse width increased, because less "off" time to charge up the capacitor use for storing charge for delay.

Now, the motherboard can freely adjust the fan speed itself, from 800RPM to 2150RPM itself according to the temperature and potential-meter position. At potential-meter fully clockwise, it will rotate at the range 800RPM to 2150RPM, at fully counter close wise  it will rotate at the range of 1700RPM to 2150RPM for my ZALMAN fan. Somehow, the speed controlling is not linearly act accordingly to temperature, but overall it give me satisfaction.


I have been using it for more than one month now and it seem still functioning well.Now my CPU running only about 44-48 degree Celsius at idle and a merely 56 to 62 degree Celsius at full loading for 1-2 hours.

Update: 07thJuly09

The schematic below is the circuit described use, it may not be the best, but it have serve me nearly half years now. I do not guarantee it will work, make it at your own risk.

The 470nF capacitor will delay the PWM for fire (turn on, in power electronic, like driving a SCR, we like to use the word fire, it is cool!), if C1 is too large in capacity, PWM will never off, the fan will gain peak voltage continuously. The inductor is an optional component, I use a 100uH one, it will provide more stable output, do not use a capacitor to smooth out the output, it will overheated, since the circuit is not calculated for a true buck regulator.

The UC3843 conveniently provide 5V for TTL logic interface, which eliminate the need for fixed voltage regulator like 7805, it is a very common low cost PWM ic, it also reduce the number of transistor use, so overall use of UC3843 is cost effective because I have purchase them in bulk! May be not all (from different manufacturer) UC3843 can use in this way, because it is not designed for such usage.

I know this is not a very good circuit, but overall it work just fine.

*L1 shoud be 100uH, 2N2907 is draw upside down!(collector and emitter is reversed!), sorry for that, please take caution.

If you have any inquiry regarding this article, please feel free to email me at mail.altbattery@gmail.com. Remember to put a title name: "To David, About PWM Fan."

Ok, thanks for reading, and if you have time, please take a look at the link: video games waste energy and contribute to global warming

What is the Voltage of Li-ion cell?

Peoples ask me, what is the Voltage of your Li-ion cell? Honestly, this can not be answer strict always if they want the precise answer. Unless they only need some idea.

Voltage per cell is depending on your application, basically most Li-ion operate in the Voltage range 4.2V down to 3V. For light load application, the manufacturer will label it as 3.7V per cell, for heavier load application, manufacturer will label it as 3.6V per cell, because the chemical response is not fast enough and generated heat, according to the law of conservation of energy, power lose as heat will result in less potential generated.

Due to chemical different, some cell are still great to charge up to 4.35V and some can discharge down to 2.75V and yet still have acceptably stable molecular structure.

The resistance of the cell is low, typical in few decade of mili-Ohm range, contribute by the conductor use to connect the electrode plate and the thermal cut off switch or fuses inside the cell. Unlike normal dry cell, the resistance of the Li-ion cell maintain constant along the entire life of the cell. But the impedance of the cell do will change. It even change at different potential level, that is why impedance tracker bq20Z90 have to trace the impedance of the cell along the discharging Voltage.

Every charge and discharge cycle will destroy some group of the molecular structure of the electrode use, and the damage is irreversible, in chemistry we call this process as oxidation even though there may not have oxigen take place. For example Ferum (iron) will become Ferum Oxide if contact with water. Ferum Oxide molecule do not have strong grid among each others.

More damage in electrode result in rising of impedance in the cell. Therefore, the potential generated by the cell will reduce, resulting in a lower average Voltage.

3.6V, 3.7V or even 3.8V is just a reference. It unable to tell us the true story doesn't mean the labeled Voltage lie to us. This is why all the measuring equipment come in.

If the battery pack manufacturer do not label their product by nominal specification but real approximation, we can actually judge the performance of the battery pack by look at the Voltage labeled. Example if it label 10.8V(3.6x3), it usually last less than 2 hours. If it label 11.1V(3.7x3), it usually will last more than 2hours. Again, this may not be the problem of their battery, but it reflect that your notebook consume more power if the battery label 10.8V.

bq20Z90

I have heard of this battery gas gauge ic long ago, worrying if it able to be reused.


Finally I get the battery that using bq20Z90 from one of my customer on the last Friday.

The battery do not report correct capacity after I replace the cell inside, even after I charge and discharge it a few time after replace the cells inside.

After 2 days of effort, finally I figure out how to realt the battery properly.


To repair a bq20z90 battery with impedance track:

1. Save a copy of old data flash contain for back up.


2. Update the Qmax, Qcell0-3 field.


3. Restore the Ra Impedance table with default value. The default value can be found on Texas Instrument website.


4. Issue an command (0x0021 to MA) to enable Impedance Tracking.


5. Fully charge the battery. (Onward can be done by customer them-self)


6. Let the battery rest for 2 hours to make a relaxed voltage to less than dv/dt 4microV/s.


7. Discharged the battery to end of discharge. (This will update the impedance table)
   


8. Let the battery rest for 5 hours, 5-8 can be repeated for max accuracy.


9. That will produce a "golden pack" data-flash value for max accuracy for the same type of circuit with same cell. Save the "golden pack image" after the Qmax have been updated.
   

The image can be use to load into the next battery (same battery) where same cell use to replace. This will make the circuit calculate the capacity instantly base on the golden pack data. But, cell will degrade as time passing, but the change is not significant I think.

One important things is, the ic can be optimized for different chemistry, the cells I use have the chemical ID 109 (can use command 0x08 to get the info) .

After instruct an enable IT command, the VOK and QEN flag will be set, to allow factory initial learning.

I found that RA_cell_4 table of subclass 91 will not update, because this is a 3 cell in series battery, only 3 group of cells. So subclass 91 is actually the default impedance value. The value for cell 0-2 will update as the battery is discharging for offset 00 to 31 gradually. So I copy the value in the subclass 91 into the subclass 88, 89, 90, and 95 into 94,93,92, this save my time if compare to key in them one by one.

I also note that it will also take the conductor impedance into account, because cell 0 have higher impedance due to the fact it is the far from the circuit, therefore conductor is longer from cell to circuit, thus measure a higher impedance value. The maximum capacity will follow the lowest capacity cells, which is obviously is cell 0, because it measure a higher impedance by the IC.


After fully discharges the battery, I get the Ra table with above value but not yet learn a new Qmax. But the reported "Fully Charged Capacity" show that the Samsung 5200mAH battery group have a 50++mAH capacity after fully discharge. To save time, I discharge it at around 0.6C current, which is 3A, larger then the notebook need I guess, it sustaining for 103minutes. But it do not learn a new capacity Qmax.

The very basic condition for the Qmax to update as find in SLUU264:

• The temperature must be in the range of 10-40degree ceicius.


• Capacity change between rest is must larger than 37%.


• The voltage can not inside the range 3.737V to 3.8V for Chemistry ID 100.

That mean you do not need to do a fully discharge to make it learn a new capacity. After the capacity updated, the Update Status byte will become 06.

That is all, the battery will live again. Like the time you just get the notebook.

P/S: bq20z90 is definitely the best gas gauge IC for notebook battery that I even seen. The capacity reported is amazingly accurate!

Update:
After let the fully discharged battery rest for more than 5 hours, it learn a new capacity, and set the GasGauging.State.UpdateStatus (SubClassID82,Offset12) to 6. Cell_m_Ra_Flag MSB to 00 (note SubClass 91 do not update, because there are only 3 series cells, the table is not being use) and MaxError to 1%. Job done! My customer will be very happy with his 'new' battery soon. One thing interesting, cell0 have biggest capacity, I mention it should be the one which show lowest capacity before. I also no understand why is that happen.

SubClass 82 offset 8-9 show 0x1476 as in the picture above, this probably mean the battery I put in have 5238mAH capacity, but the controller circuit will "reserved" some capacity, around 200mAH, because deeply discharge can damage the cell faster. I notice it stop discharge at around 3.3V per cells, while in the battery data sheet, it show the cells I use can be discharged to 2.75V (because of the material use, LiCoO2/Carbon6) without bringing significant degradation to cells.

-Written by David
-08/02/2009

Updated 31/03/2009:

Now I get another battery gas gauge to fix bq20z80, the way to fix it is identical to bq20z90!

Updated 28/09/09:

Ok, here it come, their little brother, bq20z70, also can be repaired, no problem.