Laptop battery pack cell replacement.

[Barto1361]

Hi everyone!
I'm relatively new on the forum, but I've been subscriber of Dave’s blog for about a year and reading this forum for few months now and I’m happy to finally join EEV forum officially!
So, the thing is my dad’s laptop battery died after steadily declining in capacity for about a year. Laptop is Lenovo SL510 and battery pack model is 42T4751. After taking off the cover I found 6 Li-On cells packed neatly and after tracing wires and connections, It seems that they are connected parallel in two's which as far as I know is standard type of connection in laptop batteries. I found out that cell was made by Sanyo and the model number is R1112 (specs). I can't seem to find exact model in Europe, so since I'm not that good with electronics I'll need help finding an alternative that would fit the specs and not make a little fire. Any help will be appreciated.

[Neilm]

These batteries are for OEM use only and are therefore not usually sold to non recognized battery manufacturers. This is due to the inherent dangers of working with Li-ion batteries.

The pack when designed would have been tested to many different standards, there are a couple from UL, the IEC standard (62136) and UN38.3 for moving the batteries. These involve some serious abuse to ensure that they are safe.

Neil

[sonicj]

search eBay for "18650 tabs"

look for cells with similar (or better) specs than the stock sanyo cell. Stay clear of the "trustfires" and "ultrafires". stick with sanyo, sony, panasonic, etc.
Capacity: >2150mAh
Charge Current >1.505A
Max Discharge Current >4.3A

This Sony would work: Link
Capacity: 2600mAh
Max. Charge Current : 2.6A
Max. Disharge Current : 5.2A

-sj

[SgtRock]

Dear Sonicj:

--Excellent sleuthing there, my good man. I was just speculating on whether I would be able to do this for a laptop battery. I will use this information the next chance I get, and I will remember to stick to the approved brands. Thanx.

“Before turning to those moral and mental aspects of the matter which present the greatest difficulties, let the inquirer begin by mastering more elementary problems.."
Sherlock Holmes 1887 -

Best Regards
Clear Ether

[PeterG]

 Before you spend $$$ on new cells, i would look very closely at the pcb inside the battery. It is common for Li-Ion packs to have a suicide chip that stops the battery from charging after about 1000 charges. This is to prevent them becoming unstable with old age.

I know IBM and Apple use such a setup.

Regards

[SgtRock]

Dear PeterG:

--A friend of mine had a huge Heathkit Stereo Amplifier (250 Watts Per Channel RMS, which I built for him), that he would run into clipping all the time, I mean, listening to Heavy Metal, who could tell, from distortion. Feh. He had an ear for clipping like the Ice Cream Man. I inspected and found that the Speaker Protection Relays had fried, so I wired around them, and told him to hold it down until the replacement parts arrived. Needless to say he next toasted the resistors and I do not know what all. I was not to pleased, so he sent the it back to Heathkit and for the price of a new kit they fixed it for him.

--My question is can one circumvent the control chip on these laptop PCBs, or is is unacceptably dangerous?

"Does not squirrel crack nuts on bough of oak tree."
Lao Fu 1410 1620

Best Regards
Clear Ether

[PeterG]

It is generally deemed "unacceptably dangerous". I spoke to a company that repacks batteries and they now refuse to repack Li-Ion packs for Laptops.

From what i have heard, it is simply easier and safer to buy a new pack for your laptop.

Regards

[vtl]

From what i have heard, it is simply easier and safer to buy a new pack for your laptop.

Also cheaper with the economies of scale of laptops. I love DIY but I don't understand why someone would bother butchering their laptop pack when you can simply buy a new one cheaper.

[Psi]

Be careful about the after market battery packs though. The cell they use can be pretty budget quality.

I got an extended lithium battery for my laptop and it works really well capacity wise, i get around 6.5 hours just sitting there with the lcd on half brightness.
However the battery has an awful self discharge rate. Two months in the laptop bag and its down to 50% charge.
A good quality lithium battery is like 3% self discharge per month.

[SgtRock]

Dear Vtl:

--People who have an interest in doing this, may not be quite as stupid or crazy as you imply. Leaving aside for the moment safety considerations (which I have not yet adequately researched), and with the understanding that I am merely speculating, and not advocating, allow me, please to get down, to cases.

1) A person is given an IBM Lenovo SL510 and a couple of battery packs that will not hold a charge. Might he not want to try, making one good battery pack out of two duds, for no money.

2)A person has a dud IBM Lenovo SL510 battery pack with one bad cell. Would he not perhaps be tempted to pay $12.00 (including shipping) for a single new  Sanyo cell as opposed to paying $50 (shipping included) for a new genuine replacement battery pack.

--I might add that I do not at the moment see anything inherently more dangerous in the procedure, provided you solder them up correctly, than what is being done with electric race car battery packs, and power tool battery packs, every day. But I am willing to be persuaded otherwise.

--I often have to fix things for people who have little or no money, for little or no money, so I always have my eye out for a fiddle that will make a repair affordable.

"Three weeks in the lab will save you a day in the library every time"
R. Stanley Williams 1951 -

Best Regards
Clear Ether

[PeterG]

I think the same applies for any multi-cell li-Ion battery.

You can see there is a limit to the number of recharges by carefully reading the manual for these devices. They once used to read "the Battery can be recharged over 1000 times." now days the li-ion based devices read "can be recharged 1000 times." You will note there is a difference in the wording of the battery life.

There is no way i would replace only 1 cell in an aging pack.

Regards

[sonicj]

i was soldering a high discharge 3 cell lipo last week when my helping hands slid somewhere they shouldn't have. luckily, the pack was discharged & the clips did not weld the circuit permanently closed! normally, i tape everything down to avoid this sort of incident, but i had already pulled up the tape thinking i was done, but decided to rework the last joint and got lazy/complacent. damn near crapped my pants! 
-sj

[damo]

I believe that when they manufacture the packs, they need to match the batteries (especially the parallel ones) for internal resistance (and another spec from memory, may be capacity). This is to prevent things like over charging a single cell in the pack and large discharges between cells due to variants in internal resistance. If you were to replace the individual batteries in the pack, you would need to do this as well (see below). I would not use cells from different used battery packs because the age of the batteries means their internal resistances will be different (and capacity ), again see below.

From above: Risk of fire with Li packs

Not saying don't do it, just beware

[amyk]

Depending on the battery management chip you may need to reset the charge counter on it and program in the capacities of the new batteries. The older ones are usually a bit more friendly but some new ones even require the firmware to be reloaded to discourage reuse. Datasheets and information are difficult to find for obvious reasons, but there are sites out there, you'll just need to search.

[Kozmyk]

The cost of replacement packs for older laptops can be prohibitively expensive i.e. more than the laptop is now worth.
I replaced the 18650s in my old Fujitsu-Siemens Amilo Pro pack.
I paid around £5.50/cell, I didn't go for the cheapest, around £3/cell. 8 cells £44
They wanted around £150 for a replacement pack.
The hardest part was opening the plastic case, lot's of fiddly work with a razor saw. 
Unfortunately, the charging circuit was either shot or deliberately nobbled as mentioned above.
I test charged the cells prior to assembly, using quite a fancy lipo charger - Hyperion, so I know it wasn't the cells at fault.
I've given up on the old V7010 as a portable device so now it's a mains powered bench PC running my Hantek DDS-3x25 signal generator using Mechatrommer's wonderful GOLTEK software.

Comparable Lenovo replacements are more common and much cheaper.
My main laptop is now a Lenovo T61  Running Linux. Yay!

[metalphreak]

They don't actually "solder" the tabs on either. They use some kind of arc/spot welding technique.

[kripton2035]

something like this : http://www.pittnerovi.com/jiri/hobby/electronics/welder/index.html
or this : http://ultrakeet.com.au/index.php?id=article&name=cdWelder_p2

[bfritz]

This is something I know a bit about, as I worked for a major PC manufacturer, designing battery packs, fuel gauging, and safety and charging circuitry.

During manufacture of the cells, they are matched.  Matching procedure varies depending on the cell manufacturer, but basically matches the impedance and voltage of the cells.  This is done so that when cells are welded in parallel, they will share current equally.  Replacing only one or two cells in a pack, or replacing with used cells with slightly different characteristics, leads to unequal current sharing or voltage mismatch, which can result in what is referred to in the industry as "Rapid Disassembly".  :-)

The Lenovo pack does contain a pack disabling device.  If the cells got too far from being voltage matched, or the circuit detected current flowing when the protection FET's were off, or overtemp conditions beyond certain limits, the device triggers.  Just shorting around the Permanent Failure (PF) device will not fix the pack.  The fuel gauge in the pack (Lenovo has one in all their notebook packs, as do Dell, HP, etc.) monitors this device and once it has blown it, or the secondary protection circuit has blown it, it sets a PF flag in a location of non-volatile memory.  Until that flag is cleared, the pack will refuse to enable the protection FET's, and will attempt to blow the fuse again, as it thinks it was unsuccessful in fully blowing the fuse, and will try again.  Lenovo also password protects the calibration and fuse bits in the fuel gauge and safety circuitry, so you would need to hack that before being able to reset the PF bit in non-volatile memory.

If you find the pack gives you some runtime, and will charge, then the cells are simply nearing end of life.  I would suggest buying a new pack from the manufacturer of your laptop.  Many of the aftermarket packs are not well made, and not worth what they charge, as you will be replacing them very soon.  The plastics are often ultrsonically welded shut, or glued.  Disassembly without destroying the plastics is quite difficult.  Even if that is accomplished, then you must weld new cells in place, or get cells with welded tabs attached and solder those in place.  There is typically very little extra room inside the plastics.  It is very easy if you don't know exactly what you are doing to allow a tab or high current strap to lay in contact with the shrink wrap over a cell, that then abrades with vibration, which then causes a fire!  A good short across multiple cells can deliver over a hundred amps... plenty to start a fire.  I do not recommend repair.

If you find the pack will not charge, and gives no runtime, then it is highly likely the PF fuse has been blown.  To repair the pack would require reprogramming the fuel gauge / safety part within the pack, and then replacing the PF fuse.  The fuses are quite difficult to come by.  I know of no distributor who carries them, and buying direct requires buys of the PF fuses in full reels.  After doing that you would still need to remedy the cause of the PF, which would may include replacing the safety FET's, and replacing the cells in the pack.

Repairing these packs is simply not practical.  It can be done if you are tenacious enough, but this must be tempered with the knowledge that you know what you are doing.  I know this stuff inside and out, and I wouldn't do it, as repair simply takes too much time. 

[saturation]

Great input, bfritz.  Something every laptop/netbook owner should know.  Currently the cost of replacement packs is far less than for me to DIY, so I've not even attempted to make DIY packs.

[amyk]

Lenovo also password protects the calibration and fuse bits in the fuel gauge and safety circuitry, so you would need to hack that before being able to reset the PF bit in non-volatile memory.

If you look in the right places on the internet, there is plenty of information about that Not necessarily in English though (see my point below).

Repairing these packs is simply not practical.  It can be done if you are tenacious enough, but this must be tempered with the knowledge that you know what you are doing.  I know this stuff inside and out, and I wouldn't do it, as repair simply takes too much time.

It depends on where you live. In some places (developing countries mainly) labor is cheap, and a couple of 18650s (and maybe a new chip) will cost far less than an official replacement.

[bfritz]

Lenovo also password protects the calibration and fuse bits in the fuel gauge and safety circuitry, so you would need to hack that before being able to reset the PF bit in non-volatile memory.

If you look in the right places on the internet, there is plenty of information about that Not necessarily in English though (see my point below).

I'd like to see that.  Where is such a location.  A link to a google translateable link and I should be able to discearn the info.  I ask, as the password scheme used would make a brute force method very difficult, and if anything has likely been social engineered.  I have the ability to figure out quickly if their password works, or not.  I have yet to see any of the manufacturers packs cracked, that were bothering to use a password.

Repairing these packs is simply not practical.  It can be done if you are tenacious enough, but this must be tempered with the knowledge that you know what you are doing.  I know this stuff inside and out, and I wouldn't do it, as repair simply takes too much time.

It depends on where you live. In some places (developing countries mainly) labor is cheap, and a couple of 18650s (and maybe a new chip) will cost far less than an official replacement.

The real question, is what happens if your house burns down, and the insurance company finds out you "fixed" the pack, and it was the source of the fire?  That would make such a "cheap fix" the most expensive fix of your lifetime!  Just not worth it...

[SgtRock]

Greetings EEVBees:

"The real question, is what happens if your house burns down, and the insurance company finds out you "fixed" the pack"

--Yes after a house fire kills your entire family, it could get even worse in a hurry. What if the Insurance Co. marks you down for piddly diddlies, and you encounter a devastating financial loss? What happens if the Insurance Co. finds out you bought a cheap One Hung Low battery pack, instead of an official Major PC manufacturer battery pack? Indeed what happens if the Insurance Company finds out you "fixed" your television which was connected to line power.

--If I were you, I would think twice about removing that mattress tag.

"I could see that, if not actually disgruntled, he was far from being gruntled."
P. G. Wodehouse 1881 1975

Best Regards
Clear Ether

[amyk]

Lenovo also password protects the calibration and fuse bits in the fuel gauge and safety circuitry, so you would need to hack that before being able to reset the PF bit in non-volatile memory.

If you look in the right places on the internet, there is plenty of information about that Not necessarily in English though (see my point below).

I'd like to see that.  Where is such a location.  A link to a google translateable link and I should be able to discearn the info.  I ask, as the password scheme used would make a brute force method very difficult, and if anything has likely been social engineered.  I have the ability to figure out quickly if their password works, or not.  I have yet to see any of the manufacturers packs cracked, that were bothering to use a password.

Due to the nature of the information, it tends to be spread out thinly and not easily found, but if you're determined enough it is posisble... I don't remember any specific sites, although here is one I just found:

http://batterygroup.vn/bgvn/forum.php

Repairing these packs is simply not practical.  It can be done if you are tenacious enough, but this must be tempered with the knowledge that you know what you are doing.  I know this stuff inside and out, and I wouldn't do it, as repair simply takes too much time.

It depends on where you live. In some places (developing countries mainly) labor is cheap, and a couple of 18650s (and maybe a new chip) will cost far less than an official replacement.

The real question, is what happens if your house burns down, and the insurance company finds out you "fixed" the pack, and it was the source of the fire?  That would make such a "cheap fix" the most expensive fix of your lifetime!  Just not worth it...
[/quote]Talking about risks, it would be interesting to compare the relative risks to other sources, like dying from a serious disease (especially in a developing country), or a car accident. I know that some guys over at candlepowerforums.com use completely unprotected(!) 18650s in flashlights and only a very small percentage of them have actually had any incident. We do hear about batteries exploding and catching fire, but compared to the number actually in use, I would say the percentage is miniscule - otherwise there would be a lot more news about it.

[SgtRock]

Dear Amryk:

--I checked out the site you provided, and indeed it seems to be a site concerned with Laptop Batteries, Laptop Battery Control Chips, and reprogramming of Control Chips. A couple of the chips mentioned, are even available from Digi-Key.

--The response to your statement about such sites was:

"Where is such a location.[?]  A link to a google translateable [sic] link and I should be able to discearn [sic] the info.".

--The rapid typing and the seemingly prosecutorial phraseology, gave me the feeling, that just possibly your credibility was being called into question. It was almost as if the questioner, instead of searching for the information himself, was indicating that the existence of this information was so unlikely that, there was no point in searching for it, and that your veracity would remain in question until, the unlikely event that, such a site was provided. If indeed such was the case, I think the link you provided has gone a long way towards establishing your bond fides.

--Now when someone indicates that in their opinion a certain practice is, impractical, imprudent, and unsafe, I am generally willing to accept the assertion and perhaps even agree with it. But, when they go on and on, and begin to get increasingly hostile, I get the feeling that once they have spoken, all discussion is supposed to cease. Feh.

--Even though I will probably never repack and reprogram a Laptop Battery, it is indeed good to know how to do it, where to get the information, and what to look out for, if one should need to.

--I know for a fact that people routinely repack and re-solder Lithium Ion batteries for power hand tools and RC cars every day, and yet I see few reports in "Catastrophic Battery Fire Weekly" magazine concerning this practice.

"Extraordinary claims require extraordinary evidence"
Carl Sagan 1934-1996

Chock-dee-na
Clear Ether

[bfritz]

Dear Amryk:

--I checked out the site you provided, and indeed it seems to be a site concerned with Laptop Batteries, Laptop Battery Control Chips, and reprogramming of Control Chips. A couple of the chips mentioned, are even available from Digi-Key.

--The response to your statement about such sites was:

"Where is such a location.[?]  A link to a google translateable [sic] link and I should be able to discearn [sic] the info.".

--The rapid typing and the seemingly prosecutorial phraseology, gave me the feeling, that just possibly your credibility was being called into question. It was almost as if the questioner, instead of searching for the information himself, was indicating that the existence of this information was so unlikely that, there was no point in searching for it, and that your veracity would remain in question until, the unlikely event that, such a site was provided. If indeed such was the case, I think the link you provided has gone a long way towards establishing your bond fides.

--Now when someone indicates that in their opinion a certain practice is, impractical, imprudent, and unsafe, I am generally willing to accept the assertion and perhaps even agree with it. But, when they go on and on, and begin to get increasingly hostile, I get the feeling that once they have spoken, all discussion is supposed to cease. Feh.

--Even though I will probably never repack and reprogram a Laptop Battery, it is indeed good to know how to do it, where to get the information, and what to look out for, if one should need to.

--I know for a fact that people routinely repack and re-solder Lithium Ion batteries for power hand tools and RC cars every day, and yet I see few reports in "Catastrophic Battery Fire Weekly" magazine concerning this practice.

"Extraordinary claims require extraordinary evidence"
Carl Sagan 1934-1996

Chock-dee-na
Clear Ether

Wow.  Are you that unhappy that you just Troll threads here, looking to try and start fights, where there are none?

I have yet to see how you have added anything to this thread.  The rest of us are getting along just fine, and working to learn something from one another.  I have not found places where information about the passwords for major pack manufacturers are available.  I do not find the passwords for the packs, at that very site either, but I am taking the time to look, as it is something I am interested in determining:  Are the existing safety measures broken, or are people just reverse engineering and creating packs with the existing parts in the marketplace.

As far as the comments about there not being any reports of fires or explosions of packs...

How many reports of house fires do you see daily?  I guess there is no need for smoke alarms then.  LOL

I know of at least two major recalls of battery packs by major computer manufacturers here in the US.  HP had a major recall, where the people I know in the industry believed the issue was a wire abrading and shorting out over time.  Even at their cost for the packs, this had to be in the millions of dollars.  I know Dell had a recall, where it was believed that small metal fragments from a cell winding machine were wound into the cell, and were causing punctures in the seperator.  Again, millions of dollars in cost to fix those concerns.  Perhaps you are too young to remember the several incidents with metallic lithium cells.  There was one fairly famous one where the battery pack in a mobile radio exploded and burned the face of someone in ASIA.  In the world today, if you are a corporation with deep pockets, having safety failures in the 0.01% area could put you out of business very quickly, but that certainly fits your small percentage that we don't need to worry about.  For a small business, they are often forced to just shut the doors.  I have seen this happen to several smaller battery pack manufacturers in ASIA.

An 18650 cell is capable of delivering currents of 100A into a good short.  It is quite easy to cause a short with these cells, and start a fire.  In my career I have performed abuse testing on hundreds of cells, and given feedback to manufacturers that has helped to reduce risks.  If you choose to ignore the risks and operate packs with no safety features in place, or choose not to abide by pack manufacturers best practices, I can only hope you don't experience first hand the failures that not only can, but do occur.

Go ahead and believe the risks are not real, or that you are immune.  Just remember that you were warned.