Rebuilding Battery Pack-L09S6Y02 Of LENOVO Laptop Model V570
This battery pack belonged to the laptop given to me by my son. When it started showing low battery warnings and stopped switching on, I knew that time had come for me to take action. I took out the battery pack from behind sliding out the two stoppers. Then applied petrol on the sides where the top and bottom covers were glued together.
Then pried the cover open by working the way from one end to the other. Let us have a look at the inside and how the cells are interconnected:
Six cells with two in parallel are connected together in series. So each set will give 3.7V with higher amperes. There were four tappings from the cells that go to the control board; LP1, LP3, LP4 & LP5. Unfortunately I forgot to click the board and its IC numbers! LP5 is the negative point, LP4 is from the next set of two cells, LP3 is from the next set and LP1 is the positive point. I separated the cells and measured every one of them and found that except two cells, rest was ok. I kept all the cells for charging separately in single cell chargers and checked again after the charging was complete. Then all the cells showed around 3.9V.
Then checked them with a torch bulb load. Two cells drained quickly showing that they were the culprits. Anyhow, we need to replace all the six cells together at a time and combining them with other brands (Incidentally, there were no markings on the cells!) is not at all advisable. The unchanged cells would soon fail one after the other sooner or later. I fetched 2600mA Foxpro cells which were definitely better rated. I drew a crude sketch on the table with sketch pen to know how the cells were connected with the numbers of the connectors:
What you see in the second picture above is the new cells and spot welding materials that I bought for handling such jobs. I have already covered about the spot welding machine in my previous articles and therefore I am skipping it here.
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Since the two cells are separated by a partition in the box, we need to take care that the fresh spot welding of tin sheet is done with the gap for it. First I removed all the four connectors from the board. Kept two cells in its compartment with the partition occupying the middle. Then spot welded LP5 to the negative sides of two cells. Then inverted the cells and spot welded the positive sides. Kept next set of two cells together bound by rubber bands, in parallel with the first two and welded the other ends to the negative points. Then bent it and placed it in the compartment. Thus four cells were in place with LP4. Welded the positive sides of the two cells and repeated the same for the next set of two cells and placed it in the compartment, completing the LP3 connection. Lifted the positive ends of the third pair of cells and welded them to complete the LP1 connection. After checking and confirming that there were no man made mistakes, soldered the four connectors back to the control board. Pressed down the cells and control board very well and put the top cover. Aligned the connector properly and fit it tightly in its slot. I did not apply any glue in the covers to bond it together, as I might have to open it in case it was found not suitable and rejected by the Laptop battery manager, like what our body does when alien things are implanted! (LOL) Sometimes current mismatch would create such problems. After fitting the battery in the laptop, when I switched on, the battery indicating icon showed charging four times and then displayed “0% plugged in, not charging.” I knew that the Battery Manager is objecting to accepting the new set of batteries. I combed the web for solutions and one solution was to select device manager-batteriesMicrosoft ACPI-Compliant Control Method Battery, then try updating the driver, which I did.
But this did not solve the problem. Next step suggested was to uninstall the ACPI-Compliant Control and shut down, wait for a few seconds and start the laptop again. Even after doing that the error was indicating same. Then when I happened to look at the battery indicator while typing this article, it showed full! I was pleasantly surprised and did not know what made it ok as I was concentrating on typing! Perhaps the Manager got worried that ‘his’ adamant nature was getting exposed to international level, where experts are going to read it and therefore decided to accept the second ‘employee!’ (LOL)
Anyhow, now I can say that mission got accomplished with inflated satisfaction getting added to the collection. Here is the proof for my claim:
This article was prepared for you by Parasuraman Subramanian from India. He is 76 years old and has more than 30 years’ experience in handling antique equipment like Valve Radio, Amps, Reel Tape Recorders and currently studying latest tech-classes conducted by Kerala State Electronics Technicians’ Association. He has done graduation in BBA degree, private diploma in Radio Engineering and retired as MD of a USA company. Presently working as Consultant to Hospital and other institutions.
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corriette cyrille
June 20, 2026 at 6:08 pm
Wonderfully done sir. Thanks for sharing your expertise.
Albert van Bemmelen
June 20, 2026 at 7:06 pm
Your attempt to fix this original 2P6S Lenovo laptop battery pack was very brave! Although recognized by the laptop's battery manager this pack still may fail in working time when its total energy capacity now is too limited.
When cells are tested in most lithium-ion testers their internal milli-ohm value measured is a good indicator of their present condition. 4.2V is fully charged, but 3.9V of course is not. From experience I know that most new bought 18650 3.7V cells with 2600mAh marking when used in building battery packs are standard capacity. Sadly new made battery packs often fail because of the poor China made 3S and 4S (cell number) charger boards. The smd protection ic's on them are very sensitive to even just touching them. I had to throw several of those brand-new boards away after they immediately got destroyed just by touching them to feel if they got warm. Why I already completely stopped fixing laptop battery packs and also with building new large battery packs. One day your battery pack still works and charges splendidly but the next day its powering capacity is completely gone even when the output voltage still shows it is fully charged upto 12.6V but the energy it outputs is gone. Which is what happened when my diy made 5S_3P battery pack with 3d printed housing (with allupto almost 2800mAh 18650 cells) no longer was able to power my 32 inch television for over 2 hours or more when I used my 12V to 230VAC inverter. Why I later bought a much safer completely built 120Ah LiPoFe4 battery with integrated BMS. Also because LiPoFe4 is much safer than the questionable standard sold 3.7V-4.2V Lithium-ion cells. They have a bit lesser energy density but when subjected to hazardous events, such as collision or short-circuiting, they won't explode or catch fire, significantly reducing any chance of harm. Which can't be said of all the laying around 18650 li-ion cells I have collected at home.