Lenovo X201T Laptop Battery Problems - Page 1
Forum section: electronics / repair

author: paul_g_787
author_rank: Frequent Contributor
timestamp: February 06, 2023, 09:08:08 pm
content: Hey.So I am having a problem with my battery on my laptop. A Lenovo X201T with i7 CPU 8GB RAM and 256GB SSD. I used to use Win 7 until 2015 but now use Linux Mint 20.3.The battery started not showing up any percentage in the task bar any more in about 2016 and would instantly shut off if I unplugged the AC because it always said 0%.So I stopped using the laptop but the battery appeared to charge still just fine and I always kept it topped up every month or two.So I got the laptop back out to use it again now and had the same problem.I opened up the battery and the C and D (I assume clock and data) wires had come detached from the BMS PCB.I re-soldered these wires and checked all the cells voltages, all about 3.6-2.9V. I topped them all up one at a time using a single cell BMS until they then all charged up to about 4.1-4.2V so looks good.The laptop battery now shows a make and model number so the data wires are working whereas before it did not show anything at all. But it still only says 0% despite me leaving it in the laptop on AC for a few days.So I decided to order a new battery. I installed it, it was at 0% for a few mins then started to charge now it shows 100%.However when I do not have the AC adapter plugged in the laptop will not work.I cannot turn it on unless on AC. If I unplug the AC while the laptop is running it shuts off even with a full charge.Any ideas how to fix this?

author: Runco990
author_rank: Frequent Contributor
timestamp: February 07, 2023, 03:12:24 am
content: Probably not much help, but I own about 20 different thinkpads, the 201T among them. One thing about thinkpads is that they are pretty well protected. There are various surface mount fuses on the main board. I have changed a few in my time.I'd at minimum start there, (ohm them out) but it's a picky job. Gotta take the entire thing apart. However, it sounds like you are at that point anyway, as there is no magic command that would fix it.Sometimes it is easier and pretty cheap to just swap out the main board. Had to do that once or twice. Love older thinkpads!

author: paul_g_787
author_rank: Frequent Contributor
timestamp: February 07, 2023, 12:39:48 pm
content: Quote from: Runco990 on February 07, 2023, 03:12:24 amThat's certainly a possibility that it could be a fuse.Just having a look at the troubleshooting manual and found the battery test page. (See image)I am only getting 13mV (milliVoilts) on the output terminals when testing with my multimeter. Perhaps my new battery is dead?It arrived at 0% charge.

author: cascador
author_rank: Contributor
timestamp: February 07, 2023, 07:50:23 pm
content: I once sent back a new "noname" battery because it did not keep the charge.I then bought an original battery, and I got the same problem.I finally find out that the power supply was working perfectly on AC mode, but for some reason it was not charging the battery.I just changed the power supply and all went well. Go figure....

author: paul_g_787
author_rank: Frequent Contributor
timestamp: February 07, 2023, 09:16:14 pm
content: Alright so I just tried meaduring the voltage on my original battery as per those instructions and I get 16.1V. Which is as expected as I just charged it fully.But the original battery is still not reporting percentage to the laptop. I expect an issue with the BMS which I will look into later.The replacement battery I have left on charge all day but still only 13mV output.I expect the cells have been over discharged due to being store for a long time and the BMS is switching off the output to protect the cells? Maybe? Just guessing.I have raised an RMA for the new battery. Will see what the seller says.

author: zilp
author_rank: Frequent Contributor
timestamp: February 08, 2023, 08:27:45 am
content: Note that the charge controllers in laptop batteries tend to do charge counting, not voltage measurement. As the controller hasn't seen any charge flowing into the battery, it'll report it as empty.If you are lucky, the controller will recalibrate if you do a full discharge/charge cycle or two. If you are unlucky, it won't allow increasing the "last full capacity" value.As a workaround, you can probably find the battery voltage somewhere in /proc/acpi/battery, and use that to create a rough battery charge state indication.Regardless, other than status reporting, the battery probably will work just fine if it outputs voltage at its terminals and the SBS I2C works, as discharging should just work if there is voltage, and charging as well as deep discharge control will still happen based on cell voltage, the charge counting normally is only used for status reporting/warning, and maybe for automatic suspend/hibernation before the battery runs empty--the I2C is really only required for the pack-controller to request charge voltage and current from the laptop.

author: Runco990
author_rank: Frequent Contributor
timestamp: February 10, 2023, 04:44:14 am
content: I have had a few lenovo batteries arrive completely dead. It sat too long, the seller knows it. Return it. The BMS has cut off.Many CANNOT be reset, as the parameters are stored in RAM. Once it cuts off, you cannot re-program it. Only the factory.Some batteries will read voltage if you measure them but have zero current.I have found that periodically charging them and keeping them at no more than 60 percent in STORAGE, they last the longest.Also, try the stand alone charger. They sometimes wake up a battery that the laptop won't.There was a post years ago on youtube on how to sometimes jump start a BMS that is in shut down. I don't know where it went, but that only worked for older, dumber batteries.When I worked for a repair place, I could often nurse up a dead battery using a bench power supply until the laptop would "see" it.I'd still suspect the batteries before the laptop. Lenovo's are quite robust.

author: paul_g_787
author_rank: Frequent Contributor
timestamp: May 15, 2023, 06:41:53 pm
content: Yes it was the battery. I managed to get a refund and another one from another seller, same make battery. This one has been working great.Will probably try and re-charge the cells from the faulty one and re-use them in some projects.