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Gary Jensen
Gary Jensen,
Category: Laptop
Satisfied Customers: 54
Experience:  Functional Systems Administrator at Hill Air Force Base, OO-ALC/309SMXG
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Replaced 2 batteries on my think pad t41 there is no voltage

Customer Question

replaced 2 batteries on my think pad t41 there is no voltage on the pins. it seems to me that the bms should be reset
Submitted: 1 year ago.
Category: Laptop
Expert:  Russell H. replied 1 year ago.

Hi, thank you for contacting My name is Russell. I will do my best to provide the right answer to your question.

Which 2 batteries did you replace?

If rechargeable batteries, then you need to give them a period to recharge, of course.

Did you put the batteries in with the correct polarity (that is, the + and the - pole correctly oriented) ?

If a smaller disc battery, those sometimes are rechargeable and the laptop has to be powered On from a larger power source (charged main battery, or AC Adapter) for a while, before they will work properly thereafter.

What sign does the laptop give of not recognizing the battery/batteries? and which battery/batteries are they?

Customer: replied 1 year ago.
1.the lion batteries from the six in the pack
2.there are in the right polarity. Measured almost 12v across
3. The laptop''s ***** *****ght is blinking and the power management battery icon is crossed. In my opinion the mbs should be somehow reset. The batteries have the same am per like the original
Expert:  Russell H. replied 1 year ago.

Are you sure that only 2 of those batteries in the pack, were or are defective?

Why did you replace those 2 and none of the others in the pack?

Are you sure that the 2 that you did put into the pack, have a good electrical connection?

Customer: replied 1 year ago.
Well before i replaced them they worked for short periods lets say half an hour when i pprayed open the pack those two were dad. The voltage after replacement was ok too
Expert:  Russell H. replied 1 year ago.

It may be that others were either dead or subject to lesser problems.

It is not usual for power circuitry in a laptop to need a 'reset'. Swapping batteries is usually sufficient.

Where exactly does the battery-with-a-cross/slash icon seen?

Customer: replied 1 year ago.
in the power monitor of the laptop
years ago i replaced batteries in a thinkpad laptop, with the same results, than i replaced all of them
when the battery is reaching the treshold voltage the controler shuts down the circuit and therefore i asked you guys perhaps knows something about reseting the controller inside the battery
Expert:  Russell H. replied 1 year ago.

I admit I do not know about that operation, if it applies to your model of Thinkpad, so it is only fair that I Opt Out, opening the case to other Experts in this category - and I hope that an Expert who has the knowledge you need will take up the case soon.

Expert:  Gary Jensen replied 1 year ago.

Hello there, my name is ***** ***** I will be working with you on this issue. Everything I have read about the T41 with a flashing ***** *****ght indicates a bad battery. Although there may be a voltage across 3 batteries, but that isn't the whole circuit. You indicated that there were 6 batteries. Can you measure the voltage on the output pins of the actual battery housing? It is possible that the protection circuitry in the battery has been blown while opening the battery housing, removing old batteries and reconnecting the circuit when installing the 2 new batteries.

Do you have another battery for this laptop that you can verify will charge in it still? Also, you wouldn't happen to have access to another T41 (or other Lenovo Laptop which uses this battery) in which you could place this battery in and see if the behavior moves with the battery, or stays with the laptop.

If you want to try to reset everything, you could try removing the battery, unplugging the power adapter, then pressing and holding the power button on the Laptop for 30 seconds or so. Then put the battery back in, plug in the power supply and see if the problem goes away.

Another possibility is that the power adapter isn't the correct adapter for this laptop. I have seen cases where, even though the power adapter is the correct voltage and current and the plug fits into the laptop, if it doesn't have the correct chip to identify it to the laptop, the laptop will not charge. It will still run on the power adapter, but it will not allow the battery to charge. Are you using the original OEM power adapter that came with the laptop?



Expert:  Gary Jensen replied 1 year ago.

Here is a link to an article which seems to describe the situation you are in:

Have you checked to make sure that each parallel pair is directly connected to the controller board? Also, can you find the fuse and verify that it hasn't blown?

Regards, Gary

Customer: replied 1 year ago.
i measured the output voltage on the battery contacts (the plug connecting to the laptop) and it was zero. therefore it seems to me that the protection circuit is the culprit. in newer laptops of lenovo like the t400 the battery can be reset through the laptop in case that the battery indicator is faulty.
i have checked every battery in the pack and for sure there are not shorted. the tape coming out from the 6V and going to energize the control circuit works too. there are two possibilities one that the control circuit is damaged and the other that somehow it should be reset. i charged the batteries to full befor soldering them.
Expert:  Gary Jensen replied 1 year ago.

Here is a video which describes your problem, and what they did to try to reset the control circuit. This isn't done via the computer but in the battery and the control circuit. To me this is the "last ditch" thing to try. It seemed to work for him. Note that the battery for the T40 and the T41`are the same so even though the title references the T40 battery. It is the same battery and, therefore, the same procedure should be correct. Here is the link:

Let me know how it goes.


Expert:  Gary Jensen replied 1 year ago.

This is Gary from JustAnswer. Just checking back to see if you were able to get your battery working. Please let me know.



Customer: replied 1 year ago.
well i have tried it too without results. i was thinking if someone have some experience in those battery controllers because it seems to me that because of the low voltage the switching fets? is in cut off state or the memory chip should be reprogrammed for a new battery? i don't know ans kinda was hopping to get some help from you
Expert:  Gary Jensen replied 1 year ago.

Well, this is a bit outside of the scope of typical computer maintenance/repair. Unfortunately, when you break open a sealed battery with a controller board, you risk damaging the components. This can befrom ESD or from shorting accross leads when resoldering or connecting these components. If the procedure above didn't work, I'm afraid that they've circuit board may be damaged. I'm sorry to have to be the bearer of bad news. I am going to recommend buying a new battery.

Good luck!


Expert:  Gary Jensen replied 1 year ago.


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