I have a Lenovo G40-70. Windows 10 Home. I bought it as new in 2017; I keep it running 24-7. The problems started with the battery not charging. I disconnected it for the night, leaving the battery inside. The next day it charged again to 100%. I used the laptop all day long and around 2 AM it refused to charge, the battery depleted and died again. I disconnected it again. Next day, upon plugging in, it charged again to 100%.

Last night it stopped charging again. I disconnected it again, but now the battery does NOT charge to 100%, it just sits at 0%, but as you can see, I can still use it.

After a down time of 15 hours, the battery charges again

Question: So should I replace the battery or the AC cord and AC adapter?


  • Most laptops function without the battery, just as long the AC is plugged in. But here, when all is in a non-charging situation, taking the battery out immediately kills the laptop.
  • The Lenovo Vantage App says the battery is in good condition.

What I tried to fix it:

  • Replaced the AC cable. But charging or not charging, this made no difference either way.
  • Opened up the laptop and checked the Power Jack Dock Connector Flex cable. But it was okay.

Power Jack Dock Connector Flex cable

  • 1
    Get Lenovo Vantage (Microsoft Store) , install it , update it , and run it. Go to the Battery section and check Battery Health. Likely you will find that the battery needs to be replaced.
    – John
    Nov 30, 2020 at 15:36

2 Answers 2


Lenovo has a very decent app called Lenovo Vantage which you can get from the Microsoft Store.

Once you download it, set it up and use (Optionally) the Vantage Toolbar. This shows you the battery percent charge.

Either from the Toolbar or the Vantage App (normally “Start Menu”), look at Battery details to see the state of your battery.

I do agree with the other answer that the battery most likely needs to be replaced.

If it turns out that the Battery is okay (decent given 3 years old), you can set the Battery Threshold setting to Max 80% and min 75 or 70%. Let the battery discharge to 50%, plug in the computer and set the Threshold.

You can check the battery health at regular intervals to see if health is being maintained or deteriorating.

Here is an example from my own Lenovo Laptop.

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  • That's what I thought too, but the Vantage app says the battery is in good condition. I hope you have other ideas?
    – Sara Phina
    Nov 30, 2020 at 16:04
  • You can set the Battery Threshold setting to Max 80% and min 75or 70%. Let the battery discharge to 50%, plug in the computer and set the Threshold. I will add this to my answer for you.
    – John
    Nov 30, 2020 at 16:07
  • @John I think your advice is decent, but in this case I would trust the reality of the battery being intermittent over what a manufacturer diagnostic app states. The reality is it could be the regulator/controller on the battery dying and the random times a connection exists it says, “Hey! I’m fine…” but then the regulator/controller on the battery craps out and that is that. Nov 30, 2020 at 16:14
  • A person can look at Battery Health weekly to probably catch the issue
    – John
    Nov 30, 2020 at 16:17

Replace the battery.

24/7 use for 3+ years will definitely wear a battery down. The battery is most likely dead.

The model of laptop you have is a Lenovo G40-70 which was first released in 2014 and you have owned this one since 2017 and use it effectively all day. That all points to the battery dying. In general the power jack dock connector flex cable would rarely — if ever — be damaged unless something truly serious happened.

Three years of daily use like that will definitely wear out the battery and 3 years is about the right amount of time to have passed for it to finally die. Just get a new battery and your system should be good again.

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