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My Lenovo Z-series 51-70 laptop doesn't charge the battery all the time (sometimes it does, sometimes it does not). After long periods of leaving it unplugged and turning the laptop completely off, it will charge again, mostly for short periods, and never as long as is needed to fully charge the battery.

It is almost as if something is overheating and needs to cool again. To that end, here are some of the things I have tried to resolve the issue:

  • I've put the laptop in the freezer for 15 mins but no joy there. That was the first thing I tried.

  • I replaced the DC jack (inside) less than two years ago.

  • I replaced the battery but that didn't work. It turns out that the old battery works fine.

  • The AC adaptor is only 18 months old, plus I took the laptop to a store and it showed that the laptop charged using their charger, but alas, it charged with my charger as well. After I got home, the laptop stopped charging.

If my AC adaptor charger is still working, two things need to be shown:

  • #1: When the laptop is in charging mode, both chargers should charge the laptop.

  • #2: When the laptop is in a NON-charging mode, both chargers should not charge the laptop.

I have proven case #1, not case #2.

This brings me to the Peculiarity: If the battery is removed, but it's still hooked up to the AC, the laptop doesn't go on. Unless that's a feature of post 2015 laptops, (that they won't run without a battery), even if they receive power. Before, I was leaning towards the battery being the culprit, but now I'm thinking it's the motherboard.

My questions are as follows:

  • Is the cause of the intermittent charging most likely to be found with a faulty motherboard?
  • Will replacing the motherboard fix the issue?
  • Could it be the BIOS?

Thanks

PS. this is NOT the well known 'plugged in, 'not charging' issue that many talk about.

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3 Answers 3

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It is very unlikely to be a BIOS issue.

It is most likely (after two batteries - neither defective and a change of AC adapter) to be the the charging circuit on the motherboard.

I think I recall on some larger laptops that this circuit can be replaced. But that was a long time ago and I do not believe you can readily change the charging circuit on modern laptops, but I cannot be certain about this.

So the best course of advice at this point is to have the computer serviced to see about the possibility of correcting the charging circuit.

Good luck with this.

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  • Perhaps I should ask this in a separate question, but is it normal these days that laptops completely stop functioninng when the batterry is removed? So, when they're on AC power alone? Because that kinda screwed with my head. I had a laptop with a faulty battery but on AC power it ran fine.
    – GngrWtch
    Commented Dec 10, 2020 at 12:11
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    Is it normal these days that laptops completely stop functioninng when the battery is removed? <-- Some newer laptops do not run on AC alone; some do (usually older laptop). So in this case, (because the issue is intermittent, I still suggest having it serviced.
    – anon
    Commented Dec 10, 2020 at 12:19
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Modern day laptops have charging circuits with smart controllers that communicate with the adapter (how they identify genuine charger).

I'd try and get another adapter in-case it is screwing with the charging circuit causing it to malfunction (did you kink the cable , you know you have signal comms going through that charger cable),i suggest this because if you dont have a multi meter or are not confident in electrical circuits design it may be difficult to isolate the problem.

if you know some electronic knowledge see below.

To isolate the battery vs charging circuit problem you need to check the voltages at the respective points on microchip , this is done by looking up your motherboard schematic or identify chip responsible for charging and seeing if appropriate voltage is present.

.You should check battery signal circuit when adapter is plugged if it enough to trigger the enable pin on the IC for charging and check super io...

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  • Thanks for answering. If it is the charging circuit having trouble with the adaptor, then how do you explain the sometimes hours that it DOES charge and the fact that it worked fine for at least 18 months?
    – GngrWtch
    Commented Dec 10, 2020 at 14:27
  • If you have unstable power it can sometimes glitch the microchip logic .This can be caused by failing caps , bad connections , or even ripple/transients in your mains power.Isolating the problem need to you measure the output of the adapter with an oscilloscope ,Either replace the adapter or remove power to cr2032 and internal battery for 24hrs to reset chip state of superio , in the order that is cost effective :).
    – binaryOps20
    Commented Dec 10, 2020 at 21:48
  • What does cr2032 mean? What do you mean by In the order that's cost effective? Which order? I'm guessing English isn't your native language, so please can you rewrite this? Thanks ;-) <3<3<3
    – GngrWtch
    Commented Dec 11, 2020 at 0:03
  • remove cmos/bios battery & primary battery for 24hrs ,then retest. If symptoms persist try getting a new adapter :) , try those steps in that order, otherwise it has to be super i/o chip/ battery charging circuit on motherboard
    – binaryOps20
    Commented Dec 11, 2020 at 3:18
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I have the same problem with my asus strix gl704, I have found mine was related to the charger adapter, so try that.

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