Solved! ASUS laptop only recognises power cable when battery fully depleted

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samjohnc

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Oct 4, 2016
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I have an unusual issue with my ASUS TP300L laptop (running Windows 10), where it occasionally stops recognising the power cable for a period.

When this happens, I plug the power cable in but the laptop does not seem to notice: it does not register on the taskbar or the charging indicator light, the battery does not charge and the laptop continues to run off the battery. Resetting the laptop does not help.

If I plug the power cable in when the laptop is turned off, the situation is the same: no charging indicator light and the battery does not charge.

This situation can however be fixed: If I wait for the battery to be fully depleted (with the laptop turned off) and then plug the cable in, the cable is recognised: the charging indicator light lights up and the battery charges. If I then turn the laptop on, it operates normally: it registers as being plugged in on the taskbar and the charging indicator light, and the battery continues charging.

I can then use the laptop as normal: I can unplug and re-plug the power cable freely and the laptop recognises it being unplugged and plugged in as normal. At some point however, the laptop will return to its state of not recognising the cable and I need to deplete the power to get it working again. I have not yet noticed anything which triggers this to happen.

I have checked the charging cable voltage, etc., and there appears to be no issue with it. I don't think there are any issues with the battery. I have tried reinstalling the battery drivers and even reinstalling Windows, but this has not helped. I have spent a long time looking for help on forums but have not found anyone else with similar problems.

Happy New Year to all and thanks for any help you can suggest!

(FYI - I posted this question on another thread a few days ago but have had no replies so posting here)
 

samjohnc

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Oct 4, 2016
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Hi all,

I decided to bite the bullet and just buy a new charger as I'd not got any more suggestions on here. It turns out it worked and my laptop is working fine again!

Very odd behaviour and I'm still confused why it charged in some situations and not others, but I'm glad that it's finally solved now at least.
 

Lutfij

Splendid
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MERGED QUESTION
Question from samjohnc : "ASUS laptop only recognises power cable when battery fully depleted"



 

Lutfij

Splendid
Moderator
Can you state what the alphabet after TP300L is? There seems to be a TP300LA and a TP300LD. You will need to narrow down which one you have and make sure you're on the latest BIOS update for your 2 in 1.

If after a BIOS update, you don't make progress, you can then proceed to reinstall your OS after creating your bootable installer using Windows Media Creation Tools.

FYI, please don't create multiple threads on the same topic, it only make a mess when getting answers and co-relating what was suggested.
 

samjohnc

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Oct 4, 2016
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Hi Lutfij,

Thanks for your reply. It's a TP300LA.

I haven't made any updates to the BIOS since I got it so it may well be running an out-of-date version. I will attempt to update the BIOS tonight (I'm at work at the moment) and let you know if it seems to help.

(p.s. thanks for merging the two questions - the previous post was on tomshardware.co.uk and I hadn't realised it was part of the same forum! That's the post I was referring to at the when I mentioned I'd posted the question to another forum)
 

samjohnc

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Oct 4, 2016
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Hi Lutfij,

I've updated the BIOS (I was one version behind) and all seems to be working fine at the moment.

This issue occurs relatively sporadically and so I'm not able to confirm if this has fixed it yet, but I will continue using the laptop and let you know if the issue arises again. If the issue doesn't arise within the next week, I will consider it fixed and respond again to this thread indicating that.

Thanks
 

samjohnc

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Oct 4, 2016
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Hi Lutfij,

The issue occurred again today unfortunately!

I allowed the laptop battery to discharge to around 15% (at which point battery saver mode had kicked in) and then plugged the charger in. The laptop showed itself charging for around 1 second, then flashed that it was not charging for a second and then said charging again. After a short while it indicated it was not charging/plugged in and then has not showed itself charging since, however often I unplug or re-plug the charger.

I had not noticed this 'temperamental' behaviour in the past - it had previously seemed to just stop working instantaneously.

This has made me suspicious that the charger may be the issue. One hypothesis is that:
-The charger works fine when a low current is drawn (e.g. powering the laptop while trickle charging battery or charging battery with laptop turned off)
-This is why it displays the correct voltage when I test it
-At higher currents (e.g. powering laptop and charging a depleted battery) the charger encounters issues which may cause the laptop to disconnect the charging port as a safety precaution
-This means that even when the laptop is then turned off and plugged in (and hence back to lower current draw), the charger is still not recognised; however when the battery loses all power and the system fully turns off, the laptop no longer 'rejects' the charger and the charger is able to charge the battery back up to 100%

Does this sounds plausible, or do you have other suggestions for what might be going on? My assumed next step in diagnosing the issue would be to buy a new charger, but I'd rather avoid the expense if you think there is something else worth trying first! In terms of reinstalling Windows, I tried that before my initial post and it didn't seem to make any difference.

The thing that still confuses me is why, once the laptop stops recognising the charger, it will not recognise it again until the battery is fully depleted, even if the laptop is turned off. That is my reason for suggesting the laptop may have a safety mechanism that 'disconnects' the charging port once it notices an issue with the charger, but in reality I don't know if this safety feature exists or not.

Thanks
 

samjohnc

Commendable
Oct 4, 2016
9
0
1,510
1
Hi all,

I decided to bite the bullet and just buy a new charger as I'd not got any more suggestions on here. It turns out it worked and my laptop is working fine again!

Very odd behaviour and I'm still confused why it charged in some situations and not others, but I'm glad that it's finally solved now at least.
 

ubercake

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Oct 28, 2009
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It's good that you were able to get this worked out. I would have pegged the battery as the problem since it wouldn't consistently charge. Hopefully it stays running as expected.
 
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