Battery plugged in but not charging.

I have recently noticed that the battery on my Dell Laptop, which runs on Windows 10. (64 bit) is not charging and displays the note "plugged in but not charging. I have read a number of possible easy solutions, none of which seem to work. The adapter and leads etc seem to be in order as the laptop runs ok plugged in but without the battery installed. Could someone please guide me as to the most likely source of the problem and a possible solution. I should add that when I have previously run diagnostic tests the battery seems to get satisfactory results.

gordon99 said:

I have recently noticed that the battery on my Dell Laptop... is not charging and displays the note "plugged in but not charging...

Is yours a genuine Dell charger? I have had this problem with a second hand Dell that I bought. It came with the wrong charger (an HP instead of a Dell). While it would power the laptop it wouldn't charge it. Fortunately the retailer I bought it from sent me a replacement genuine Dell charger once I contacted them. While I was waiting, I leaned all about Dell adapters.

Dell laptops are particularly fussy about the charger they use. All Dell adapters have a central pin. This is not a power pin, rather it is a serial data line that is interrogated to determine the power supply's specs. If the wire to this pin get's broken or the socket on the PC is damaged then the power supply can no longer identify itself to the laptop. The result is that it may still power the laptop, but will not charge it.

Genuine Dell laptop power supplies use the 1-Wire protocol to send data via the third wire to the laptop (about power, current and voltage ratings). The laptop will then refuse charging if the adapter does not meet requirements.^[4]

1-Wire - Wikipedia

I suspect either your adapter has developed a fault, the wire to the centre pin has broken in the plug (maybe by tripping over the wire and yanking it out of the socket?) or the socket on the PC is damaged. You can confirm that the PC cannot identify the charger by using F2 at start up and going into the bios. The Power/Battery section of the bios should tell you the power output of the adapter if the adapter is being recognised, or show 'unknown adapter' if it is not.

A Dell will only charge its battery when it can identify the power output of the adapter. If it can't (or the adapter is below the power output this PC requires) then it will still power the PC but will not charge the battery. Note that not all universal replacement adapters will have the required 'centre pin' signal.

Thank you for the two very interesting responses to my question. My Dell laptop, model Latitude E5420, is also 2nd hand. I bought it just a few weeks ago when my other laptop, an Acer, had to go back to Acer where they changed the motherboard under warranty. The Dell came with Windows 7 Ultimate (32 Bit) Ultimate and because I get pleasure out of interfering with things I know very little about I spent time and nervous energy doing a free upgrade to Windows 10 Pro. (64 Bit). The Dell seemed to be working fine until a few days ago when I spotted the battery icon not showing a full charge and warning about it being plugged in and not charging.

The adapter is a Dell and the current output puts its capacity at well over 65 watts. The adapter is showing as unknown however at F2. I had not realised that the central pin is a data line and not a power current conductor and I now understand why, if the connection to it is broken, the adapter and power wiring can still be working but not charging the battery. I wonder if there is any way of testing if the wire to the central pin is faulty?
On this point it just appears to me that the power supply, which should be the simplest part of the PC has been over complicated but then, as I indicated earlier, I have no in depth knowledge about the working of PCs.

I have had a go at uninstalling the two drivers under the battery heading in Device Manager but this has not solved the problem and so I will investigate the possibility of installing different drivers to see if that helps.

gordon99 said:

I wonder if there is any way of testing if the wire to the central pin is faulty?

Well, if you can borrow another Dell the easiest test is to plug it into that (or borrow their adapter and plug it into yours). If you can't find another Dell, this may shed some light...

Inside the DELL AC Power Adapter - A mystery revealed | The Laptop Junction

...as will this three (four?) part article starting here:

Hacking the Dell laptop power adapter | My Not-So-Boring Life

Hello Bree & Callender, This morning I fiddled around trying to get the charger to work in the boot process by pressing F2 and the waiting for 10 minutes or so before continuing to log on. The amount of battery charge was still 5% which it was prior to all that. I did this because it was a suggestion from Dell as a possible solution. I then considered updating the BIOS as this is another Dell suggestion to overcome the battery not charging problem.

I then had another look at the adapter to confirm its output which is 130 Watts. Anyway, after an hour or so seemingly getting nowhere I noticed that the battery signal to the left ot the keyboard had lit up. I immediiatly checked the battery icon on the screen and found it was now showing that it was charging and 1 hour 31 minutes to full charge. I decided to leave everything as it was for a couple of hours after which time it was showing 100% charge on the battery.

Later on however I noticed that, although still showing 100% charge, the battery “connected but not charging” message was back. Needless to say I am even more flummoxed. I read all the links you posted Bree and found them very interesting. Nevertheless I am now wondering why the chargeing process had burst into and then died again. Someone, somewhere knows what’s happening I am sure.

gordon99 said:

...after an hour or so seemingly getting nowhere I noticed that the battery signal to the left ot the keyboard had lit up. I immediiatly checked the battery icon on the screen and found it was now showing that it was charging and 1 hour 31 minutes to full charge. I decided to leave everything as it was for a couple of hours after which time it was showing 100% charge on the battery.

Later on however I noticed that, although still showing 100% charge, the battery “connected but not charging” message was back. Needless to say I am even more flummoxed....

All laptops will say connected but not charging when the battery reaches 100%. There is no trickle charge to keep the battery topped up, it would damage a Li-Ion battery to do so.

It is normal behaviour on a Dell for the battery light to go out when the battery is fully charged. Some other brands I own keep the light on at all times a charger is connected, but change the colour to indicate the state of charge. Usually it's amber to indicate charging, changing to green or white when fully charged. The charging light turning off is Dell's way to tell you it's fully charged. Unfortunately this is indistinguishable from the case of no charger being connected, or an unrecognised charger being used.


Interestingly, while I was waiting for the genuine article to be delivered I found that a spare universal charger I had (the sort suppled with a selection of adapter tips for the lead) would sometimes be accepted by the Dell. I'd plug it in a few times until the battery light lit up then leave it to charge normally. I'd see the same effect in the F2 bios screen, about one time in four when plugging it in the bios would show a '90W adapter' instead of 'unrecognised'. So it looks like the center pin may not be the only way a Dell decides if a charger is acceptable. This may explain why your charger sometimes works. My universal charger certainly had no 'third wire' on the lead's own plug. The Dell adapter's third pin had nothing it could be connected to, but still it would charge sometimes.

I still suspect there's a fault or a broken third wire in your Dell charger.

When the battery battery was charging BIOS was showing the Adapter size as the correct figure of 130W. It is now showing as not recognised. There was a period a few days ago when the adapter was showing as 1W, clearly ridiculous.
I will see how things work out before I buy a new charger or whatever. I may be able to get the charger tested on another Dell laptop. Thanks again for your interest and help.

gordon99 said:

I will see how things work out before I buy a new charger or whatever. I may be able to get the charger tested on another Dell laptop. Thanks again for your interest and help.

My interest is personal, having a Dell laptop of my own I want to be prepared should it develops the same problem in the future.

This video covers two common failure modes in detail with good close-ups. Either that the plug/connector needs cleaning/adjusting or that the 3rd wire is broken in the adapter lead's plug (apparently this one is a common fault).


How to repair a Dell Laptop / Battery Charging power problem with an AC/DC adapter. - YouTube

Thought I would give an update on plugged in - not charging problem on my Dell Laptop E5420.
For some days now while using this laptop I have left it plugged into the AC Adapter with the battery showing 100% charge. This morning, on opening up, I noticed the battery was showing 92%. On inspection I found I had disconnected the AC Adapter in error the previous evening, so I reconnected it. Immediately the battery started to charge.
I switched the laptop off and back on pressing key F2 to find that, although charging the battery the AC Adapter was still shown as unknown. I switched the laptop off again and this time I pressed key F12, after switching on, to get into diagnostics. I found that, although the battery was again charging, the 130 watt Adapter power was still shown as 1 watt.
I am mentioning all this just to demonstrate how a Dell Adapter can be working perfectly well even when not recognised by the PC it is powering. I am hoping the plugged in-not charging message is a thing of the past, not to be repeated, but I won't hold my breath.