AC adapter not detected, battery does not charge, Elitebook 850 G3

[Qzoomer]

Following up on my posts from June 2022, I am finally getting back to trying to get this computer working.  Symptom is that the battery does not charge when the AC adapter is plugged in.  To date I have done the following:  (1) I have experienced this problem on two consecutive reconditioned computers, the first of which was returned to the vendor.  (2) I have tried several AC adapters, two of which are new.  Problem experienced with all of them.  (3) I have installed a new battery which does not recharge.  (4) I have updated the BIOS to the most current version which did not solve the problem.  (5) I have tested both batteries using HP Support Assistant and both test OK.  (6) When the AC adapter is plugged in, the charge indicator LED on the front of the computer does not illuminate.  It does flash briefly as the computer is powered down using Shutdown in Windows.  The battery icon at the bottom of the screen does not recognize  that the  AC adapter is connected.  When I click on that icon to see the expanded display of battery condition it does not recognize that the  AC adapter is connected.  (7) Leaving the AC adapter plugged in overnight does not increase the charge level of the battery as shown in Windows.  At this point the remaining charge on both batteries is under 30% so my operating time left for further testing  is limited.  Does anyone have any suggestions?  Does anyone know how I might recharge the batteries using a bench power supply so that I might perform further testing?

[erico]

It is not a good idea to open a new thread on a discussion you have already opened. I will move this to merge the two.

I did not realize that a Moderator had archived your post so I moved it back out on its own.

It was likely archived because you did not respond back to another member's reply to you post over a period of months.

You have not let us know if your notebook is still in warranty. Is it?

Your description of the issue leads me to believe that there is component failure on the notebook's system board.

It could be something as simple as the DC power conector on the notebook is damaged or a component of the power/charge subsystem has failed. (Mosfet/Capacitor/resistor}

Power/charge LED lit means that the power adapter and charging subsystem is OK.

A new battery or power adapter will not resolve that.

The notebook needs to be opened up and inspected by someone familiar with the electronic subsystems of the noptebook.

[Qzoomer]

Thanks for your reply.  The computer was purchased refurbished in May with a 30 day warranty which is expired.  SN 5CG7094C2G   I should note that the computer originally received  ( serial number 5CG7084C2Q)  on that purchase exhibited the same problem and was replaced under the warranty with the one I am now testing. The replacement computer  has the same problem, noted upon receipt. Due to other work, I have only recently been able to return to trying to solve this problem.   Because two computers had the same problem right out of the box,  and the probability of that is uncertain, I am hoping that the problem is due to some option setting and not due to (two) a faulty motherboard. In addition to the testing describe in my post above, I performed all of the tests in KB: "Is your notebook plugged in and not charging?" , except that I was not able to perform the power source test as the only diagnostic tests that available to select were hard drive and Memory.  I did not find an option for other hardware tests.

I am a competent technician and have a reasonably complete shop and test equipment.  Is there a schematic available that would allow me to test the charging port input connector and circuits?  The charge LED does not light other than the brief flash on power down.  Otherwise it is dark.

I note that the AC adapter is described as a "smart" adapter and that there is a center third contact.  Does this imply that the AC adapter can be controlled by a signal via the charging port?  Is it possible that the adapter is being shut down when it should not be due to a hardware or software issue?

[erico · Accepted solution]

Hi.

No, that does not sound like a settings issue.

It sounds like component failure on the system board in the charging circuit or on of the voltage rails. It could be a MOSFET, cap, blown fuse(zero ohm resistor).

With both laptops having the same issue out of the box, perhaps the same technician worked on them and missed the very same issue on both.

As far as testing the DC input header, that is simply a test with an ohmmeter.

Schematics for notebooks are, as you already know, difficult to come by if you are not in the PC/notebook repair industry. There are websites where you can purchase them online and enthusiast forums  where is is a possibility to find them simply by asking the members. Unfortunately I cannot direct you to the forums.

If you purchase refurbished notebooks as a matter of course, it may not be a bad ide to stress test them for a few days before sending them on to wherever they are meant to go.

Since laptop #2 had the same issue upon receipt, I do not understand why you did not immediately return it and demand a refund. I am a bit of a hard case when it comes to products with warranty that repeatedly do not meet the advertized expectations. 

[Qzoomer]

Yes, I should have returned it immediately but other aspects of life got in the way and distracted me from this project until the warranty was gone.  The vendor told me to update the BIOS, a procedure also noted in the forum and KB, but the battery ran down before I could do that as the BIOS update wants at least 50% to start without sensing the adapter plugged in.  I am not all that happy with the vendor who should have double checked the replacement unit before shipping it and also should have done the BIOS update to make sure.   At any rate, that's all in the past now.

I will see what I can do to probe the circuit board around the adapter connector for clues.  Hard to circuit trace on multilayer boards which I assume the MB is.  I will also look around for schematics.

For what it's worth, at least this project is a one-off.

Thanks for your help.

[erico]

You're welcome. 

Yes, indeed. Life can get in the way sometimes.

[Qzoomer]

Final follow-up on this problem.  I found a service manual online (no schematics) and disassembled the laptop so that I could check the motherboard.  I found an accumulation of gunk on the MB in the area of the adapter connector that appeared to be the remains of a coffee or soda spill into the computer via the keyboard.  Fortunately it was water soluble so I cleaned it up really well, dried it well, and inspected.  All looked OK visually.  A voltage test on the adapter connector showed that 19.5 v was getting into the computer and the connector appeared good.  Unfortunately, after I reassembled the computer and turned it on, although the computer booted up windows just fine, the adapter was still not detected and the battery did not charge.  Likely due to damage from the liquid spill.  Time to give up on this one and get another.  At least I have a bunch of good spare parts other than the MB.

Thanks for your advice along the way even though we did not save this one..