Troubleshoot working laptop HP 840 G1 ?

[AccountSaver]

Laptop turns on ,etc. all working all good ,even upgraded the Keyboard to backlight one.

The problem , is even with Linux,BIOS,Default Win7,Win10 ,swapped 3 batteries from all kind of manufactures which (were good 100%) i even used a HP Original from another laptop that had the same model battery .

But!

It doesn't recognise the battery ,or IF it recognises it and it shows in Windows that exists. It DOESN'T Charge it.

(Yes i have original charger, yes i did even BIOS Updates in case something, yes i have swapped even RAM ,and yes i have only used motherboard connected ONLY with the battery).

Not in a single one, it charges the battery even though it recognises it.

Do you believe it's a chips fault ?

[piernov]

Re: Troubleshoot working laptop HP 840 G1 ?

So you mean it's working from battery only, just not reporting correct percentage and not charging? DC-in jack LED lighting up properly? Does it work from AC adapter only without battery as well?
Paste the result of `cat /sys/class/power_supply/*/uevent` (in the Linux terminal).

[emestee]

Re: Troubleshoot working laptop HP 840 G1 ?

Go to BIOS settings and see if the adapter is identified correctly. On many HP models, if the adapter is not identified correctly, the battery will not charge.

Please read the "charging circuit" tutorial pinned in this forum.

[AccountSaver]

Re: Troubleshoot working laptop HP 840 G1 ?

So you mean it's working from battery only, just not reporting correct percentage and not charging? DC-in jack LED lighting up properly? Does it work from AC adapter only without battery as well?
Paste the result of `cat /sys/class/power_supply/*/uevent` (in the Linux terminal).

To answer them accordingly .
No, it doesn't run in battery AT ALL.
It runs ONLY in Charger mode, and you have to disable or take out the battery, because it "slows" down the computer. But if you leave it on the computer, the battery is "SHOWN" in the Windows, and in the "batteryinfoview" program, but again it DOESN'T charge.
Yes, the charger runs fine (HP original PSU).

Yes,tomorrow will post the result as you request , will try and boot from external USB Linux , disk.

Go to BIOS settings and see if the adapter is identified correctly. On many HP models, if the adapter is not identified correctly, the battery will not charge.

Please read the "charging circuit" tutorial pinned in this forum.

As i have stated, the charger is shown clearly because it is HP Genuine, runs on Elitebook just fine. So the charger IS NOT the problem 100%.

[emestee]

Re: Troubleshoot working laptop HP 840 G1 ?

This has every sympthom of being a charger circuit problem, so the adapter needs to be eliminated from suspect first.

That the adapter works fine does not mean that there isn't a problem with it. The voltage on the central pin of the adapter is set by a resistor to the main rail. The KBC reads off this voltage via an ADC to determine how many watts the adapter is capable of providing. It then commands the charger IC to enable/disable charging and allocates charging current to the battery and throttles down the CPU according to its idea of how much power is available (in point of fact, some HP adapters dont do this with just a resistor, there is an internal adapter circuit that generates this voltage and will drop it for fault or overcurrent). If the resistor is blown, or has changed its nominal resistance, or the main rail is undervoltaged, you will get the exact symptoms you are describing.

While the machine is powered on, confirm the voltage on the main rail, the voltage on the central pin and that the BIOS identification of wattage matches what it says on the adapter sticker, before doing anything else.

[ch3sco]

Re: Troubleshoot working laptop HP 840 G1 ?

This has every sympthom of being a charger circuit problem, so the adapter needs to be eliminated from suspect first.

That the adapter works fine does not mean that there isn't a problem with it. The voltage on the central pin of the adapter is set by a resistor to the main rail. The KBC reads off this voltage via an ADC to determine how many watts the adapter is capable of providing. It then commands the charger IC to enable/disable charging and allocates charging current to the battery and throttles down the CPU according to its idea of how much power is available (in point of fact, some HP adapters dont do this with just a resistor, there is an internal adapter circuit that generates this voltage and will drop it for fault or overcurrent). If the resistor is blown, or has changed its nominal resistance, or the main rail is undervoltaged, you will get the exact symptoms you are describing.

While the machine is powered on, confirm the voltage on the main rail, the voltage on the central pin and that the BIOS identification of wattage matches what it says on the adapter sticker, before doing anything else.

Hi Emestee, do you know what's a proper reading of the voltage on the middle pin?
Do you know if Pin 1 and 3 should be communicated?

thanks,

[emestee]

Re: Troubleshoot working laptop HP 840 G1 ?

I dont know the correct voltage off the top of my head. The schematic for this or similar HP laptop will contain the exact values. You can think of the middle pin as connected to the positive wire with a resistor but in practice this is not the case. As I said, there is a circuit in the charger that can lower this voltage in real time, as a protection method. This also means that if you are powering the machine with a lab PSU, which is a very useful thing to do because it lets you monitor the current draw, you need to lie to the board by feeding it a precise voltage on the adapter detection wire.

[piernov]

Re: Troubleshoot working laptop HP 840 G1 ?

The exact voltage depends on the AC adapter used and the board since part of the voltage divider is inside the AC adapter and the other part on the board, and value of the resistors differ according to AC adapter power rating and from board to board.
Looking at the Inventec Comet Dis schematics, assuming a 90W AC adapter (around 300k resistor) it should measure around 3.25V on the center pin when plugged in (since there is 45.3k+8.66k+8.06k going to ground).

[AccountSaver]

Re: Troubleshoot working laptop HP 840 G1 ?

To answer them accordingly .
No, it doesn't run in battery AT ALL.
It runs ONLY in Charger mode, and you have to disable or take out the battery, because it "slows" down the computer. But if you leave it on the computer, the battery is "SHOWN" in the Windows, and in the "batteryinfoview" program, but again it DOESN'T charge.
Yes, the charger runs fine (HP original PSU).

Yes,tomorrow will post the result as you request , will try and boot from external USB Linux , disk.



As i have stated, the charger is shown clearly because it is HP Genuine, runs on Elitebook just fine. So the charger IS NOT the problem 100%.

This has every sympthom of being a charger circuit problem, so the adapter needs to be eliminated from suspect first.

That the adapter works fine does not mean that there isn't a problem with it. The voltage on the central pin of the adapter is set by a resistor to the main rail. The KBC reads off this voltage via an ADC to determine how many watts the adapter is capable of providing. It then commands the charger IC to enable/disable charging and allocates charging current to the battery and throttles down the CPU according to its idea of how much power is available (in point of fact, some HP adapters dont do this with just a resistor, there is an internal adapter circuit that generates this voltage and will drop it for fault or overcurrent). If the resistor is blown, or has changed its nominal resistance, or the main rail is undervoltaged, you will get the exact symptoms you are describing.

While the machine is powered on, confirm the voltage on the main rail, the voltage on the central pin and that the BIOS identification of wattage matches what it says on the adapter sticker, before doing anything else.

The exact voltage depends on the AC adapter used and the board since part of the voltage divider is inside the AC adapter and the other part on the board, and value of the resistors differ according to AC adapter power rating and from board to board.
Looking at the Inventec Comet Dis schematics, assuming a 90W AC adapter (around 300k resistor) it should measure around 3.25V on the center pin when plugged in (since there is 45.3k+8.66k+8.06k going to ground).

It doesn't even detect it anymore.
Not even in BIOS (3 different Batteries , 3 different brands , even brand new OEM which is used on another Elitebook).
Chargers tried again 3 different ones, because i have in stock many HP genuine ones,and one beast same volt , but 'big' watt 120watt.

But again same behavior.

The linux terminal about the cat sys/class/power_supply/*.uevent gave the result:

POWER_SUPPLY_NAME = AC
POWER_SUPPLY_ONLINE=1

[stingerchamp]

Re: Troubleshoot working laptop HP 840 G1 ?

Only charge plugin , check voltage at battery connector pins, you will find voltage at 3 pins

Measure voltage and write here

[Askic]

Re: Troubleshoot working laptop HP 840 G1 ?

This reminds me of this thread:
https://www.badcaps.net/forum/showthread.php?t=81206

It is most likely a fault on motherboard. There is a Mosfet that protects mobo from disturbance that can come from battery connection port.
Please read this as well: link

[stingerchamp]

Re: Troubleshoot working laptop HP 840 G1 ?

If you really want to open the laptop and check motherboard
Go ahead check voltage at gate of first and second MOSFETs and voltage at all pins of charging ic

[piernov]

Re: Troubleshoot working laptop HP 840 G1 ?

If the battery is not even recognized it's not a power MOSFET issue. The battery won't charge if it's not recognized.
Of course battery is always the first suspect, but it could be an issue on the charging circuit SMBUS.

In general if the battery is good and somewhat charged, even if it's not recognized, the laptop won't turn off right away when unplugging AC adapter. A "new" battery should come charged at around 50% (at worst between 20% and 80%), and so the laptop should at least run for a short while on battery after unplugging AC adapter. Some laptops will turn off after a few minutes if the battery isn't recognized.

[Askic]

Re: Troubleshoot working laptop HP 840 G1 ?

It doesn't even detect it anymore.
Chargers tried again 3 different ones, because i have in stock many HP genuine ones,and one beast same volt , but 'big' watt 120watt.

But again same behavior.

The linux terminal about the cat sys/class/power_supply/*.uevent gave the result:

POWER_SUPPLY_NAME = AC
POWER_SUPPLY_ONLINE=1

Since batteries are not detected anymore, that is why I suspected that charging circuit with protection mosfet on the motherboard is faulty

[stingerchamp]

Re: Troubleshoot working laptop HP 840 G1 ?

Already mentioned if you have inner desire

Check battery junction mosfet and charging ic pin voltage

I wrote all pins as better to check now than afterwards

No one is perfect