Dell Latitude E7440 battery not charging only works on AC Adapter LA-9591P

[Grucha98]

Hi, i have problem with dell E7440, battery is not charging. Idk all story. Original Dell Adapter broken up (its not give 19V) i guess first ac adapter broken up and it broken charging circuit in laptop. Laptop has clone battery (Green Cell)

Laptop works on clone adapter, and its not charging battery. Like on photo. I checked mosfets near battery plug. They are not shorted. But on PQ809 and PQ810 are low on diode mode (both 0.25V) I desoldered them and check on bench and they are good both 0.5V on diode mode. I checked only drain - source way. So its board circuit it should be higher, i guess.

I checked PQ704 pin 2 to pin 5 0,53v in diode mode. PQ706 seems suspicus to me, a little lower on diode mode 0,41v i replaced it with AON6594 it has 5A less (40 vs 35) but i think it doesnt matter in that case.

I dont know how to fix that, i dont have experience with laptops (charging circuit). I repaired a few pc motherbaords and a few GPUs only. I'm gonna be grateful for any advice. I attached schematics and boardview

[mon2]

Laptop works on clone adapter,

This is a DELL so only Dell branded power adapters will work with the logic board. There is a 1-wire communication device embedded inside the power adapter that is powered by the logic board and only if the communication line is working will the specs be extracted out of this 1-wire non-volatile memory device.

What are the details of the power adapter as reported by the BIOS? Do the specs match what is required for this exact laptop? If the power specs are lower (wattage) than expected, then the laptop will be throttled and the battery will not be charged.

[Grucha98]

Thx for fast reply! Maybe should I try repair the ac adapter first 🤔 Second Ac adapter is stronger than previous one

[mon2]

There are articles on the internet that will allow an Atmel (or similar) microcontroller to emulate the 1-wire protocol to spit out any power rating you wish. This can be dangerous if the adapter & emulator device are not matched but it is more of a FYI. Best to source a Dell original adapter.

GitHub - KivApple/dell-charger-emulator: Emulator of original Dell charger using ATTINY85

Hacking the Optiplex AC adapter protocol… I hate Dell. : r/homelab (reddit.com)

I think this is more practical - USB Type C to Dell adapter emulator. The Type C end will negotiate out 20V @ high current (be sure to use a good adapter here) and on the Dell side, will pacify the 1-wire specs. Cool idea.

USB Type C USB-C to 7.4mm x5.0mm Adapter PD Emulator Trigger 90 Degree Angled for DELL Latitude XPS Precision Vostro Adamo Studio Inspiron : Amazon.ca: Electronics

Check Aliexpress for these.

USB 3.1 Type C USB-C to DC 4.5x3.0mm Dell Adapter PD Emulator Trigger 90 Degree Angled - AliExpress
* confirm which power rating the DELL connector will support - this is important to know
* ideally you want 100W on the Type C end and 100W on the Dell side (or at least enough to power & charge(!!) this laptop) - low current / power will throttle the laptop and not charge
* update - see the graphic below that explains it all

[Grucha98]

Thank you very much! I will try repair Ac adapter tomorrow. And I ordered that emulator. Thanks! Maybe laptop's charging circuit is OK 🤔

[mon2]

Continue to update this thread with your progress. Interested to confirm if the linked emulator works for your case.

Sharing more reading material for future reference:

Hacking Dell Laptop Charger Identification | Hackaday

Hacking the Dell laptop power adapter | My Not-So-Boring Life (wordpress.com)

Hacking the Dell laptop power adapter — part II | My Not-So-Boring Life (wordpress.com)

Hacking a Dell power adapter — part III | My Not-So-Boring Life (wordpress.com)

Hacking a Dell power adapter — final (not really) | My Not-So-Boring Life (wordpress.com)

GitHub - HclX/DELL_POWER_SPOOFER: A MSP430 based design spoofing dell power adapter identification

[Grucha98]

So I'm watting for that emulator, but i repaired AC adapter and battery is charging so You're right it was only faulty ac adapter. Thank you!