T495 3300U refuses to switch over to battery when unplugged

This was a headache since I got the laptop used at a pretty cheap price 2 years ago, I thought, "hey 70 bucks Canadian for a mint T495 with a dead battery? This is a simple fix!"



Anyways when plugged into a good USB c 100W PD charger, I see the laptop actually charges up the battery. Windows 11 shows the battery charging to 100% and the battery health is good.

I can see on my charger that the watts consumed thorough the USB C port goes down once the battery completes charging fully.

BUT when I unplug the laptop from USB C, the laptop shuts down completely. It refuses to use the fully charged battery.


Its not an OS issue as the device will switch off immediately when there is no OS loaded as well.

The lenovo vantage app doesnt help at all, if I remember correctly the system even correctly limits the battery charge to x% when requested in the app, so most of the battery management features still work.

When I first bought the laptop I thought "oh its just a dead battery" I bought a new 3rd party battery from Amazon, replacing the OEM battery, and the device behaves the exact same showing the same symptoms. ⏎

I've disconnected and reconnected the battery connectors, and all other motherboard connectors, cleaned the connectors out with 90% rubbing alcohol, I;ve used the "battery disable for servicing setting" in BIOS, Ive removed the CMOS battery, the main battery and USB C power and left it sitting for a week, and no change. I've reset all BIOS settings, and upgraded the BIOS and downgraded the BIOS, I've pressed that one small SMD button on the motherboard that I thought was some sort of servicing button while the power was on, while it was unplugged, while there was no sources of power connected to the mobo, no change.


I think theres some sort of switching circuitry on the mobo thats defective, besides the refusal to use the fully charged battery, the laptop performs completely fine in every other aspect.

Edit:

Ironic as soon as I posted this, I saw a post on Kijiji for a T14 Gen 1 Motherboard with the Ryzen 4650U CPU and 16gb of ram for 50 bucks, and it was a perfect drop in replacement :)

Had to wait 2 years for it lol

I am going to repurpose the 3300U T495 motherboard as a Desktop mini PC since the battery circuit is flawed