#lazyweb i just got a thinkpad T440p and an aftermarket 170W charger, but it won't charge the battery in it. laptop powers on without issues either from battery, or from the charger, but once both are in, it treats it like the charger isn't there. is there a fix?

i've been trying to look all over for this without any success. there's no error messages, no "plugged in but not charging". if i turn the laptop on with only the charger, it shows as plugged in, and then as soon as i slide the battery in, it's no longer plugged in

well this was a productive waste of time: i managed to replace the 2kOhm charger identification resistor in the plug with a 1kOhm one (make it identify as a 135w instead of 170w) because i thought that would help, but it didn't

what i did find out however, is that while this charger happily keeps the laptop on at high performance (discrete GPU on, high brightness.. haven't run loads yet though, if i plug both AC and battery in with the laptop off, the LED in the AC charger starts flashing...

not any logic flashing but a clearly-something-wrong-with-the-power pulsating, but since the brick happily powers the pc alone, i'm betting there's something bad with the battery charging circuitry in the laptop...

i bought a secondhand legitimate 135W lenovo charger and it won't even power the laptop on by itself. the knockoff one, however, does

(neither will charge the battery)