A problem that occurred a few years ago return – my laptop a Lenovo T540p would not charge while it was booted. However shut it down and it charges fine! This problem had just suddenly appeared and was very obviously not a hardware issue. I disabled the power services and remove the battery management entry in Device Manager, powered off fully (shift + shutdown) and the laptop booted back up and recognised the power supply again… of course I’d lost all power management features! Turn the services back on and my laptop immediately stops charging.
Less than impressed, I gave Lenovo a call. Their response was you need to rebuild your machine – it is a software issue and we don’t support that. Rather peeved I persisted with them, and eventually we identified that the issue was simply that I had my laptop in aeroplane mode. Taking it out of aeroplane mode fixed the issue and laptop resumed charging. Further research revealed the following document https://support.lenovo.com/gb/en/documents/ht100574 which explains this occurs with 135watt and high battery packs (which I am using) to protect the seat socket on the plane from being overloaded.
It appears this isn’t a factor of the rating of the power supply, but the rating of the computer. This means just using a 90watt supply will not avoid the issue. I appreciate the reason Lenovo implemented the feature, but at the very least it should pop-up a message that informs you when in aeroplane mode and connected to a power supply the reason why the power supply is disabled. Oh and perhaps train their staff to be aware of the issue?