External monitor connected via usb-c causes mac to not show low battery notification I have a macbook pro 15 inch (2017) that I connect to a 32" external monitor via usb-c. Usb-c is also 'partially' charging the mac but not enough to fully charge battery since voltage from monitor to mac is low. In turn, this causes the battery to discharge while power source is set to power adapter.

Therefore the mac battery is discharging while connected to power. In this case when the battery gets really low no 'low battery' notification is displayed since it is technically 'charging'. Is this an issue apple should fix or do they expect us to check the battery percentage every minute in this kind of scenario.

I was previously very reliant on the low battery notification so now the mac  is powering off just because I am not alerted to connect the proper charger.
Whether or not this is something Apple ought to fix is entirely a matter of opinion. You can report the case to Apple as a bug and hope that they will change the way it currently works.

In the mean time you can install a third party app to monitor your battery that can alert you when the battery charge is low. For example you can install SlimBatteryMonitor, which you can get for free here:

http://www.orange-carb.org/SBM/