For $29/mo, we provide access to advanced level technicians who will answer your questions on any Macbook board related matter to the best of their knowledge promptly & walk you through how to solve your problem so you can deliver a working board to your customer.
Machine doesn't need a battery to get 20V from charger.
It can works with only 5V from USB port, available from other device (not charger).
SMC must talk with anything connected to USB port to recognize what is.
Looks like charger is not properly recognized in your case; because of charger, SMC, or other internal issue.
Did you try another charger?