There is no mention of USB-C charging in the manual for this system - coupled with the fact that it ships with a 240W adapter, the overwhelming odds are that it will not charge over USB-C -- certainly not with a 90W adapter. Manual is here.    
Hi, I left my power adapter at home and I'm away on holiday for 10 days. Will a generic USB-C 90W power adapter work?  The AC power adapter it came with was a older style round tip.    
Precision 7760, generic USB-C 90W power adapter?