Using Magsafe 1 85w 18.5v adapter for MacBook Pro 2015 15'' I want to use a Magsafe 1 85w 18.5v adapter for MacBook Pro 2015 15", which normally requires a Magsafe 2 85w 20v adapter. 

Is the voltage difference is going to be an issue?
Apple says:


  The MagSafe to MagSafe 2 Converter allows you to use the MagSafe connector on your LED Cinema Display, Thunderbolt Display, or MagSafe Power Adapter to charge your MagSafe 2-equipped Mac computer.