how can I keep USB's ports active while in sleep mode?

Thanks so much for this explanation, ShwebM! I was wondering why my devices were not charging unless the display was active. Glad to hear it was something easily fixable and not a hardware issue.

The trick seems to be plugging the USB phone after you've closed the Lord and put the laptop to sleep. The USB remains powered forever. This works with the right hands port on my 2015 MacBook pro w el Capitan.

Just had this problem.

My personal laptop, charged fine if plugging in while laptop was awake. Then can close and will still charge.

On work laptop (same macbook model) it stops charging after maybe 30 seconds.

Seems like the magic setting for me is system preferences -> Energy saver -> Enable powernap.

After turning on, it keeps charging.

Still have to plug in before putting into sleep mode however.