"Ideally, you'd to throw the least amount of pitches as you can," Kelley said. "But on a rehab stint, you want to get your work in."
Kelley, who has been on the disabled list with a strained left calf since April 24, threw 22 pitches in his one inning of work, allowing one walk with two strikeouts.
"It was good. I got to throw all my pitches in different situations," Kelley said.
Kelley will throw again on Monday and Wednesday for Triple-A El Paso on the road in Fresno, manager Bud Black confirmed.
Kelley, who has been free-and-clear of pain in the calf for over a week, was able to institute a few mechanical fixes he and pitching coach Darren Balsley worked on during his outing Friday.
"I kind of throw across my body a little, so if my foot is opening up or my shoulder is, my arm drags," Kelley said. "But my slider was crisp. That's kind of the tell-all. If my slider is good, I'm right. If it's spinning, then it's not right."
Kelley, who has allowed six earned runs over 5 1/3 innings this season, believes that he'll be in a better position to succeed once he's reinstated from the DL.
"I've always been able to turn a negative into a positive," Kelley said of using his time on the disabled list to work on his mechanics.
Corey Brock is a reporter for MLB.com. Keep track of @FollowThePadres on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.