The Otago Sparks captain struggled with her timing initially, but helped whack 57 off the last five overs to get the home side through to a formidable total of 153 for two.
It was the 34-year-old opener’s third half century in the competition and takes her back to the top of the run-scorers' list.
Auckland lost captain Lauren Down in the opening over of the chase, out for a golden duck, and never threatened the target.
Katie Perkins top-scored with 29, but the Hearts laboured their way to 108 for nine.
It was a pursuit absent of courage, but the Sparks did bowl with excellent discipline.
Strike bowlers Molly Loe and Emma Black took two wickets apiece.
Black had the opportunity to nab a hat trick and rapped Holly Huddleston’s pad. But the ball was nipping down leg and it was an easy not out decision. She had to settle for a double-wicket maiden, which is almost as rare.
Spinner Eden Carson nabbed three wickets in the last over and finished with four for 12.
It was the Sparks' third game in four days and their sixth win in seven. They sit on top of the competition standings with 24 points, but Wellington (20 points) is unbeaten and has two games in hand.
The Sparks actually got off to a sedate start. Huddleston even snuck in a rare maiden to keep them pinned down.
Bates had seen hardly any of the strike, but got her innings going against Molly Penfold.
The Auckland seamer bowled a series of wides and Bates clipped her to the boundary twice. The over went for 17 runs and was a much-needed boost to the run rate.
Polly Inglis (15) had got herself tied down, though. She tried to hit her way out but sliced a delivery from left arm spinner Fran Jonas in the last over of the powerplay.
Bates and Katey Martin warmed to their task, and midway through the innings the Sparks were nicely placed at 62 for one.
Martin was hitting boundaries, but not always finding the gaps, and the dots in between were mounting.
She was dropped on 27 and again on 29. The intention was certainly there, if not the execution.
Bates had a moment as well - and should have been caught out on 45. Huddleston missed a simple chance and, shortly after, Bates brought up her half century.
Auckland must have had half a dozen opportunities to break the partnership, but found a way to muck it up almost every time.
Martin was eventually run out in the penultimate over for 40 while doing her best to get back for a second.
The pair had put on 93 from 76 balls and Bates struck four fours from the over.
The last five overs were extremely productive for the home side. Bates was on the prowl and contributed the lion’s share of the runs the Sparks added.
It made all the difference.
