The Sparks posted a middling total of 118 for nine thanks to a fine innings of 43 from the captain, Katey Martin, and a useful 22 from Victoria Abbott.
The Spirit made light work of the target with opener Hannah Trollip scoring 46 from 35 deliveries, and Anna Peterson struck three boundaries in her undefeated knock of 43.
But it was White Ferns all-rounder Nicola Browne who set up the victory with some outstanding bowling.
She took the key wicket of Suzie Bates and then mopped up the tail, taking four for 17 from her allotment of four overs.
It was a brilliant spell and came the day after she took five for 31 to help the Spirit beat the Sparks by a record margin of 80 runs in a one-day game at the same venue.
Spinner Tanya Morrison was the pick of the Otago bowlers with one for 17, and Bates proved difficult to get away, conceding just 16 runs for her four overs.
The Sparks lost all three games against Northern and have lost their opening nine games (six twenty/20 and three one-day matches) this season.
Experienced pair Sarah Tsukigawa and Clare Taylor retired at the end of last summer and Otago has struggled to rebuild this season.
But despite the some disappointing results, Sparks coach Nathan King was reasonably upbeat about his side's efforts.
"I guess our biggest downfall has been that we have not been able to put all three facets of the game together on any particular day," King said.
"We might bat well one day but bowl or field poorly or vice versa."
There is precious little time to regroup. They play Central Hinds in a twenty/20 games on January 1 and January 3 with a one-day game sandwiched in between.
The Hinds have been struggling this summer as well and the games shape as a battle for the wooden spoon.
