An accomplice, Luis Osborne, 19, was sentenced to 10 years and four months for willful cruelty to an elder and second-degree robbery.
Natalie "Sandy" Herbst-Vinge, 76, testified that in December 2008, a door-to-door salesman choked her until she was unconscious in her La Mesa home, tied her hands with duct tape and drove away with her in the hatchback of her car.
The woman suffered a minor heart attack during the ordeal.
She was saved, 26 hours later, when an alert sheriff's deputy spotted the vehicle and pulled it over.
In an earlier hearing, Herbst-Vinge testified Nelson sold her a vacuum about a month before the attack and returned to her house, reportedly to make sure it was working properly.