It was related to Tesla giving away it’s electric motor payments, Elon said he did it to encourage battery sales.

Opening patents could help facilitate the expansion of battery charging infrastructure and ultimately create customers for Tesla’s future battery factories, Kallo said.

Tesla has a goal of producing a mass-market electric car in about three years, and the company hopes a large-scale factory will leverage its projected demand for lithium ion batteries to reduce their cost. https://abcnews.com/Business/elon-musk-gain-giving-teslas-patents/story?id=24111407