At Tübingen he wrote Das Tagebuch eines neuen Ehemannes. In 1781 he published anonymously the first volume of his Geschichte des protestantischen Lehrbegriffs; the second, also anonymous, appearing in 1783, and it was completed in six volumes in 1800. It was followed by an extensive Geschichte der christlich-kirchlichen Gesellschaftsverfassung in five volumes (1803–1809).
He died in Göttingen on 31 August 1833. His son Heinrich Ludwig Planck (1785–1831), also professor of theology at Göttingen, published Bemerkungen über den ersten Brief an den Timotheus (1808) and Abriss d. philos. Religionslehre (1821).