Albert Barnes Commentary 1 Kings 15:2

"Three years reigned he in Jerusalem: and his mother`s name was Maacah the daughter of Abishalom." — 1 Kings 15:2 (ASV)

Three years – More precisely, the reign was not much longer than two years (compare 1 Kings 15:1 and 1 Kings 15:9). In Jewish reckoning, however, any part of a year can be counted as a full year.

His mother’s name was Maachah – Or Michaiah, as noted in the marginal reference.

The daughter of Abishalom – Absalom appears to have had only one daughter, Tamar (2 Samuel 14:27), so Maachah must have been his granddaughter, not his daughter. Her father was Uriel of Gibeah (see the margin), whom Tamar married. Maachah was named after her great-grandmother (2 Samuel 3:3).