Notes on the Bible, by Albert Barnes, , at sacred-texts.com
2 Chronicles 18:1
The present chapter runs parallel with Kings, which it closely follows, only adding a few touches.
2 Chronicles 18:2
After certain years - In Jehoshaphat's 17th year Kg1 22:51, not less than 8 years after the marriage (marginal reference note).
2 Chronicles 18:31
And the Lord helped him ... - There is nothing correspondent to this passage in Kings. It is a pious reflection on the part of the author, who traces all deliverance to its real divine source.