We obtain a criterion for determining the stability of singular limit cycles of Abel equations x = A(t)x 3 + B(t)x 2 . This stability controls the possible saddle-node bifurcations of limit cycles. Therefore, studying the Hopflike bifurcations at x = 0, together with the bifurcations at infinity of a suitable compactification of the equations, we obtain upper bounds of their number of limit cycles. As an illustration of this approach, we prove that the familyx 2 , with a, b > 0, has at most two positive limit cycles for any t B , t A .