Hmmm... I thought I might offer something here just in simple terms.
If you have 2.4amp*hr and 1.5 amp*hr then initially say the first second
there will be 2.4*3600 = 2.4*3600 Coulombs/s and 1.5*3600/s so per s there is more charge flowing through assuming V is constant then P =iV the 2.4A*h...