Hi,
I don't want to get too fancy charging other batteries and the like. Your right 120W, what I meant was that the mosfets when passing 5amps would loose 6w in heat....
So what I was thinking was loosing the remainder (eg 114W) through a coil wired in series with the mosfet so that the reactance of the coil would indeed dissipate the power.
Of course, this all depends on how big the coils are going to be.... and in the above scenario, there would be 5 of them.
The benifit of this design would be not as much heat generated as most the power is being lossed as emf in the coils.
Squib