...it works like increasing the solubility of a substance in a saturated solution by vigourously stirring it.
There is nothing about "pulsing" that causes "stirring" of the electrolyte. Stirring acid in a stationary battery is desirable; it happens naturally during charging if the cell voltage is driven to the "gassing" voltage of 2.39V per cell at 25degC. If the cell is gassing, then small bubbles of Hydrogen and Oxygen rise in the solution, and "Stir" the acid. This is why modern three-state chargers drive a 12V battery to about 14.5V during the "charge absorption cycle" of the three-state charge algorithm.
and i stand firmly behind this concept because in our locality there is a power cut upto 12 hours and we have to invest much in replacing the batteries. moreover, the recycling of the batteries is not done the lead is simply thrown in gutter lines. so the only solution is prolonging the life. and i disagree with mike since we cannot stop using inverter or emergency lights as battery discharges below 90% because we cannot afford to buy 2-3 batteries for good conditioning. inverters also dont have a float system since 120-210 ampere battery has to charged in 7-8 hrs. and power cut occurs twice a day for 6hrs. inverters with 4-5 hrs backup at 150 ampere battery are not sufficient. and think what new battery every 2-3 years is impossible to buy. so practically some effort is needed... so i am trying to get something extra than the circuit i've posted. it is not the one i am building. i just wanted to show how irf9z34 works there, and my question is already posted above. thanks.
All of the claims made for the pulsing chargers are for recovery of batteries that have been left sitting unused for months to years, where sulphation is the result of letting the battery sit while discharged.
I have had better luck recovering such batteries by using a fairly aggressive "equalization" charge, where the battery's voltage is driven well into the gassing range by using a ~1-5A constant-current charge for a few hours.
I'm not convinced that the pulser would do anything for a battery that is in daily cycle service. Think of a automotive battery. I routinely get 5 years on batteries in vehicles that are driven at least once per week, no pulsing required. Car batteries are not subject to acid stratification; the acid is stirred by the car's motion, and because the alternator charging system drives the battery voltage to the gassing range while the car is running.
If you have a problem with battery life, it is because you are attempting to use automotive starting batteries for deep-cycle service. The construction of starting batteries makes it such that they have a very short life if discharged to less than 75% of their Amp-hour rating. Deep discharge removes the spongy lead from the plate; when the lead plate reforms during charging, the plated lead is smooth, which has a tiny fraction of the surface area that the spongy lead has, greatly reducing the ability of the battery to deliver its rated current. Pulsing will do nothing for this...