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I would imagine you would use sequential pusing with seperate inductors and then combine through diodes to the battery?

I was not thinking about varying the pulse width for charge control,i was merely thinking of getting a reasonably high voltage sharp waveform in to the battery.

Any sharp rise and fall wave forms will produce plenty of rf,sm psu's are a prime example.

As i have not got in to pic micro controllers i logically thought of using fet driver ic's,the reason being they have a 9amp op driver stage that can cleanly drive large fet gates with ease at 1 mhz!

As you may be aware,generally lower on resistance fets have a higher gate capacitance,also you have a greater "miller effect",this means that some of the drain's voltage gets capacitively coupled to the gate out of phase.
The upshot is the gate may look clean on the scope without the drain connected,but when the drain is switching current,a part of this will show up on the gate.

This is a bigger problem at higher frequencies for a given fet.

This is the major reason for a fets max freq use,for 1kz switching use the big fets should not cause much problem,but for high frequencies pulsing a battery the gate driver current becomes more important for the fet to switch clean.

I suppose a 30v transformer with a limiting resistor in series between the transformer and the rectifier would be a rough and ready method to limit the pulse height,prior to the smoothing caps.
This would reduce the voltage whilst keeping the pulse width constant.
So a sulphated battery would allow say 40+ pulse peak,when the battery starts to conduct,the peak would reduce.

This is only an idea but very dooable.

Also their is no reason why this would not work at 10-50khz frequency.

If only the fast time of the waveform was needed then the width could be used to control the charge current and max average battery voltage(a couple of opamps used for feedback control).

It would be interesting to know if the 3.2+ mhz frequency has any benefit if used properly for desulphation?

Yes i live in the UK.
I am just wondering what the advantage to sequentially firing say 10 fets over using one bigger fet at 10 times the pulse frequency,i thought this would be the same.

Do you still use a very narrow pulse(similar to an inductor),or do you fire the fets at say 1% duty cycle each at 1khz?
Also do you vary the pulse width for battery voltage regulation?