Hexfet power mosfet help please!!!

[roltex_rohit123]

hi guys i am now building a circuit to desulfate battery at higher frequencies upto 2 MHz using 4046. now the old version using 555 timer used switch irf9z34 which has g-source 20 v max. but 555 operated at 12 volts and 4046 at 5 volts (for me) and its output voltage should not be more than 5 volts. i have a question whether i could use the same irf9z34 for this circuit also? please help this is the only component left now. or what could be the other switch used? the the circuit of desulfator with irf9z34 is given here and my maximum output is 4.8 volts. can i use this irf9z34 or please suggest me some other switch.
Thank you.
Happy New Year to All!!!!

 

[MikeMl]

These "desulphators" are a total waste of time. They do nothing that a good float charger doesn't already do. I have posted several long posts previously about this.

 

[roltex_rohit123]

These "desulphators" are a total waste of time. They do nothing that a good float charger doesn't already do. I have posted several long posts previously about this.

hey mike you feel so? still I wanted to try!! can i expect an answer from you? i gues i would not stop building this circuit and see that its real a waste of time.

 

[mneary]

The poll is dumb.

 

[Vizier87]

The poll is dumb.

I second that man.

 

[MikeMl]

hey mike you feel so? still I wanted to try!! can i expect an answer from you? i gues i would not stop building this circuit and see that its real a waste of time.

The gist of my argument goes like this:

1. There is only ONE way of dissolving the sulphate that forms on lead-acid battery plates; keeping the Specific Gravity of the acid high for a long time, weeks to months for a badly sulphated battery. All the IONic resonance talked about in the pulser literature is mumbo-jumbo, patents notwithstanding!

2. There is only one way to keep the SG high; keep the battery charged between 90% to 100% of its full capacity. It takes a well-regulated CONSTANT-VOLTAGE power supply set to the correct float voltage +-0.1V to do this.

3. The reason that lead-acid batteries sulphate in the first place is that they are allowed to sit around with less than 90% charge while not being used. Batteries self-discharge ~ 2% to 10% per month (depending on ambient temperature) ; an idle battery discharges below 90% of full capacity in a month or two. Continuous float charging prevents self discharge, and simultaneously keeps the SG in the range that dissolves sulphates.

3. That stupid 555 + FET de-sulphator from the internet is nothing but a primitive switch-mode CONSTANT-CURRENT power supply. Constant current charging of lead acid batteries is very bad because over time it leads to severe corrosion of the plate grid. The pulser average output current is low enough that it takes it several weeks to damage the plates. Its only benefit is that while connected, it slowly raises the battery voltage to the fully-charged voltage range and above. It takes days to weeks to do what a 1.5A constant-voltage float charger could do in a few hours... If left connected too long, the pulser will damage the battery.

 

[Sceadwian]

roltex, the circuit you posted still use a 555, you can't come even close to 2mhz with a 555, they have a maximum frequency of only about 100khz.
I'd listen to MikeMI's advice if I were you.

 

[roltex_rohit123]

roltex, the circuit you posted still use a 555, you can't come even close to 2mhz with a 555, they have a maximum frequency of only about 100khz.
I'd listen to MikeMI's advice if I were you.

no dear i am not using a 555 timer. it works like increasing the solubility of a substance in a saturated solution by vigourously stirring it. 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.

 

[MikeMl]

...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...

 

[Sceadwian]

No but it does present one possible solution the poster may not have thought of. Removing the plates from the cell and reconditioning them replacing them with new wet electrolyte, you could probably do that several times before the plates were thinned down to the point where they were no longer of use. All it requires is access to fresh sulfuric acid, some rubber gloves and sand paper =\ scuff the top layer off the plates then rough them up to increase surface area. Quickly placing them back in new electrolyte after a quick cleaning, the plates can't be allowed to dry or they'll oxidize. So it'd require heavy duty PVC gloves and wet sanding with the sulfuric acid.

However a completely electrical solution to the problem will not work in the long term.

 

[roltex_rohit123]

hi guys can you all please guide me the question of irf9z34 in my new circuit? i have constructed something much different and exciting than the schematic. the schematic posted here is just to tell about the irf switch. but in my circuit the situation is as given:
output voltage is 4.8-4.9v; 20uA can i use irf9z34 for it. will it burn my ic? please guys i dont think arguements would help me. i will post my schematics if my experiment is a success. but for now can we get back to work? and do tell me how you celeberated new year!! i will be starting a new, more practical project after this one but first help me completing this one. may be a dumb one, but this is my first project, i dont mind this one failing.i have also bought all the components and fully invested, and if i dont construct this one, then my mate would be furious.To tell something, this not only pulse the battery but there are many advantages over the old one.

 

[roltex_rohit123]

waiting for MikeMI sir's reply...

 

[roltex_rohit123]

Anyone here to help????

 

[desigirl36rocks]

[removed by moderator]

 

[smanches]

So you're calling me an idiot, huh?

That mosfet could work fine, but you'll need to add a driver to it. It turns on at -10V, so your 5V supply is not enough. Plus, 20mA of current is MUCH too small to make it switch quick enough; you'll need something more like 1-2A. Add a high-side mosfet driver using the 12V supply and it should work fine.

Either way, you're going to need some sort of driver due to the 20mA output limit.