I was doing a research on desulphators and i came across many of the circuits claimed to give the high voltage and high current pulse at the terminals of the battery
i pick a design from the frontiersprings.com, made the circuit and tested it but unfortunately the circuit did not increase the voltage at all.
i have faced the following problems during my experiment.
1. MOSFET gets hot (although the duty cycle from the 555 timer was correct.)
2. There was no change in the voltage or current it is same as 12v as before.
3. i also simulated the circuit on the proteus(simulator) but results are nil...
attached here is the circuit diagram
if anyone can help or guide kindly do??

 

Does it make a low humming noise? If it do it may be working. Also take a look here http://home.comcast.net/~ddenhardt201263/desulfator/lowpower.htm if you have not done it already

 

In the Frontier Springs version, the MOSFET has the drain and source connections reversed. It won't work like that.
C1 and C4 should be rated for 25V or more. 16V is not adequate.

[eta]
C1 should really be 220uF.

I edited a copy of the schematic. See the attached.

 

μ

In the Frontier Springs version, the MOSFET has the drain and source connections reversed. It won't work like that.
C1 and C4 should be rated for 25V or more. 16V is not adequate.

[eta]
C1 should really be 220uF.

I edited a copy of the schematic. See the attached.

Thank you for your prompt reply. I had already corrected the drain and source connections on the MOSFET. my C1 is 47 μF 50 V, C4 is 100 μF 35 V. They do not seem to work .I will replace C1 with 220μF .I hope it works.

 

Does it make a low humming noise? If it do it may be working. Also take a look here http://home.comcast.net/~ddenhardt201263/desulfator/lowpower.htm if you have not done it already

Yeah i have read the article you have refered
and Yes it is making the humming noise but there is no change in the voltage and electrolyte is in its previous state no change.

 

This take about a 4 weeks to complete But it may be that your battery is beyond the point of saving.

 

This take about a 4 weeks to complete But it may be that your battery is beyond the point of saving.

Is there any other indication other than humming noise to check the working of de sulphator???

 

Is there any other indication other than humming noise to check the working of de sulphator???

 

Do you have an oscilloscope aka O-scope? It's kind of difficult to diagnose these things without that kind of equipment, as they put out bursts of voltage at various frequencies.

It's dry weather even in Florida, which is unusual. When humidity is really low, ESD (electrostatic discharge) is a big problem when dealing with FETs. One little "zap" and they are toast.

 

humidity over here is 87% in the evening so its not the problem
but i donot have the oscilloscope

 

First of all I am not expert in this topic The humming sound may tell you if the circuit works. But it will not tell you about how successful the ongoing process is. If the process works you will se see a slowly increase in the battery EMF. This because at least in theory. The battery desulfator process removes the sulfate coating the builds up on the lead plates in lead-acid batteries, and increase the battery internal resistance

 

What did you use for the inductors?

They need to be pretty heavy-duty, capable of at least a couple of Amperes of current.

You may have burned one of them up when the MOSFET was installed backwards. It's body diode would have caused maximum current flow through both of the inductors until the MOSFET diode or one of the coils burned up.

 

I used small inductors one of which burned out in less than a minute.now I l have wound L1 inductor with a 21 guage wire on a iron powder toriod core.L2 has been wound on a ferrite core with 21 guage wire.That would provide enough current rating .

 

Would it be better if we replace 220uf capacitor by 1000uf???

 

220uF should be fine.

However, how are you testing the circuit? Are you connecting it to a battery that is at least 11v?

If your wiring to the circuit is of small diameter, it may be causing much of the pulse to be retained on the board. That could destroy the diode or MOSFET.

Having some pictures of your project would help quite a bit. Can you post some?

Or, at least the board layout that you used?

 

Oh, for those who don't think these things work...

It took a month, but I successfully desulphated a lawnmower battery. Three cells were so heavily sulphated that it wouldn't start the mower, and the electrolyte specific gravity in those cells was nearly 1 (plain water) After a month of treatment, the battery was completely recovered; all cells were back up to 1.255-1.260 in specific gravity.

 

we have connected the circuit to battery which is 12.2v.we measured the output voltage with a voltmeter on the battery terminals,which remains unchanged.

we have not uploaded the pictures because we have assembled it on a bread(testing) board.

you may be right about the light wires. we will replace them with heavy wires. that may solve our problem.

 

220uF should be fine.

However, how are you testing the circuit? Are you connecting it to a battery that is at least 11v?

If your wiring to the circuit is of small diameter, it may be causing much of the pulse to be retained on the board. That could destroy the diode or MOSFET.

Having some pictures of your project would help quite a bit. Can you post some?

Or, at least the board layout that you used?

we have connected the circuit to battery which is 12.2v.we measured the output voltage with a voltmeter on the battery terminals,which remains unchanged.

we have not uploaded the pictures because we have assembled it on a bread(testing) board.

you may be right about the light wires. we will replace them with heavy wires. that may solve our problem.

 

OK, you can't breadboard this circuit, or test it with a typical lab supply.

You'll need to build it on a PCB, or at least perfboard/stripboard, and connect it to a battery using short wires of stranded AWG16 or larger; the larger the better. The power traces on the PCB should be pretty wide.

The longer and smaller gauge the wiring is, the less effective it'll be, as the inductance of the wiring will reduce the peak voltage spikes - which is what you want to deliver to the battery.

 

Thank you very much for the guidence we will implement it on PCB , test it and than get back to you for further guidence.