Me neither, I just bought it and put it across the battery. Here's an example of one like the one I just bought: https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/ulk/itm/281872297166

I can post disassembly pics if necessary, but probably best to see if it works first

Hmmmm, well if its using the battery to power itself, then it is discharging the battery at the same time. That is the reverse of what the ones I am using do, the Dave Barker design is connected in series with a regular trickle charger.
In my Mk11, I eliminated the need for a separate charger by building a simple power supply into it. I deliberately made sure that the output from the internal supply was less than the final battery voltage so that it is only the higher voltage/current pulses that are doing the charging with very little "pass through" from the power supply.
It is the charging by the use of very short high current pulses that seems to be effective,
And I definitely would not connect any charger in parallel with those shown in the advert as they will be sending "something" into the charger that could damage it.

 

My thoughts exactly, my off the shelf desulfators are actually discharging the battery (hence creating more sulfate overall) by running.

That said, there is one hypothesis that what desulfators do is not dissolve sulfate, but break down the layer of passivation between the positive grid and the sponge lead on the positive plates. I've read that the introduction of desulfators in the early 90's happened to coincide with the mass adoption of modern maintenance-free batteries using a lead/calcium alloy in the grid (which are susceptible to corrosion that gradually causes an insulating layer to form between the grid and the lead - which the pulses from the de-sulfator may be breaking down).

Well, whatever the real reason, your results show that they seem to work. I will report back on mine after a couple more days connected.

 

based on my studies regarding desulfators, the one from ebay will be just a placebo or nothing. it makes 2A pulses, so desulfate average battery will take years and most probably it will not help either

 

based on my studies regarding desulfators, the one from ebay will be just a placebo or nothing. it makes 2A pulses, so desulfate average battery will take years and most probably it will not help either

Interesting data. Well, I'm putting my desulfator to the test as we speak. In about 8 hours I will have the discharge data for my 42Ah car battery that I've cycled 5 times and never delivered more than 9Ah before falling to 10.5V. It's been connected to the de-sulfator for a week. Any increase in capacity should be very measurable because the discharge numbers were extremely consistent between cycles. Fingers crossed.

 

From what I can see, the so called "de-suphators" that are powered by the battery itself would have very little or no chance of being effective. As you and I both mentioned, it is more likely that "de-sulphation" is not actually a chemical process that is going on, but breakdown of the passivation layer on the plates.
My own test results seem to show that short, very high current pulses are needed to break this layer down. Constant low current has no effect on it, and constant high current only damages the battery further by overheating and warping the plates which can lead to internal shorts.

 

OK, from a chemical standpoint, the discharge reaction is Pb + PbO2 + 2H2SO4 → 2PbSO4 + 2H2O. So thermodynamically speaking, a desulfator powered by the battery itself will necessarily result in a net increase of lead sulfate within the battery because the energy consumed by the desulfator will have to come from the forward reaction (breakdown of lead and lead dioxide to make lead sulfate) in the absence of an external power supply.

This does not necessarily mean that it won't work - the high voltage may be breaking down the passivation regardless, and the light sulfation produced (because it's effectively discharging the battery) might be easily recovered in subsequent charges. Racmaster's note that it won't work because the pulses are only 2A is assuming that "if some is good, more is better". I don't know yet whether that is true, nor do I know what the threshhold of current is below which the process stops working. We don't even know if it's proportional (i.e. whether a 20A-peak desulfator will restore batteries 10x faster than a 2A-peak one) because we don't know the mechanism of action and what is the limiting factor. For example, it might be a time-based limitation, whereby the passivation layer absorbs only 2A and anything over that is dissipated as heat.

You could perhaps shed some light on this because you have an oscilloscope so you could try testing the recovery at different levels of peak current to see whether it's linear and whether more really is better.

 

Results are in and they are... inconclusive.

Discharge conditions: 1.5A constant current down to 10.5V, then holding at constant voltage (10.5V) until current falls to 0.4A.
Charge conditions: 20A CC stage, 14.82V CV stage, termination when current is <0.4A.
Equipment: Charsoon Antimatter 20A/300W AC hobby charger

Battery: 42Ah car battery installed into a 2012 Ford Fiesta by the factory. Calcium/Calcium maintenance-free construction. The battery failed to start the car on some occasions so it was replaced. I took the caps off, topped up the cells with bottled water (this was a test to see whether distilled was really necessary), and cycled it as shown below:

1. First discharge: 8786mAh
2. After charging normally, second discharge: 7475mAh
3. After 7 days desulfating with a Wizbang Plus desulfator (inductor-based), and charged - Discharge result 7342mAh.
4. After charging for an extended period, waiting for charge current to decay to 0.2A instead of the usual 0.4A - Discharge result 8962mAh.
5. After attempting an equalisation charge (15-16V for two hours at about 0.5A) - discharge result 8295mAh, and a further 1256mAh to take the terminal voltage down to 9V.
6. After storing for a few weeks, then being connected to the eBay capacitor-based desulfator I linked earlier for a week and charging until current was 0.9A; Discharge result 9586mAh.

There you have it, over one week with the desulfator it seems to have gained 1-2Ah, or about 5% capacity. Now I will put the desulfator across the terminals again and put a dumb (magnetic/transformer-based) charger in parallel (protected by diode so the pulses don't go into the charger), charge it for a day, and leave it desulfating for another week or two, then repeat the discharge tests.

 

Those results could just be a slight improvement due to the repeated charge and discharge, or the de-sulphator. As you say "inconclusive"
It took several cycles and 72 hours to see a worthwhile improvement to the 7 Ah gell cell batteries so I would expect a considerable time and many more cycles to achieve the same with a 45 Ah battery. That is of course if it is in a recoverable condition.
Some of the gell cells would not recover, and I could not find a way of determining which would or would not recover other than by trying.
Luckily, we had a large batch to work with, just one would not really have proved much either way.
It will be interesting to see the outcome of your test.

 

hi LMF, thats very nice testing approach, thanx!

in the meantime i studied a very usefull thread of 50 pages regarding desulfators in czech and slovak languages. based on these info and my previous studying, numbers you measured are very correct and they confirm, that the theory -works as designed-.

first you have seen a slow degradation of capacity, then you applied equalizing, which increased the capacity. this is most probably cause by one unbalanced cell(or more). thats the reason, why the capacity afterwards increased. you just pushed up the unbalanced cell with some extra energy (this happened in both steps 4. and 5.) in point 5 you just overcharged cells a little bit, therefore a small decrease, but still increase in comparison with 1.2.3.... old batteries could have problems with eq on 16v...especially if thats not a stronger deep cycle battery construction...

the success with the small desulfator is visible, but took a week for 5%. which isnt far from my exception that average battery about 75ah will take a year or so...

so, conclusion: works as designed.

back to my findings from the other thread. - based on what i found, they consider desulphators as working devices, using it on daily bases without doubt. they also recommend to use it as a prevention on new batteries, not only as a cure on dead battery...

the biggest difference i noticed is a way the use it. they do not use it on discharged battery as recklessrog supposed and it made sense for me too, as you apply the pulses just to the crystals, not the working PB layer...

they use the desulfator on fully charged battery, in fact during floating cycle, which means voltage floating about 13.8v. as soon as voltage falls bellow 13,00V or so, it automaticly disconnects. so the most of the time it is connected on battery under charging, even if only floating state... this prevents discharging the battery and create another sulfation with desulfator.

what i think about is an internal resistance of the battery. as charged, pulses will not miss the crystals, as there may be smaller chance to dissipate the pulse energy into electrolit. hard to say for me.

anyway, what i missed on the forum was scientifical approach as you did with your measurement, LMF...

just to mention, all their desulphators are about 30A pulses or more, also as fast as possible pulses.

 

Re recklessrog - I think we can discount cycling as being the cause of the improvement - as you can see from points 1 and 2 just cycling the battery gave worse capacity, not better. Certainly for the pasted-sponge-lead construction of car batteries it is well known that cycling harmes them because it causes shedding of active material off the plates. In fact a car battery isn't really expected to last for more than 2-3 deep cycles. I think I've gotten away with 6-7 of them so far because my battery has some other problem (probably a weak cell) that is preventing me from discharging the full capacity so far. Your UPS batteries with solid lead plates will be more robust in terms of deep cycling.

Re racmaster - thanks, I'm a mechanical engineer so I tend to use the scientific method for everything . My wizbang plus has no low voltage cutoff, in fact it damaged one of my old car batteries - I left it plugged in and abandoned the battery for 6 months, terminal voltage reached 7V by then and my hamfisted attempts to recover it before I learnt the proper approach left it completely dead. My capacitive desulfator from eBay has a settable lower cutoff (based on whether it's a 12V, 36V or 48V battery). For a 12V battery the low voltage cutoff is 10.5V.

In 1-2 weeks I will repeat the discharge test and see whether I get 9-10Ah out of it (a further 5% improvement). That would mean a recovery rate of about 5% per week. That would take 20 weeks (about 6 months) for full recovery. It's not bad for a 5-year old car battery.

Pessimistically, I'd wager it would reach "full recovery" sooner considering that there's surely some permanent capacity loss that the desulfator isn't going to bring back, so perhaps at best the fully recovered battery will have 20-30Ah instead of the rated 42.

As for internal resistance - it's surprisingly low for car batteries, and indeed lead-acid batteries in general. Even damaged ones with low capacity. This one registers 40 milliohms with a good quality one-piece cable from the charger's banana plugs to the battery's crocodile clips... and around 60 milliohms if I use a different, cheap cable with a Deans connector in the middle. Fully discharged IR is around 130 mO but quickly recovers, even before charging. Probably because the acid has time to diffuse around the plates a bit. Lead-acid is well known for being a sluggish chemistry.

 

I wonder how well so called leisure deep cycle batteries that are designed for caravans and the like would recover if sulphated. Car batteries are only supposed to supply high current for short periods and not be deep cycled.
The gell cell batteries I have are ok for deep cycling and I did make some detailed studies of the charge/discharges, (see my post 41 as to how this was done) but they are dozens of pages long and would bore the pants off most of the readers on here so I preferred to keep it short and to the point.
Hi Racmaster, I think you misunderstood me, I said that the other de-sulphators were discharging the batteries in use, not that they should be connected to an already discharged battery.
This week we may be getting another load in from the alarm company, these will all be from a school refurbishment and are 4 years old, all fitted at the same time. Once I get round to testing them, I will select one best one, and one worst one and carry out identical tests on each. that should give a clear view of how well each responds. I have made three identical de-sulphators with closely matched components and output. This should reduce any variables due to charging differences.

 

would be interesting reading, cant wait for it

 

So, new results are in.

Recall from my earlier post the last discharge test result was:

• After storing for a few weeks, then being connected to the eBay capacitor-based desulfator I linked earlier for a week and charging until current was 0.9A; Discharge result 9586mAh.

I've left it connected to the desulfator for another week. During this week I charged it with a normal (transformer-based) charger while desulfating. I protected the charger by a diode in series, wired to prevent flow of current into the charger. This morning I charged it with my Charsoon Antimatter - 2.47V/cell (14.82V total) until the current decayed to 0.5A.

Discharge result (1.5A to 10.5V and hold until current decays to 25% of initial value): 11321 mAh

That's a gain of 18% over last week's result. How much is due to the desulfator and how much is due to leaving it on the charger longer (recall I stopped charging at 0.5A this time but 0.9A last time) I can't say. The transformer-based charger may have had something to do with it too because after several hours connected to it I measured a terminal voltage of 15.1V so it's charging it harder than my Charsoon charger does at 14.8V. The battery is charging now. I will connect the desulfator and re-test next week to see if it makes more progress after another 7 days of desulfation.

 

To try and remove the effects of variables due to different chargers, De-sulphators, and charge/discharge levels, I now have made 3 identical mk11 de-sulphators and have made a simple but accurate comparator circuit that limits the final charge and cut-off voltage during the cycling of the batteries. The final charge voltage is 14.4 Volts, and cuts of when discharged to 10.8 Volts
I am building three of them and will make an analogue power supply with 3 independent adjustable current limited 16 volt outputs. ( the comparators will limit the final voltage to the batteries)
I will use the digital mode of an oscilloscope as a data logger and also the method I previously used with the Tenma meter and P.C once I've made a sequential input switch for it.
The first Hi/Lo switch I designed used power Mosfet's instead of relays, but when the charge current reduced to a low level, the effects of RD on became a problem so I resorted to good old relays and another variable was eliminated.
We now have 20 of the same gell cell batteries to run through the tests, Half of which will be with topping up the electrolyte, the other half without.
All will be charge/discharged normally two or 3 times before using the de-sulphators.
All this is going to take some time, but to get really definitive results, it will be worth the effort if only to satisfy my own curiosity and also give some of the members of my club something different to do.
Below is a picture of the Hi/lo switch. and the way I was doing it with the Tenma meter and P.C.

 

thing is coming serious go on!

 

in the meantime...
recklessrog, i noticed your circuit is built on arduino style, which means no soldering, just a breadboard and parts inserted into... im new in this. would like to try and build something, but does it make sense in this scenario? i mean is it good idea to build some desulfator on arduino? does it work in the long term purposes or its just for few minutes of testing?

 

in the meantime...
recklessrog, i noticed your circuit is built on arduino style, which means no soldering, just a breadboard and parts inserted into... im new in this. would like to try and build something, but does it make sense in this scenario? i mean is it good idea to build some desulfator on arduino? does it work in the long term purposes or its just for few minutes of testing?

Hi, no arduino in my circuit, I design then build a prototype on a plugin bread board, and because I am not building many, I use veroboard (stripboard) for the final design. I could make a pcb, but it's time consuming, messy, and unnecessary for these applications.
I've used it for years for many one off or very low volume projects where component layout is not critical, but not so useful at high frequencies due to the adjacent track capacitive and inductive coupling.
You could probably program an arduino to provide the drive for a de-sulphator, but would be a waste of the arduino when only a very simple circuit using a 555 and a few parts provide the drive to the power Mosfet and inductor which you would still need with all the complication of programming and setting up if you went down the arduino route. K.I.S.S definitely applies here.
There seems to be an obsession with trying to make everything code controlled, using micro processors, and tons of code that seems to take forever to de-bug (just take a look at the Arduino forum) when often there is a well proven, reliable, and easy to make analog circuit that will perform the same task.
It reminds me of NASA wanted a pen that would work in space. A million or two dollars and a couple of years later, they had one that worked. the irony is that the Russians used pencils!!!

 

im not hanged on the programming and digital design. you are completly right about the analog way. result is important and if i can reach it easier, its definitly my way... especialy in such a one-purpose project.

as im completly new in this, could you reccomend me something to start with? you know, it doesnt make sense for me to study complete circuit building problematics just to build one copy of desulfator on proven design...

 

im not hanged on the programming and digital design. you are completly right about the analog way. result is important and if i can reach it easier, its definitly my way... especialy in such a one-purpose project.

as im completly new in this, could you reccomend me something to start with? you know, it doesnt make sense for me to study complete circuit building problematics just to build one copy of desulfator on proven design...

This is the first design by Dave Barker that I tried. You could start with that one.

http://www.barkeraircraft.com/files/Pulse3_web_layout_.pdf

 

yes, nice. can i build it on standard breadboard?