# Who has experience with a desulfator for deep discharging lead acid batteries

Discussion in 'OnBoard Electronics & Controls' started by BertKu, Jan 26, 2019.

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### BertKuSenior Member

First at all everybody a successful 2020 and also hopefully a healthy one.
Fallguy, Happy new year in your icy cold condition. (it is here 34 degree Celsius ) Unfortunately I may have to agree with you and also with John Fetter, that it is like a fortune teller, by the time it should happen what the fortuneteller was predicting, that person is no longer to be found. The same with this very lucrative desulfator business, by the time you have discovered that it does not work, either the company is out of business or they tell you a story that it is working for everybody else.

I came to the conclusion that after 1 week intensive charging and desulfating, one should notice some improvement. What do you think about the result. Please note that I had the battery on a trickle charger at the same time because 40 mA x 24 hours x 7 days = 6,7 Amperehour and that would defeat the purpose.
Desulfator2 photo's to Desulfator6.

Battery A : 5th of December 2019 = 11,27 Volt ......... Battery B = 10,18 Volt
( Both for a long time , a couple of weeks) We started with the desulfating on the 24th December
Battery A : 24th of December 2019 at 10h00 = 13,28 Volt .............. Battery B = 13,32 Volt
Batteries disconnected from charger + desulfator for 20 minutes
Battery A : 31st of December 2019 at 09h48 = 12,44 Volt .............. Battery B = 12,32 Volt
Battery A : 31st of December 2019 at 11h45 = 10,85 Volt ...............Battery B = 10,28 Volt
Battery A : 1st of January 2020 at 09h36 = 10,46 Volt .....................Battery B = 10,27 Volt

My conclusion, unless I will be able to find out the energy required for MY MODEL and size and the resonance oscillation frequency and for how long it must resonance at that frequency, + all the same info for any other size and model battery, I have no hope nor have the time to make something what will work.

Please read the manual which I received for those 2 desulfators Photo 3 to 6

Pitty, Fallguy, but I think you will agree with me to stop wasting time and money. they don't work.
Bert

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### fallguySenior Member

The only way I would trust the experimentation is if I could actually see the plates and measure them individually. Of course, this is not so safe either unless you are in a lab setting with proper venting, etc.

My concern is you have a plate that is already beyond repair and that this is the truer problem.

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### BertKuSenior Member

Fully agree, and even then, how do you make the faulty plates oscillating in resonance, an impossible task, for an amateur without equipment and detailed information etc. Have a nice time in Minnesota. Bert

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### BertKuSenior Member

One can only learn from the errors one make. I decided, because the Pulse desulfator was not given my expected result, to open one off my 13 batteries. To my surprise there was not one drop of battery water (de-ionised) in one of the cells. The other cells had very little liquid in them. Although they are claimed as maintenance free sealed lead acid batteries. I have nothing too lose anymore after 8 years of service, thus I filled this one up with de-ionised battery water. It is are now on charge. Let see what the result is going to be. Thanks for your great help Fallguy,

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### BertKuSenior Member

Fallquy, you are totally right. Because the 6 cells are in serial, those desulfators may penetrate the first cell and both plates and do more damage than good. The one battery started to get hot at the one corner WITHOUT any leads. Thus totally damaged. Even the extra de-ionised water did not help.

My conclusion is that the very cheap ones with a 555 Ic is the biggest mass fraud I have ever seen and this is my personal opinion. Millions are being sold. The other ones, the second purchase, have damaged my cells also badly. The batteries are now 5,5 Volt and 6,1 Volt versus 12.3 Volt and 11,4 Volt. I can still use them but in serial for my experimental electronic development work. Maybe, maybe the products works for a single 2,25 Volt cell, but definitely not for a multiple 12 Volt battery with 6 cells. Unless the manufacturer gives sufficient evidence from laboratories or universities that it works, My recommendation is stay away from it. Thanks Fallguy. Bert

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### CraftsmanJunior Member

Hi @BertKu,

While I don't own a boat, I do have some experience with battery desulfation and in particular, the types of devices you have been trying to use and have researched the topic for a number of years as a part-time hobbyist.

A couple of points I would like to make:

1. The 555 based desulfators actually do work. They are based on an article written by Alastair Couper back at the turn of the century for Home Power magazine. Here's a link to the article in question - http://alton-moore.net/graphics/desulfator.pdf. Note that on the first page of the .pdf, it contains an Errata on the original article basically stating that the capacitor used in the 555 timer's circuit was incorrect and the correct value should be used. Unfortunately, in all of the kits sold based on Couper's original design IGNORE the Errata. The change in value changes not only the frequency but the duty cycle of the pulse coming out of the 555. The increase in the duty cycle is the big thing here as it allows the inductor to properly charge up and thereby increasing the output spike of the desulfator. If you replace C2 with a capacitor of the correct value, the circuit's performance will improve.

2. Most kits based on the Couper circuit also have a few poor substitutions that are done to save money on the vendor's side of things:
a. The capacitor C4 is under voltage rated. While yes, the original circuit calls for a 16V one and most kits come with a 50V, people who have built this circuit with the correct C2 value and upgraded inductors (see below) have shown that the circuit can output a spike as high as 60V. Therefore, upgrading that capacitor to 63V or 100V would improve the situation. In addition, the higher voltage rating should also lower the ESR of the capacitor increasing the size of the resultant spike.
b. The capacitor C4 is under capacitance rated. While yes, the original circuit calls for a 100 uF one, people who have built this circuit with the correct C2 value and upgraded inductors (see below) have shown that a much larger capacitor will increase the spike size. In addition, the larger capacitance will also lower the ESR and thereby increase the spike size as well. I've put 400 uF on mine while others have used 800 uF or more. You can also put two or more low ESR capacitors in parallel to reduce the ESR even more.
c. The supplied inductors/coils are just insufficient in the current rating and have a relatively large resistance which will reduce the size of the spike. A good torrid coil should be used as replacements that as spelled out in the article be rated at 6A or more.
d. The connection leads which are supplied by these kits are either too long and/or too narrow. Ideally, these leads should be as short as possible AND be as thick as possible to increase the preserve the spike size when it hits the battery.

3. The Couper circuit is slow especially when used with larger sized batteries - ie a car battery.

4. Since there are so many components that need to be replaced, I would order an unassembled kit from e-Bay and solder in the components myself so that I can replace the ones that need replacing without having to desolder anything.

An alternative design from Barker (http://www.barkeraircraft.com/files/Pulse3_web_layout_.pdf - kit is also available on e-Bay) is also available that uses the power of an AC adapter to trickle charge the battery as the battery is being desulfated. In my experience, this method is faster than the Couper method as it trickle charges the battery as the sulfate is converted. The problem is that you need an AC adapter that can vary in quality and output resulting in the possibility of different results.

What's my 'proof' these things work? I acquired a relatively new (6 months old at the time) car battery which had been abused by the previous owner. According to my battery analyzer, the battery was at approx 50% State of Charge (SOC) when I received it with a CCA measurement of 500 vs the rated 640 CCA on the battery's label. After fully charging the battery and running two reconditioning cycles with my CTECK charger, I was able to get the CCA to 544 of the 640 rated CCA - so a 44 CCA improvement. Next, I used the Barker desulfator design with a 12VAC 1.5 adapter ran through a basic bridge rectifier and capacitor network to produce some lumpy DC power. The desulfator over a period of a week or more slowing increased the voltage measured at the battery's terminal from 15.5V to over 16.43V. My battery analyzer reported that the CCA now measures 705 CCA which is basically a new battery. NOTE> While it took a week or more for the battery's voltage on the Barker Desulfation circuit to measure 16.43V initially, now when I connect the desulfator up to the battery, that reading can be acquired in a relatively short order (ie a few hours if the battery has been recently desulfated).

So, what about the Couper circuit? I don't believe the circuit is powerful enough in the default form to handle car batteries in a relatively quick fashion. I'll bet that the numbers being thrown around are more for smaller SLA batteries even with the improvement noted above. I recently acquired an older but still working UPS with two smallish 9 Ah batteries that are around 3 years old. According to my battery analyzer, both are worn as they have an internal resistance of 40 mOhm and 49 mOhm while the OEM's spec sheet states that they should have about 18 mOhm. I ran both batteries through CTEK's AGM setting twice (not recondition as it might off gas too much since it's an SLA battery) which was a perfect equalizing voltage according to the OEM and the readings were lower - 29 mOhm and 40 mOhm. Now I have them on two separate Couper desulfators - one that is using two larger capacitors and another using 4 smaller ones to see what's the difference. Both of them incorporate the other changes as listed above. I'll post back in a little one once I get more results.

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### BertKuSenior Member

Thank you so much Craftsman for all that information. Although I have 2 batteries which has gone down to 6,7 and 8.66 Volt, I will give it a try again. I will fill the cells up with battery water and experiment with high capacitances. During the Covid19 time, good experience to play around with it, time enough on our hands . Thank you for very interesting articles. Bert

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### CraftsmanJunior Member

Do those two batteries recharge at all - ie their voltages never get to the point where they would be considered 12V batteries (into the 12.5V+ range)? Or do you find that after recharging the batteries fully, the voltage on the battery drops rapidly over a few days down to under 12.5V and keeps going down from there without any load?

If it's the latter, you probably have what I term as a "battery dendrites short" in the battery where sulfate dendrites are forming across the plates in a cell causing the cell to have a high resistance short circuit draining the cell slowly over several days. Battery dendrites shorts frequently happen in older batteries. I had that happen to a car battery of mine where the battery would recharge fully then over the next day, the voltage would read 12.4V and then 12.2V a few days later without any use. Luckily, I might have a solution to battery dendrites shorts... Using the same theory behind equalization charges and desulfation in general, the dendrite that is causing the short in a cell needs to be removed for the cell to return to proper operation. Charging the battery won't solve the problem and neither will standard desulfation or equalization of any sort. What is needed is a violent reaction that will cause the dendrite to crack or break in order to break the short circuit. I've found on the 'net that one person suggested using multiple high current discharges in short order to create a violent reaction in the cell to break these dendrites down. So, I applied that idea to the car battery by doing a few rapid discharges initially by starting the car 4 to 5 times in a rapid series... So what happened? The battery initial measured 12.2V before the starts, then after the starts, the battery's voltage measured 12.5V. After recharging the battery with an external charger, the battery now reads 13.02V the day after the charge was done and holds that reading for a few days.

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### BertKuSenior Member

Hi Craftsman, That is indeed good news. I haven't had the time, but at one stage I was wondering if I would have success by charging my 68.000 uF /63 Volt capacitor with 5 x 12 Volt batteries in serial charged and dump them onto the 12 Volt faulty battery. (Don't worry, I will use gloves dealing with DC voltages higher than 48 Volt) I may even have an 33.000 uF 100 Volt Capacitor. (I am aware that 5 x to 13,3 Volt charged batteries exceeds the 63 Volt, but having sold in my life some millions of capacitors, with 10% higher voltages than allowed, only increases the leakage current, if a capacitor is stored for a long time without being recharged)

Yes, indeed you are right, my 2 batteries are charging to 13 Volt, but basically with very low current. Thus your suggestion will be applicable for those 2 batteries. Over the weekend I will try it out. Thank you to share your experience. Bert

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### CraftsmanJunior Member

Ahhh... someone who knows a lot about capacitors is a wonderful thing for desulfators as much of the thought process for desulfators is basically getting the largest spike possible and much of that comes from choosing the best capacitor for the job!

If you have one of those old carbon pile battery load testers (you know the ones that are basically a heating element connected to a meter and a switch), you can also use that to do a few rapid high current discharges in an effort to blow out the short. Of course, you will have to let the tester sit for several minutes after two or three test cycles in order for it to cool down.

BTW> Here are a couple of links to more information on desulfators:
Lead Acid Battery Desulfation https://www.tapatalk.com/groups/leadacidbatterydesulfation/ -> an old little-used forum but contains a lot of legacy information on desulfation and in-particular using 555s as a base. They also go through selecting and upgrading various components in the Couper circuit.
Lead acid battery desulfator.. https://forum.allaboutcircuits.com/threads/lead-acid-battery-desulfator.36174/ -> Some more talk on desulfation

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### BertKuSenior Member

I have after my disaster with my batteries, read a number of articles, but I trust that your solution maybe the best and has the best chance. Will let you know after the weekend. Bert

Bert

Last edited: Dec 21, 2020
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### BertKuSenior Member

Thank you Craftsman. I did experiment with a 22.000 uF 63 Volt capacitor which I had charged and discharged at 80,5 Volt. 5 x 12 Volt batteries in serial which were all properly charged. Although the capacitor is only a 63 Volt with a surge allowance of 75 Volt. My experience was, that I could take a chance with 80,5 Volt. I did not have time to do it properly and will in the next days experiment longer and more often. The bad 12 Volt battery had naturally an higher self internal resistance, thus dumping high currents was out. But the 80,5 Volt gave me the impression that we maybe are on something good from it. Will come back in a few days time. Bert

P.S. a few hours on. I will have to try a different method. The capacitor discharges itself too slow, due to internal battery resistance. I have to find a way to dump more current during discharging or higher Voltage. Bert

Last edited: Dec 21, 2020
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### CraftsmanJunior Member

You may not have to dump that much current.... I saw an interesting auction on e-Bay today for a BatteryMinder 12041 charger/desulfator. The BatteryMinders are one of the few commercial dischargers that have a ton of positive reviews all over the 'net. The auction was interesting not because I want to buy one BUT what it said on the package...

Notice in the general specifications section where it refers to the "Desulfation Pulse: Up to 4.0A @ 3.26 MHz". To me, they are probably limiting the current spike as the charger can be used connected to car so they probably didn't want to feedback too much current into the car's electrical system. And they are using 3.26 MHz which is right inline with both designs I referred to. According to the reviews I've read for their smaller 1.3A and 1.5A units, it will take about 3 weeks to do it's work which is inline with the Barker design's description. Both the Barker design and the BatteryMinders supply power to the battery as it's been desulfated which might be the key to getting better results over a basic Couper design.

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### BertKuSenior Member

Thank you Craftsman, It looks like I may have to put a charger on the faulty battery with a diode to avoid that the cheap Chinese desulfator will damage the charger. But I have to wait then for a few weeks. In the meantime that was indeed an interesting thread you put on the web. I will certainly experiment with it and see what happens. But maybe I have been to impatient and should give it a better chance with longer period of time. Bert

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### CraftsmanJunior Member

Putting a diode may not be the best idea as it will drop the charging voltage by approx. 0.6V. According to the article by Couper, you can put a couple of ferrite toroid cores between the charger and the battery to prevent the spikes from getting back to the charger. You should be able to easily test that it works with your oscilloscope. Another suggestion that he puts forward is the use of a solar panel instead of a charger.

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