Desulphation of lead acid batteries is a bit more complicated than just passing current pulses to break up the sulphate crystals. First the battery needs to be emptied and washed to remove any sediment. Next the acid is replaced with new solution mixed to the correct specific gravity. The desulphation charge and pulse cycle is run through a couple of times until the two sets of plates are visibly different in colour when charged. The battery is then drained and cleaned once more before being filled with new acid. The capacity will never be as good as the original specifications but it can be used in an emergency situation to get out trouble if there is no alternative. The rejuvenated batteries will last for perhaps a year before replacement is absolutely necessary. This procedure was used for the emergency battery systems on merchant navy ships where the ships might be away in remote areas of the world for a couple of years before returning to civilisation where new batteries could be obtained. Not a trivial process and very time consuming and labour intensive to carry out properly. The other disadvantage is that any clothes worn when carrying out such battery maintenance dissolves into a mass of holes due to the effects of acid and the acidic vapour.

Scott wasted 30 dayz and made this single compressed video of 11min 🥺 Thanks Scott! ✨

And you turned it into 11 minutes for us, thank you!! Time saved for humanity. I appreciate this so much =)

The circuit I built is very similar to this. I've tried many different combinations of pulse width, frequency, voltage, and current over the last 10+ years. It has never once revived a battery in any way. It might work for some edge cases but a well cared for battery almost always fails with a dead cell like the first battery shown here (either shorted out or falls apart) and this can not be fixed without rebuilding the whole battery.

The electrochemistry of a desulfator is solid, but often the reason capacities drop in lead acid batteries is more from "shedding": lead sulfate is less dense than lead metal, and like ice forcing against the walls of water bottle in the freezer, it can force the lead metal apart from the plate (or force itself off of the plate). This is very common in high current ignition batteries, which use a lead sponge matrix instead of a plate. Desulfators work for a very specific failure mode, but way more often the battery is simply permanently damaged by the formation of large sulfate crystals that either fall off the plate or force the plate apart. In these cases, the desulfator will do nothing more than cause a bit of hydrolysis in the electrolyte with each pulse. Obligatory "desulfation works only at full charge" because otherwise the electrons you're pushing into the cell will only be used for the usual lead-acid electrochemistry long before any desulfation occurs (the E0 values for converting sulfate to acid are just a tick higher than those needed to convert lead ions to lead metal). If a desulfator is going to work, it will need to be used with a float charge that's enough to keep the battery charged between pulses. It need not be more than what's needed to counter self-discharge, and that's going to vary a lot from battery to battery. And then there's the whole issue of lead oxide generation over the battery's lifetime, which also represents a permanent chemical loss of capacity. Long story short, for 99/100 batteries, recycling and chemical processing are the only ways you can really revive them. For that one out of the bunch that's just not been used in a while, a desulfator could work but needs tuning, special conditions, and constant monitoring to make sure that there's no hydrolysis side reactions.

I've always found battery 'rejuvenation' to be no more than folly. If I have a battery that is not doing the job I need it to do, I recycle and replace. Nothing promotes peace-of-mind like a brand new battery. Thanks for the video!

There is a KNOWN good way to desulfate batteries. Take them to a recycling point, where they will be melted down and processed into new batteries. Jokes aside, I have had limited success with this. It seems that it is very battery dependent. I've saved only a handful with a consumer unit but most go to the "core charge" pile.

Mostly unrelated to the video content, but I noticed when you were showing shots of the PCB layout in Altium that your polygons are overflowing the PCB edge. I was having the same issue and I recently figured out how to fix it. If you duplicate your board outline to the Keep-Out layer, you can assign a rule to have your polygons maintain a specified distance from any Keep-Out layer object, and effectively follow the contour of the Outline. Keep up the great work!

I would like to see one video where somebody makes a lead acid cell in a glass jar, sulfates it.... And then does various de-sulfurizing circuits with a time lapse camera.

Lead acid batteries are a bit tricky with their capacites, the 44Ah are messured with a C20 (2.2A) discharge over 20h, if you use a higher Discharge the Capacity is much much lower.

Use a DC welder set to 100-125A for most car batteries. The first battery you had would have been recoverable. Don some gloves and safety glasses. Take a dead battery outside and pop the cell/valve caps off. Fill cells with distilled water to just under the cell opening. You cannot recover dry batteries. Only water, never acid is to be added. Now with the battery outside, connect the welder leads to the battery terminals. Set welder to 0 and power on. Turn power up to about 100A. Using a small mirror, look into the cells and watch for bubbles. If no or low amount of bubbles, slowly increase welder until 125A. Once you see steady bubbling, set a 30 minute timer. At 30 minutes cut power and let battery cool to under 80F case temp measured with a temperature gun. Once cool repeat the 30 minute process. Just leave welder at whatever setting you’ve determined and just flick it back on. Let cool, then hit it a third time. After 3 cycles like that connect to a normal 12v charger (smart charger makes this easier as it cuts off automatically) and just leave it until done. The battery will now operate as almost new. I have 3 750CCA batteries here that are over 10 years old and they start my vehicles in 0F weather, no issue.

I read some on this topic a while ago, and if I remember correctly, the sulfate that is created during normal use is thin, spongy and easily converts back into the electrolyte when charging. Left for too long however, the suflate hardens and does not covert back. The desulfators can in the best case crack this hard layer. This would verify other comments about the process not increasing the capacity (the electrolyte remains weak) but potentially getting an improved current flow (less plate resistance). The pieces nocked off by the process fall to the bottom of the battery where there is a collection chamber. When this fills up and touches the bottom of the plates, the battery is completely toast.

30 days of strategic planning and implementation in 11 minutes video. As a fellow electronics video creator, i can really appreciate your efforts. Thanks for this lesson Mr. Scott

Be aware that lead acid batteries specifically has their nominal capacity of say 50 Ah rating under the implied C20 standard; its the capacity if run from full to flat in a duration of 20 hours, so here at 2.5A nominal.

I love this straightforward demonstration of how the circuit does what it claims to in terms of function but does not give the claimed result. Particularly the fact that you highlighted the importance of actually testing the thing that is supposed to be improved (capacity). At the risk of waaay oversimplifying things, rechargeable batteries are going through the equivalent of rusting and then de-rusting. As another commenter pointed out, the starting and ending materials going from charged to discharged and vice versa have different properties, including how much volume they take up. This repetitive process of changing volume leads to mechanical degradation which cannot be reversed with a circuit.

Thanks for throwing in the issues and fix for the PCB design. I think a lot of people are put off by worrying their boards will not work as intended when they arrive, and as many people have budgetary constraints, find this a show stopper. Being able to diagnose and then repair the design with a workaround means a non-critical design failure is manageable, and you'll learn something along the way too. Dealing with faults and faulty designs is really valuable as a hobbiest, and also if you want to get into component level repair and hacking.

Desulfators do work. I have one and have successfully revived a couple batteries. But it only works if you also add a charger.... In other words u have to charge the battery at the same time you desulfate it. But that was 2 out of 100+ batteries

While travelling a lot for work last year, I had to put the batteries of both of my cars on my big battery charger (the kind with wheels) which went into desulfation mode. I thought it did a surprisingly good job and I'm still using the batteries, but I can't say for sure what a charger without a desulfation mode could've done. Now I want to try to get a couple of batteries and experiment with them.

Dude i have been following you since the olden days of instructables and i gotta say you have always found a way to make projects so interesting even if they were a gimmic or trivial!

I'm glad someone finally tackled this I've been sick of the fake videos for years... An old battery is worn out it's not coming back

Thanks for debunking this finally, I was wondering if there was a way to possibly revive my 102Ah deep cycle battery. We here in South Africa experience daily power cuts 2 hours, 3x per day (referred to as loadshedding by our power utility that currently can't provide our country with enough electricity). I recently lost a deep cycle 102Ah battery due to this constant charging, discharging cycles in my inverter. The battery is just past one year old. Lithium is better, but unfortunately outside my price range for now. Keep up the good work.

It would be worth checking the composition of the electrolyte in the big battery. Often times the batteries dry out from overcharging and need water added over time.

Priceless! This is the content type we need to learn and go forward in knowledge.

Sharing the failures is also part of what a scientist does. Thanks for sharing!!

I use JLC myself whenever I want a nice board. They do a great job. But the price is never just $2. It could cost just $2 or $4 for the board itself (I think the most I paid was $5), but the shipping can be as much as $15-$20, and I have never received it in a week.

3:14 what you might be experiencing here is actually an internally shorted cell or a cell that's been reverse charged. This can be fixed you'd need to charge it with very high current and pulsing it, essentially kinda damaging it in the process a little. Not the best solution but it does work. Now as for desulfation, I have bought myself a battery desulfator, one of the cheaper kinds. It hasn't actually desulfated anything for me but I noticed it did solve some other problems that those batteries had. Self drainage was gone. on 1 battery the voltage would drop down to 12.5v overtime after fully charging it. Now it stays at 13.2v which is a significant improvement so it isn't entirely useless. What I've found that actually desulfates the battery is by just cycling it with high current. I've even gotten lead acid batteries that were at 0V back to 13.1V with this method and it works really well. You just have to stop discharging the battery at 10.5v to avoid reversing the cells. What you should notice is that the capacity increases with each cycle. It might take time till it starts increasing but you will notice it. From my testing it usually takes around 20 cycles to get it back to a good condition

Oh man… I was so happy to see this video and give up to build my “discharger” which was in my mind to “reset” the Pb battery from my alarm system. Now just ordered a new one, thanks you no need to waste more time and energy. Please more Busted videos!

Thank you for leaving in, explaining and fixing the mistake. It greatly helps to deal with the imposter syndrome in me (and I presume the same applies to many other people). Anyone can make any mistake. The question is, what you do to avoid it the next time and what safeguards you build into your habits in general, based on such experiences. In short: how you learn from it. I _love_ this approach, thank you again.

Hi. Good try. But you need to ad distilled water or (more better) mixture of water and electrolytes (1 to 8 mix). Because your separator inside the battery looks like to "dry" and sulfate crystals won't dissolve.

You will never fail to amaze me with your boardless soldering skills. Somehow you make a jumbled mess of leads more functional than anything I build on a breadboard.

It's great that videos like this one are put up. Too many times someone will put up a video making promises and they turn out to be little more than nonsense and in some cases, a lot of these hacks can be quite dangerous. As a technician, one of my tasks is to physically check the batteries and determine their age. For fire alarm systems and most emergency lighting packs, we recommend strongly that the batteries are to be replaced every six years even if they pass the load test. While they may be recharged to full voltage, they would discharge too rapidly to be of use in an emergency situation and can actually create a hazard. An example of that would be a stairwell that is pitch black due to no lighting when the main power fails and the emergency lighting also fails because the battery is too old.

In my experience these things do not increase the capacity but it will increase the current the battery can put out

I have an video idea for you. Convert a lead acid UPC (uninterruptable power supply) to one that uses 18650 Li batteries. Will there be a cost savings? What are the advantages/dis-advantages?

thanks for this enlightening video. now the discussion with my colleagues is over after years. always make sure your battery is in good condition.

you're a genius and you explain things perfect, but the main reason I subscribe to your channel is I'm addicted to the way you say "scooter"

The problem is not that lead batteries only sulphate, they can have lots of other faults, such as internal short circuits, interruptions or most commonly one plate simply stops working. If you've seen YT videos where people in more southern countries repair batteries on the street, note that even these skilled craftsmen MUST buy one plate new, I can't remember which one, it CANNOT be recreated in the kitchen/on the street!

Thsnk you for your video i have been telling people for a long time that there is no simple solution to battery sulphation and that it is not practical for the average person. As usual top notch video from you as always!

just another Great video form GreatScott ! Thanks for this lesson

Very few times I got to make Lead-Acid batteries, that have been through a deep cycle, ever work again. Your results do not surprise me in all honestly. Has anybody though tried to mechanically breakup the crystals? Like with an ultrasonic transducer? I have absolutely no idea if it would work but wouldn´t mind seeing a video on it! :-)

I believe your results. Not sure what's going on with them, either... I can't make sense of why it would drop like that. Hmm... Pretty complicated thing to put together and test for the same amount of time, though.

Your analysis is super bro 👍 As always I learned from your video thanks 🙏

I love your videos

It would be good to see a forklift mechanic's opinion. My old pop used to disulfate and get some good results. Or see what happens if you ran these on the dead battery.

Great video from Great Scott - thank you! 👍😀

Amazing video Scott. Thanks for that

I love magic batteries

The problem is the pulses. They have too short a duration imo and cannot wait sufficiently to break down the sulphate crystals any better. Please note that Maintenance free lead acid battery is not compatible with this technique. Please make a battery protection circuit for a lead acid battery. Would be interesting.

Thank you for your technical integrity. So much false information and fake products across the internet. But, it was also the case when all we had was TV, including now. Beware the pharmaceutical industry.

That's the reason why I love following you Sir. Thank u

Its along the same thing as "free" power. very interesting video 2x 👍

From what I've had heared - reverse charging is one of the ways to restore battery: First You should discharge the battery to 0, by adding a bulb for a day or so Then you connect charger backwards - positive wire to "-" terminal and the positive one - to "+" terminal, charge up, than again discharge to 0 with a bulb and charge this time correctly. The idea behind this is that sulphotation occurs, I believe, only on anods. By charging the battery backwards - anod and cathod are changing places, so sulphates from anod should dissolve.

Very good explanation about bateries cycle life. I have expend a lot money in motorcycle bateries and now I can understand better why by less than a year they failed to me... Thank you for your efford and your time to share all this information to us!! Keep creatived as today!! Regards from mx

It's quite fascinating to watch you build little circuits. Sadly I have no idea what you are soldering together, the only circuit I understand is the one of an ECG. But I enjoy your videos - keep going.

This is what I like about this channel that he will make his own improved version

Awesome as always. Great explanation. Great science. Very clear and concise. Also love your handwriting/drawing :)

I have seen these little circuits for sale for years, sometimes at high prices. I was always skeptical, but didn't have the time or money to pursue it. THANK YOU, Scott, for debunking this for us, appreciate it very much.

I always enjoy your videos. Thanks a lot.

Great Video! Always wondered about this principle. It never convinced me...

Your videos are always interesting and informative.

Very informative video. It would be nice to understand what is happening to the battery capacity. Great content though. You are an inspiration to us that have a passion for creating electronic projects.

It's amazing how whenever I start looking up something on UKposts within a week or so you're making a video about the same thing.

another very useful video, thank you Great Scott

Great! I had one of these circuits on my 'todo list', to recover a few of my dead batteries. It's a bit disappointing to see such dubious results, but at least you just saved me 30 days of dicking around with magic pixie circuits. Thank you, much appreciated! So, perhaps now I'll move to plan 'B' and melt down some of my dead batteries, to harvest the lead.

Awesome video great scott, and great research on the subject of cleaning batteries. I had done similar experiments and can also conclude that it is very hard, or almost impossible to recondition the batteries, specially newer lead acid batteries. New lead acid batteries use powdered lead to increase current but this results in unrepairable plates. Wanted to try one day to create ultra thin lead plates and create own batteries. Best way to revive is not through electricity but reconditioning the acid and plates by hand

I was told many years ago that it was best to use these while the battery was charging not that I've had need for them great vid.

Dear Scott, good job! Frankly speaking, I never believed in the "healing current" for lead-acid batteries.

I have good experience with such a desulphator, but only on batteries that are good in the first place, but which have been completely discharged by 'accident'. Have taken apart many tens of batteries, and most newer types led acid batteries have almost only lead oxide in one of the poles when they have half their capacity left

Creators who upload on a Sunday are the best

Wow this video came out just in time been trying to figure out how to hook my battery to a MOSFET spot welders and the instructions were incomprehensible before this video.

Nice work man😊

You’re always have such neat handwriting

I have had some success using a standard DIY circuit, but using it while charging as well as discharging,. I used a 'wall wart' 12V supply and linked it to the positive rail. via a diode , and added another diode between the positive rail and the battery.

GREAT SCOTT, you have done really a great job as usual, your R&D really help us to learn something new in every video. please made a video of victron serial bluetooth dongle...can v DIY it ? because factory dongle is too much expensive... and i am sure you can make it....hope for the video on this topic... thanks...stay blessed.

You say the 330R resistor is connected to nothing, but you can actually see it is connected between the 555 timer ground and battery ground. Anyway, great video, as always!

I just wanted to point out the other person's PCB you stated that R10 is connected to nothing, it is connected to ground, pin 1 IC & led - as per circuit if you check with the multimeter it is connected. Anyway thanks for all the information you are great 👍👍

Great video as always. It’s interesting, that I see no comments from any farmers. I was raised on a farm and most farmers had a simple desulfator made from nothing more than a rectifier and a run capacitor from and air conditioning unit. You plug one end into 120 vac and connect the other to the battery. This gives you a DC out with a large AC ripple of 120hz which, over time, breaks down the sulfation. This will not work on batteries with bad cells but will work about 50% of the time. Something to remember though…this simply postpones the inevitable. The sulfation doesn’t magically disappear but falls to the bottom of the cells. Unless the battery is flushed this will eventually cause a problem.

Yes, please.. keep calling out these scammy youtube channels!!

Oh god... I remember an Electronics Magazine I bought in the 90's to be able to make a Desulphator. I never got results with it but at the time I didn't have any test equipment other than a simple multimeter. I finally know the answer then.

Add a diode to the 12v rail between 555 and mosfet. Power the 555 with a 15v(watch limit of VCC ON 555 timer) plug pack and it trickle charges the battery at the same time pulsing it higher. I increased CCA and reduced mOhms on two car batteries that weren’t too dead.

I've used a desulfator as a annual or bi-annual maintenance for lead acid battery's but never a "revival" tool. I have had cheap garden tractor batteries last almost 10 years and my wife last battery in her SUV was bought April 2013 and have been anticipating replacement any day now.

thank you for for learning us new stuf!

Reminds me of a saying a long time ago: The designers of battery desulphators knowledge of 555 timer circuit design are inversely proportional to Pb battery electrochemistry knowledge ;)

That 10Kc “frequancy” killed it! 🧐

scott is a great person Respect

When it comes to rechargeable batteries, the best course of action is to, if possible, use a battery management system (BMS), charge and discharge the batteries according to manufacturer or traditional recommendations, and generally take good care of them as to maintenance and testing (best done regularly).

Nice editing Great video

I've ever tried to repair my battery with simple mains voltage capacitive dropper desulfation with only 2 components ( using 5uF cap and bridge rectifier). At the first try it worked well, it noticeably repaired my battery as my motorcycle began to cranck again after doing desulfation, but the battery didn't last for long, it only survived for 1 week and then it dead again.

Hi Great Scott, I love your videos. I would suggest you to do a video about gas sensors because lots on the market are really shitty

Everyone argues about disulfation and nobody mentions the frequancy typo on the commercial charger? Very confidence inspiring...

I bought a battery charger with a function that can rejuvenate batteries, and so far it seems to be working. The one battery had a two year warranty, and it was discharged when I bought it for my test. I haven't done load testing on it, but it's holding so far.

Oh, bummer. Let's see the next ideas. Putting them in the fridge doesn't work either! 😬 Thanks for all the testing and video, dude! 😊 Stay safe there with your family! 🖖😊

I think that it could have an positive effect on the CCA of the battery because there isn't sulphate in the way, but there also is the risk of shorting such a big battery!

Based on my tests, desulfation works pretty well on "new" good quality batteries killed by over discharge (in my case it sat in my car for around 60 days while it was parked waiting for me to repair the motor, and the battery was around 3 months old). I did it with an MOSFET, a resistor in series, my bench power supply and function generator, pulsing 20kHz for something around 3 days straight. I can't tell if the capacity was restored to original, but the battery sure started to hold charge again, after that. I used this battery for around a year after that, until I sold the car.

What you need is the old school method! 100w light bulb and a diode! You get a nice half wave ripple of reasonably high current pulses!

I spent a lot of time trying to revive some old batteries connected to a PV system. I learned that if you are trying, the batteries are too far gone, try if you want but expect to replace them. Also never connect car batteries to a PV system. The plates are too weak.

Could not have posted this video at a better time! I'm currently trying to revive a 12V 180Ah lead acid batt. for an off grid type power system, and i cant charge the battery above 13.5V, and it drops to 12.5 if i disconect the charger, and i was about to start making a desulfator, but i guess my chanches are pretty low. So thank you for this video, i researched this topic for hours, and didn't have a clear answer if this is working or not, now i kinda know!

One thing to watch for with lead acid battery capacity testing is the purkett effect. Basically the faster you drain them the less capacity they have by a very significant amount. The name plate rating on them is a 20 hour discharge. It's not hard to hit 50% capacity on perfectly fresh batteries. Not saying that explains the sulphator not working but it's something to watch for when testing lead acid cells.

I'm using desulfator from years and stopped to buy batteries.. i was used to change the battery of my motorbike every 2 years, but now it is 5 years old and still working. my personal experience says it works!

I really like that we live in a time where opinions are equal to facts

I have seen a couple of people attempt to debunk the "MIG Welder battery recovery". It only worked on the non maintenance-free batteries, he was able to dump out the old acid, then filled it up with new battery acid, then hit it with the welder (making certain to observe proper battery polarity) and he hit it just a few times for a few seconds at a time and it was able to recover it to about 90%. The problem is that the battery plates on a normal car battery are very thin and the positive plates are made with a paste of "red lead", and the sulfates causes the paste to crumble off of the plate, and that's what causes them to go bad, as the lead paste will fall to the bottom of the battery and cause a short between the positive and negative plates.