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The Magic of Desulfation: Can an Old Lead Acid Battery be Revived?
Now this is an old car battery of mine; but why does that matter? Well, some time ago a viewer sent me a link to a YouTube video. In it, someone took an old lead acid battery with little capacity left, built a magic circuit for it which he then slapped onto it for 30 days and afterwards the battery was said to have gained significant capacity.
I decided to test this claim using my own experiments. I started by creating a more powerful version of the original circuit, which I designed using the Altium Designer software. With this new design, I added a switch to separately turn off the power electronics and also utilized an N-Channel MOSFET instead of a P-Channel one.
The next step was to upload my design to JLCPCB to order professional PCBs for a very low price. Currently, they offer 1-8 Layer PCBs for only $2 and even their 1-20 layer PCB assembly service also comes with $24 coupons. I received my PCBs within a week and they looked gorgeous.
It was time to add all the components to my board, solder them in place, and ultimately take it for a test ride. Unfortunately, I made a big mistake. Since I am now using an N-Channel MOSFET, the on time of the waveform turns the MOSFET on and that is problematic because in this 555 timer configuration the on time can only be above 50% of the duty cycle. Sounds a bit complicated but it basically means that the MOSFET stays on for too long and thus too much current flows through the coils.
To fix this issue, I had to come up with a little logic level inverter circuit which looks something like this in the schematic. With it, the on time of the MOSFET once again gets dictated by the off time of the waveform and thus everything now works perfectly fine. And since the on time is quite a bit longer than the original circuit ones, it not only draws a bit more current in direct comparison but its current pulses are also more powerful.
I decided to conduct a 30-day experiment with two batteries, where I would daily charge up the small battery. As soon as the 30 days were over, I charged up the batteries once more and as you would have expected, they discharged them with the constant load. The result of the smaller battery was that the capacity stayed pretty much around the same. For the bigger battery, I was pretty much the same deal, bummer.
I also tried out commercial Desulfator circuits from Amazon to see if their results were any different. The first one pretty much works the same way as my DIY one, but the second one seems to use a higher frequency. I did another test with them for two weeks, but sadly, the results were even worse this time because the capacity of both batteries apparently shrank noticeably.
I am not entirely sure why this happened, but I have to accept this result meaning that all in all, the circuit from the video was real; but according to my tests and experiments, Desulfation is not, at least according to my results. Feel free to believe whatever you want and keep in mind to be respectful in the comment section.
I hope you enjoyed this video and learned something new. Don't forget to like, share, subscribe and hit the notification bell. Stay creative and I will see you next time.
WEBVTTKind: captionsLanguage: enNow this is an old car battery of mine; butwhy does that matter?Well, some time ago a viewer sent me a linkto a YouTube video.In it someone took an old lead acid batterywith little capacity left, built a magic circuitfor it which he then slapped onto it for 30days and afterwards the battery got allegedlyrevived with close to its original capacity.For me that all sounds too good to be trueand there were actually 2 big things in thevideo that made me question whether it isfake or not.The first one and most obvious one was thatthe capacity of the battery never got measured,neither before nor after using the magic circuit.And secondly; in the creators schematic andfinished PCB design you can find a resistorthat is connected to absolutely nothing, whichmade me question whether he knew what he wasdoing.So in this video I will put his circuit andthis battery revival technique to the testwhich of course includes proper capacity measurementsand own designs to ultimately declare whatis real and what is fake.Let's get started!This video is sponsored by the Altium DesignerSoftware and JLCPCB, who are a perfect matchwhen it comes to designing PCBs and then actuallyordering them, but more about them later.Now first off, this method of reviving batteriesis called Desulfation and it is limited tolead-acid batteries which you can find inyour car, motorcycle or even alarm systemsas a backup battery.You can find tons of information about Desulfationand opinions about whether it works or noton the internet.But to summarize it briefly we can say thatwhen discharging a lead acid battery, leadsulfates accumulate on the plate electrodes.Do not worry though, because when chargingup the battery, those sulfates disappear.But if your battery got not used for a longtime, got discharged too much or had to handlebig temperature differences then those sulfatecrystals on the plates can increase in sizeand stay there permanently which decreasesthe current the battery can output and alsomore importantly its capacity.To solve this problem people came up withthe Desulfator circuit that in a nutshellcreates high current pulses that breaks downthe crystals and removes them from the plates.And with the initial theory out of the wayI wanted to firstly see what my old car batterycan still output.So I charged it up to 14.8V with my lab benchpower supply and in case you are wondering,that is pretty much the max voltage you shouldcharge a lead acid battery with.I also set the max current to 7A which isone tenth of the original capacity and thatis a pretty good rule of thumb when it comesto careful charging or discharging.But anyway, as charging was going I sensedthat something was wrong because it took foreverfor the charge current to settle down, thebattery was getting a bit warm on the outsideand the initial voltage of 10.3V only increasedup to 11.4V and was dropping quickly.Needless to say this battery could no longeroutput any significant current, meaning therewas nothing that could revive it and thusI had to replace it with two other lead-acidbatteries I had lying around.After fully charging them up the same wayas I described it before and then using aconstant load to discharge them while simultaneouslycalculating their capacity, it seems likethe big battery came with a real capacityof 23.94Ah while it originally featured 44Ahand the small one only 2.345Ah while originally4.5Ah.In both cases that is around half of the originalcapacity and since they have been standingaround most of the time doing nothing, theyshould be perfect candidates for a Desulfatorcircuit, right?To find that out I firstly recreated the schematicof the Desulfator circuit from the video inorder to understand how it functions.And luckily for me it is build around a 555timer IC about which I already made a basicsvideo that you can check out for more information.But simply put, the 555 timer outputs a rectanglewaveform on its output whose frequency andon/off time gets set by these two resistorsand one capacitor.Of course you could calculate all of thaton paper but for more fun I simply built this555 timer circuit up in mid air to determinethat it creates a rectangle waveform witha frequency of 1.22kHz and an off time of35us.In this case the off time is more importantbecause that is the time the used P-ChannelMOSFET is turned on in the schematic meaningcurrent can flow through it.When that is happening current also flowsthrough these two coils who not only now letthe current rise slowly but they also buildup a magnetic field around them.And as soon as the MOSFET turns off aka therectangle waveform switches to high, the energyof the magnetic field of the coils now getsused to still pump current through the circuit.But the only way to go now is to the batteryand that is how the current pulse gets created.To test this I built up this exact circuitin midair and after connecting it to a battery,nothing exploded and you can now clearly hearthe 1kHz hum of the coils meaning our currentpulse got created successfully.That means the circuit from the video is realand does its job like intended.But maybe it is not a completely originalcircuit because after doing some researchI found the resistor the video creator usedincorrectly and normally it is used to adda bit of resistance between the 555 timerand the power part of the circuit.But nevertheless even though this circuitworks, I wanted to create a more powerfulversion of it which means I needed to adjustthe rectangle waveform.And while I was at it I also wanted to adda switch to separately turn off the powerelectronics and also utilize an N-ChannelMOSFET instead of a P-Channel one.So with those ideas in mind I created my ownversion of this circuit with the Altium Designersoftware which was quick and easy to do.And while I was at it I also created a PCBdesign for the circuit to make things easierfor me later on.And through the help of Altium 365 I couldalso upload my design to the cloud to accessit everywhere and share it easily; so if youwant to try that out as well then check thevideo description below.OK, the next step was of course then uploadingmy design to JLCPCB to order my professionalPCBs for a very low price which like alwaysarrived within a week and looked gorgeous.Currently they offer 1-8 Layer PCBs for only$2 and even their 1-20 layer PCB assemblyservice also comes with $24 coupons, so definitelycheck them out as well.And with that being said it was time to addall the components to my board, solder themin place and ultimately take it for a testride; only to find out that I made a big mistake.You see, since I am now using an N-ChannelMOSFET, the on time of the waveform turnsthe MOSFET on and that is problematic becausein this 555 timer configuration the on timecan only be above 50% of the duty cycle.Sounds a bit complicated but it basicallyonly means that the MOSFET stays on for toolong and thus too much current flows throughthe coils.To fix that I had to come up with a littlelogic level inverter circuit which looks somethinglike this in the schematic.With it the on time of the MOSFET once againgets dictated by the off time of the waveformand thus, as you can hear, everything nowworks perfectly fine.And since the on time is quite a bit longerthan the original circuit ones, it not onlydraws a bit more current in direct comparison,but its current pulses are also more powerful.And that brings me to my 30 day experimentwith the 2 batteries in which I only had towait and daily charge up the small battery.As soon as the 30 days were over I chargedup the batteries once more and as you wouldhave expected it discharged them with theconstant load.And the result of the smaller battery wasthat the capacity stayed pretty much aroundthe same and for the bigger battery I waspretty much the same deal, bummer.Now please don't start complaining that mycircuit is the problem here because I actuallyalso tried out commercial Desulfator circuitsI got from Amazon.The first one pretty much works the same wayas my DIY one, but the second one seems touse a higher frequency.So I did another test with them for two weeks,but sadly the results were even worse thistime because the capacity of both batteriesapparently shrank noticeably.I am not entirely sure why but I have to acceptthis result meaning that all in all the circuitfrom the video was real; but according tomy tests and experiments Desulfation is not,at least according to my results.But feel free to believe whatever you wantand keep in mind to be respectful in the commentsection.With that being said I hope you enjoyed thisvideo and learned something new.If so don't forget to like, share, subscribeand hit the notification bell.Stay creative and I will see you next time.
