Thursday, May 14, 2009

Updated Charger/Desulfator

With amp and volt readout

by Richard Lewis

Today, I'll be showing you how to make an updated model of my desulfator and charger that you see in my windmill book. This version is nice because it has a pluggin for a simple digital meter and with a flip of a switch you can read the current to the battery, or battery voltage. It also has another switch for a high or low charge current setting. In the below design I used a standard spring loaded speaker wire quick connect box. I used light switches for the on/off and the hi/lo switches. I used a spdt light switch for amps/volts switch. I used a GFCI socket inside instead of an isolation transformer for safety. I also show a pair of 80 MFD capacitors for my high section charging. Actually, it parallels those along with the 24, giving me 184 MFD. That would be about 7.6 amps of charging and about 1 amp at the low setting. You can use some more capacitors in parallel, but remember to make sure your switches, wires, fuse and rectifier can handle the current. The fuse should be just under what the rectifier can handle. If you hook the battery up backwards, this fuse will blow instantly. I used 25 amps for my fuse because I had a 30 amp full wave bridge rectifier.

Notice the 1/4 inch stainless steel bolt (about 2 inches long). It has to be stainless, not plated or galvanized. And the wire connections must be exactly 1 inch apart.
But it is important to have the current sensing wires connected on the inside, while the current carrying connections should be toward the outside. The sensing wires can be a small gauge but the current carrying wires should be a larger gauge, enough to carry the required amps.

This is your shunt and when you select amps on the switch above, you need to turn your meter to milivolts. A reading of 5 milivolts would indicate 5 amps for example. A reading or 8.9 mV would be 8.9 amps. When you switch back to volts, you will have to turn your meter back to the right range unless you have an autoranging one.

You can see in the picture above that I am set for volts and I'm reading the battery at 12.6 volts.
Here is the plugging on the side for plugging in your meter. It is meant for speaker wires but it works great for this application.

Richard
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58 comments:

  1. Richard, nice charger thank you for the schematic. I do not understand though, how it is a desulfator. Thank you for your further thoughts.

    Michael C.

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  2. Michael,

    Thanks. Well, it rectifies the 60 hz AC and creates a 120 hz DC pulse. If it were a power supply, it would have a large capacitor to smooth out that 120 hz ripple. But this one just goes right into the battery. Those pulses help dislodge the sulfation on the lead plates. Also, it is a constant current device due to the capacitor. If the voltage has to shoot up to 100 VDC just to make that current flow, then it will. At that point, it is a high voltage DC pulser. It can put out up to 170 VDC.

    Richard

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  3. Richard,

    Thank you for the explanation. I will definitely build one. I currently have no tired batteries, but a friends motorcycle battery needs help after sitting for a year, I will let you know how it works.

    Best Regards
    Michael

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  4. I would like to build this circuit but am having difficulty locating the correct value capacitors. What kind did you use? Non-electrolytic? I have access to some electrolytic can type capacitors from an old radio buff I'm friends with. They are multi-section caps that I can parallel to get the right values. 24mfd seems to be the problem value.

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  5. I don't think the capacitor value is critical. For the 24 mfd you could use 16, 20, 22. Your charging amperage would drop a bit, but that is the low amp charging cap so not a big deal in my opinion. The charger I am just finishing up has selectable caps that can be added in parallel. I am using 16, 22, 50, 100. The total is just a bit more than Richard's circuit, and with 16 mfd only it likely will put out about 1/2 to 3/4 amp. If you use electrolytics make sure you wire them the right way, or poof!

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  6. I agree with almost everything that doubleeboy said. The only exception would be the last part. I don't think an electrolytic capacitor would even work in this application. I have never tried though. I always recommend the "Run" capacitors used for electric motors. I've seen anywhere from 2 MFD up to 100 MFD. Just call a HVAC company and ask if they have some used ones they are going to throw out. Every time they replace an electric motor, the new one comes with a new capacitor and they just throw the old capacitor away.

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  7. Hi Richard,

    I finished up the charger a couple days ago. Only battery I have that needs help is a BMW motorcycle battery labeled 25AH 130A 12volts. I have been using either 10 or 20 mfd oil caps. I am charging at .35 or .7 amps. What I don't understand is after several hours the charging voltage drops down to 10 volts or so. Does that mean the battery is heavily plugged with sulfate?

    Thanks
    michael

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  8. Michael,

    The voltage usually starts much higher if the battery is heavily sulfated and then as it blasts the sulfates off the surface, some big pieces may fall to the bottom and short out a cell. It may burn through in a few days and the voltage may start rising again. If not, there are some ways to help burn through that stuff but it is dangerous if you don't know what you are doing. The safe way is to let it keep going for a few more days, if there is no change, just write that battery off. I don't really want to divulge the very unsafe method here. Don't want anyone to get hurt.

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  9. Richard, would you consider divulging the next step? Maybe in a private email?

    Thanks
    michael

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  10. I don't have the slightest clue as to where to start, but I have two cordless drills that are realatively new, but their batteries are totally dead. Do you think they're salvagable? Should I even attempt something like this? I have some mechanical aptitude, but I don't want to hurt myself.

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  11. Well, only if you feel comfortable doing this, otherwise, don't attempt it. If you do, then you need low amps to the rechargeable drill batteries. So, you would need a run capacitor that is about 2 to 7 MFD or so in the circuit. That will give you about 100 to 300 mA. And just charge to the batteries get to the fully charged voltage or until they get slightly warm..then you can give them a break and try again later if they still need work.

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  12. Any idea how I can make this run on 240v instead of 120v?

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  13. is there a device one can put in series between a charger and the battery that would create a pulse to desulfate?

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  14. Thanks so much for the info! I sure would like to know about a desulfator by itself. I saw the $50 desulfator, but from what I have learned here, I should be able to build one, just eliminating the 120v part. Could you share what that circuit would look like?

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  15. Hi Richard, can you show a revised circuit using 220V source and a dedicated Amp & Volt meter? For now, i'll read about what is a run capacitor. I'm very interested in building this,so much simpler than other desulfator circuit using FET's & coils.
    Thanks!

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  16. without being hooked up to the Battery...it measures 120V DC...is that correct ? or is my Cap no good ?

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  17. yeah, that is normal. It has no load, so it goes to full voltage trying to get a set current to flow. Make sure it is off, then hook to the battery. Then turn it back on. Read the voltage then.

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  18. Hi richard

    very nice work , Keep it up

    I want to know How much time is req. to desulfate a lead battery with all cell 1200 gravity. battery is 12 v dc 35 AH

    regards

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  19. Hi Richard,

    Your circuit looks great and simple. Please advise what to change in circuit for 220 VAC input instead of 120 VAC.

    Regards,

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  20. for 220 volts at 50 hz it would work out to about 14.4 MFD per amp. Just use the math on this page http://poormanguides.blogspot.com/2009/10/colloidal-ionic-silver-constant-current.html

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  21. Hi Richard,

    A bit confused here, is MFD means milifarad or microfarad? and what working voltage for the capacitor? How do I know when battery is charged full?

    Thanks.

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  22. Richard,

    How much time would be required to desulfate the heavily sulfated 12V 130amps battery using this desulfator.

    Regards,
    Khalid

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  23. I am a little confused on the bridge rectifier. If I'm not mistaken (I'm still learning) it changes current from 120 volts to 12? If so, then what would be the input/output voltage range?

    Thanks,
    Darrell

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  24. Does the capacitor voltage make any difference?

    Thank you
    Bill S

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  25. Darrell,

    The full wave rectifier changes AC to DC with a slight voltage drop.

    Bill S.

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  26. Hi there
    To those who have 220c AC , I say :
    Use 220/110 v transformer that is used early with old refregerators , this will cast a very good isolation for your own safety,

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  27. Richard
    I have heared that desufator should have a (resonance) frequency to suit battery structure , could this circuit achieve resonance ?

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  28. Richard, I built your desulfator about 6 months ago and it works great. I've rescued many batteries.
    I've seen other desulfators that are hooked up to the battery at the same time as the battery charger. Is it safe to use both at the same time?
    Also, is it safe to leave the desulfator on the battery constantly, does it harm the battery?

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  29. Richard love your stuff. I am putting together this one now. I noticed a post about using start caps. But am a bit lost on the correct installation part. Which direction should the start cap be installed at. My cap has a red dab next to one set of tabs. So would the red end be toward the wall receptacle or the full bridge rectifier?

    Thanks a lot.

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  30. It appears that "Start" capacitors are cheaper compared to run capacitors. I am 16 so I need to save as much money as I can. There isn't anyone I know who I would expect to have these things lying around so I need to buy a couple. Would a "Start" capacitor work fine, or would that cause trouble?

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  31. Richard,
    I am assuming you use stainless steel as it is a resistor right? Or is it not necessary? I'm not going to wire in a meter like in your schematic. Most I will do is use a clip-on ammeter to read the amps. In that case could I just get rid of the stailess steel piece?

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  32. Nice. I built it now, and it is awesome. I just need to do some tests on it to make sure nothing is shorted out, or bad capacitors or something like that, and I need to do a quick amp test with the clip on meter, but after that I'm all set. Maybe the lawnmower battery can be revived afterall...

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  33. hi!
    my name is Harry and i would like to get a few details on the desulfator/charger that you've built.My email is harrybrecher@gmail.com and i would like if you have the time of couse to draw the schematics that i would need for the 220-230 vac power supply.
    anyway thanks for your time and hope to hear from you soon.

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  34. This Looks so easy And Great.....!! I Have Few questions To ask.....For 220v.ac or 110v.ac...we need capacitor marked with 240v.ac or the one with 440v.ac also works??
    Talking about full wave bridge rectifiers so car alternators use same i think...they are single face a.c to d/c or 3 face to d.c....!!
    waiting for answers
    regards

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  35. Rchard.
    am stll confused as how to hookup the cap. I can use any help I can get. cleve34

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  36. Hi..Richard...Thanks for your awesome design!.
    I make 25MFD oil cap, for 1 amp. with transformer 10amps(5amp fuse) from 220 to 110, 35amps rectify (25 fuse) and giving output about 96vdc. i can not reach 120vdc. is it enough to desulfat the battery? so according to your formula A= 2*3.1416*60*0.000025*96v or 120v. =0.9047808 or 1.130976. and should i charge the Amps to follow the label on the battery. ex. cycle use: 7.25 - 7.45v(25˚C)
    initial current: less than 1.68A(25˚C)
    ON Battery 6V,4.2Ah/20HR
    standby use: 6,8 - 6.9V.
    So when i want to desulfat battery, i do calculate using your formula above to make it simple, cause i have 15x2, 25, 30, 35 oil caps, i calculate and pick the nearest Amps. Thank you for your advise. it really help me to recycle battery.

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  37. trying to build desulfator.
    the bridge rectifer needs to be 25a what about the voltage size ,also will a microwave capatior work

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  38. Hi,
    What kind of capacitors should I use?
    I have 220V/50Hz

    I think capacitor should be at least 220V and bipolar type, because it is in AC side?

    Is it safe to use it in 220V (with corrected caps value) or should I use 220/110V transformer?

    Meelis

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  39. Hello and thanks a lot for such an interesting things!
    What would be the schematic for 220V greed and for nicel-cadmium battery of 12V/1A, dead now and unchargable by ordinal way? Does it match for this kind of battery to be renewed?
    Thank you,
    Ali

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  40. I don't have a lot of time to answer questions but for all the ones about using 220 volt ac or what size capacitors to use for the different amps, look here http://poormanguides.blogspot.com/2009/10/colloidal-ionic-silver-constant-current.html

    Also, DO NOT use start capacitors, ONLY USE RUN CAPACITORS! The start caps will just start to heat up and smoke after about 30 seconds.

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  41. How would I build one for a golf cart? My golf cart is six 6-volt batteries, making 36 volts.

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  42. The volts are automatic, you just pick the amps you want and use the right sized capacitors for that current.

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  43. I suggest play with 110v instead of 220v, when you forget and touch the terminal, it hurts (I had a couple times), I don't know if you play with 220v..real bad I think

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  44. How fast recover battery do you have some data ; experience

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  45. what is the time of desulfating battery do you have some data-experience ?

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  46. can I use 25MFD instead od 24MFD and 50Amp full wave bridge rectifier (Grec) instead of 30amp full wave bridge rectifier.

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  47. Here is 220v schematic http://pic.mk/?v=desul220v.
    OR http://pic.mk/images/desul220v.

    OK I figured out. Sorry for I was asking silly Q?
    what happen when you left on new battery/or battery is already charged full? I suppose rectifier will automatically shut down the current.

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  48. where can I gets the parts to make your desulfator... i seen run capacitors and bridge rectifiers....but what volt and current ratings do you get them at?

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  49. @Chuck, I see 330 Volt all the time. The run caps don't have a current rating. The current is limited based on the microfarad rating.

    @Martin, good job! I would measure the output of your transformer in AC and use that in the equation. So it is probably 110 to 120 volts or so. Also, some meters don't read the pulsed DC correctly, so when you measure the completed circuit's output, it is probably close to 170 volts pulsed DC, but you meter is showing less. The only way to be sure is use a different meter or check the AC at the transformer output. Multiply that by 1.4. So, 120 VAC would be 168 VDC.

    Also, 1 amp or so is more than enough. I sometimes use a lot less, just so I don't have to "watch" the battery so closely.

    Richard

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  50. @ Stefan, yep you can go to 25 MFD (they don't make a 24). and you can use a higher amp rated bridge.

    Also, when the battery gets charged, it doesn't stop trying..IT DOES NOT STOP. You have to watch your batteries and make sure they don't overcharge or that you don't boil them dry.
    There is a trick to make them act like a transformer power supply that won't overcharge. Someday, I might post that if I have time.

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  51. @ Stefan, also, make sure the voltage rating of the bridge rectifier can handle your max voltage (170 VDC when you input 120 VAC).

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  52. Richard,
    I purchased you windmill and batteries ebook and you never sent the link to me, only a link on how to sign up for a server service. Can I get some help?!. Thanks,
    Tyler

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  53. Richard,

    Can you please respond to my previous comment?

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  54. Really Good Post!!

    San Francisco Bay Area 220/240 Volt 50 Hz Appliance & 110/220 Volt Transformer/Adapter Specialists.220 volt 50 HZ Microwave oven

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  55. Thanks for a good project that can be made with readily available supplies. I have the whole thing in a cigar box, seems to work. I had to put water in the sealed lead acid UPS type battery, the top pops off to expose rubber caps. Before I added water, the volts were over 100, after adding water the volts dropped to a couple of volts above battery voltage.

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  56. is their an alternative to the MFD capacitors

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  57. Hi Richard, could this circuit be modified to run 12v into it, so it could be used to desulfate your batteries in a 12v solar system?

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  58. can this device function without capacitor?
    Thanks,
    cmc

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