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
Richard, nice charger thank you for the schematic. I do not understand though, how it is a desulfator. Thank you for your further thoughts.
ReplyDeleteMichael C.
Richard,
ReplyDeleteThank 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
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.
ReplyDeleteI 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!
ReplyDeleteI 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.
ReplyDeleteHi Richard,
ReplyDeleteI 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
Richard, would you consider divulging the next step? Maybe in a private email?
ReplyDeleteThanks
michael
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.
ReplyDeleteAny idea how I can make this run on 240v instead of 120v?
ReplyDeleteis there a device one can put in series between a charger and the battery that would create a pulse to desulfate?
ReplyDeleteThanks 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?
ReplyDeleteHi 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.
ReplyDeleteThanks!
without being hooked up to the Battery...it measures 120V DC...is that correct ? or is my Cap no good ?
ReplyDeleteHi richard
ReplyDeletevery 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
Hi Richard,
ReplyDeleteYour circuit looks great and simple. Please advise what to change in circuit for 220 VAC input instead of 120 VAC.
Regards,
Hi Richard,
ReplyDeleteA 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.
Richard,
ReplyDeleteHow much time would be required to desulfate the heavily sulfated 12V 130amps battery using this desulfator.
Regards,
Khalid
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?
ReplyDeleteThanks,
Darrell
Does the capacitor voltage make any difference?
ReplyDeleteThank you
Bill S
Darrell,
ReplyDeleteThe full wave rectifier changes AC to DC with a slight voltage drop.
Bill S.
Hi there
ReplyDeleteTo 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,
Richard
ReplyDeleteI have heared that desufator should have a (resonance) frequency to suit battery structure , could this circuit achieve resonance ?
Richard, I built your desulfator about 6 months ago and it works great. I've rescued many batteries.
ReplyDeleteI'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?