A Battery Rejuvenator

   / A Battery Rejuvenator #1  

ETpilot

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I have read a few threads regarding poor battery performance. Thought I would share this Battery Rejuvenator with the members here. It may help restore weak and old batteries. Like many things, no guarantee but it is worth a try. This new thread will take me a couple of posts to complete. Hope I get it right.

The battery charger schematic was posted on one of my aviation forums and I saved it for future use. When my very expensive 24 volt battery showed weak starting symptoms, I made this charger and managed to restored my battery. I have since restored a few 12V batteries. The charger has no name, I just call it my Battery Rejuvenator. It works on the principle of battery equalization. It may or may not work depending on battery condition.

I am no battery guru but have learned a few things about them. If I misstate anything feel free to correct me. I don't want to confuse nor provide wrong information. First an important warning.

WARNING

With this charger you working with and are applying 120 volts directly to the battery terminals . This voltage, 120V, is dangerous and you must exercise good and safe handling precaution. Always disconnect the circuit before touching, testing or handling the battery or charger. Use at your own risk.



Normal voltage testing with test leads is OK. Just like normal 120 volt home voltage testing.

The battery should be removed, cleaned and placed on an insulated surface. A battery can conduct electricity thru the case. I did not believe this when I first read about it but it is true. In this first picture you can see this. The meter positive probe is held to the positive battery terminal and I am holding the negative probe to the battery case. I am reading 9.10 volts thru the case. Test your battery and see if you may have one that conducts thru the case.

A 12 volt battery has 6 cells. Each cell should be capable of generating 2+ volts. You can check each cell to see what voltage you have and whether the cell is good or bad. To do this you need test leads with alligator clips. I used my spring loaded clips. Cut 2 lengths of wire about 4-6" long. Connect them to the alligator clips to use as probes. Now starting at the positive battery terminal, hold the positive lead probe on the battery positive terminal and dip the negative probe into the electrolyte of the first cell. It should read about 2 volts if it is holding a good charge. Then dip the positive probe into that first cell and the negative probe into the second cell. Do this until you get to the last cell. Each test should show about 2 volts. Another way to test is to hold the positive test probe on the positive terminal and dip the negative probe in each cell in succession. The readings should increase by 2; 2, 4, 6, 8, 10 and 12. If one cell reads out of line with the others you may have a bad cell. This charger may not restore the bad cell. The next 2 pictures shows this cell test.
 

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   / A Battery Rejuvenator
  • Thread Starter
#2  
As a battery is used and discharges a process called sulfation takes place. This lead sulfate coats the battery plates and battery energy is reduced.. Recharging the battery reverses this process. Over time as the battery ages this sulfation sticks to the plates and the battery then has problems holding a charge. This is when you may hear the click of the starter solenoid or the engine makes a weak attempt to start. If you look into the cells of a weak battery you may see this grayish, sulfation, matter that forms over the plates.

I found this on an aviation battery website.

Battery Sulfation In A Nutshell: Sulfation is a natural occurrence in all lead/acid batteries including sealed, gel-cell, and recumbent batteries. It痴 the prime cause of early battery failure and is when the sulfur in the sulfuric acid forms sulfur crystals attach to the lead plates and then act as an "insulation" keeping the battery from accepting a charge. Typical chargers and even "smart or automatic chargers" can not overcome this phenomena and thus the battery is discarded as "not being able to hold a charge". Sulfation occurs far more readily in hot climates where batteries aren't frequently used or kept up to voltage. Sulfation can occur in brand new batteries in as short of time period of a few weeks or a few months. Generally speaking, sulfation is the prime cause of battery failure and loss of capacity especially in aviation.

The key to slowing sulfation is to keep the battery fully charged.


This battery charger seems to reverse the sulfation process, restores the electrolyte and cleans the battery plates.

I do not know how it does it but I can see the results. Also, it seems to know what voltage to apply to the battery. I have used it on both 12V and 24V batteries. It does appear to be for a WET CELL BATTERY ONLY. I am going to test it on a sealed battery when a friend that I have locates a suitable sealed battery candidate. I will run a long extension to the battery and place it in a safe place. I do not want the battery to explode on me. I had a car battery explode on me once while driving down the street.




The battery test.

During our recent Texas snow event, I wanted to have my welder/generator ready in case I needed it. Well the battery just barely, very weak, started the unit. I figured it was lack of use and that I may need to use another battery to start the unit. I did not have to use the unit during the snow event but, later, I did need it to do some welding . By this time I did not get any action when trying to start the welder. When I brought welder to the shop to charge the battery, I discovered that it was not a sealed battery as I had thought but in actuality it was a wet cell battery. When I check the cells they were all dry. The plates were coated with the grayish matter. I had been running this welder all this time without ever checking the battery. I have read that running a battery without electrolyte destroys the battery. This would be a good test for the battery rejuvenator.

In the next two pictures you can see the initial voltage test of my dead battery; just under 10 volts and a load test of just over 3 volts. All that I did to the battery was add distilled water to each cell. I then connected it to the charger. After about 1 hour I was reading close to 12 volts but the specific gravity of the electrolyte was still 0. I just let it charge. After about 24 hours I did another voltage/load test. You can see in the second two pictures that the performance had improved considerably.
 

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   / A Battery Rejuvenator
  • Thread Starter
#3  
Here is a chart that I made for the charge process of this battery. I started on Friday and ended on Sunday. This was 24 hour charging. This charger applies a very low amperage charge over a long time period. My 24V battery took over 70 hours to get the electrolyte back to full strength. I use a 4 ball, floating ball, electrolyte tester to test the battery. They are about $1.00 at Walmart.

NOTE, My chart came out messed up. Basically it showed the day, time, the number of balls floating in the tester and the voltage. You could look at the chart and see how the battery was improving. After 2 days of charging I stopped.

At this point I ended the charge process. The battery plates were clean in 4 cells and 2 cells still had a little build up on the plates. I installed the battery and fired up the welder. I have been using the welder ever since Mar 7, 2010.

Note during the charge process you will see the electrolyte bubbling over and some may splatter out. I would not fill the cells too high just above the plates. I have had to remove electrolyte during the charge process.

I just noticed in posting these pictures that this battery is dated September 2003. You can see it on the battery label by magnifying the picture. Sep and 03 are scratched off. I believe this is date of manufacture but could be wrong.
 

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   / A Battery Rejuvenator
  • Thread Starter
#4  
Now to the heart of the matter. I have to admit I was very skeptical when I first saw this charger. But, to me it was worth a try. I am sure many are wondering what is this magical device. Well, it is a simple device that many can fabricate with material at home. The only special part you need to buy is a 3 amp diode. I purchased mine at Radio Shack PN 276-1144. Actually 2 diodes for $1.59.

3-Amp Barrel Diodes - RadioShack.com

The rest is just an extension cord, a 3 or 4 outlet adapter and 100W light bulbs. You cut one leg of the extension cord, add the diode and alligator clips and you are done. When I soldered my diode and wire I used an alligator clip as a heat sink on the diode. Note that when using the charger, the light bulbs will not light as they normally do. They light with a lower intensity.

The first picture is the schematic. Note that the diode has to be installed with correct polarity. The diode has a silver band on one end. This end goes toward the battery. That is it. For each 100W light bulb you get about .45 amps flowing thru the battery. Just leave it on long enough to get the electrolyte back to full strength. This may take days depending on battery condition. During my first use, I only turned it on while I was working around the shop. I just wanted to monitor it. During the last few times I used it I just let it charge 24 hours.

The second picture shows the diode, the heart of the rejuvenator.

In the third picture you will see my jury rigged charger in use. I never got it finished before a friend found out and had to borrow it. The last picture shows my final setup. I am going to buy 2 more light bulb adaptors and keep it as a set. I may make another charger with the second, spare, diode that I have.

Again, I don't understand how this thing works but I am a believer that it does the job.

Make one and try it out for yourself.

And again heed the warning about working with 120 volts.

I hope this is all clear but if not let me know.

Comments are now welcomed.

As a side note, I just want to post some info on a products that I use for coating the battery terminals and restoring battery boxes. This is just for information.

I use Dow Corning DC-4 to coat the terminals. It seems to work really well. I also use it on oil filter gaskets to keep them from sticking.

DOW CORNING DC-4 COMPOUND from Aircraft Spruce

I use aircraft battery box paint to restore the battery boxes. I also use it on the battery hold down brackets. Just thought I would share

RANDOLPH ACID PROOF BATTERY BOX BLACK PAINT #345 from Aircraft Spruce
 

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   / A Battery Rejuvenator #5  
Neat project, and a nice simple circuit. There are chargers that come with this feature - I believe they are called desulferators. Though your setup is much less expensive.

A question for you. Instead of having a separate extension cord, why not put the diode and alligator clips right in the line on the 3-way adapter?

One other suggestion: if you put the diode part reference number on your schematic diagram, that one diagram would give every one all they need to build the circuit:
"1N5404 3 amp barrel diode, Radio Shack part #276-1144"
 
   / A Battery Rejuvenator #6  
Is that .45 amps as in 450 milliamps? Sweet! Is it even possible to overcharge at that rate? Less than one amp? I guess the bulb acts as a resistor and the diode keeps the polarity going in the right direction. My guess is the frequency(60 hertz) is what takes care of the sulfation. My 12v battery in my car and truck are in need of a try. Come to think of it, the battery in my kubota is going on 4 years old too. Maybe I should give that one a try too. Thanks for the info ETpilot.
 
   / A Battery Rejuvenator #7  
ETpilot,
Any idea what it is that kills a battery which is left for an extended period after being drained? I have several of these which won't recharge. I have two vehicles which kill their batteries that way every year. One is our motorhome and the other is a digger/derick boom truck for the farm. Every year I end up having to buy new batteries for them because the battery went dead and by the time I find it, it won't take a charge.
 
   / A Battery Rejuvenator
  • Thread Starter
#8  
Well, I have to post this to keep all of you informed. I posted this same thread on another forum. A member there challenged me that this is not safe. After some positing back and forth he finally stated that if the diode goes bad or is defective the battery could explode.

I replied that I was going to test his theory. So sometime this week I will see if he is correct. I don't want anyone injured if there is a problem. Also, if this is a problem I want to post it here. I have been using this charger quite a bit and have not seen anything dangerous with its use. I am going the test this. I will post my results here.

To answer some of the question, John_Mc, when I first made this I just made the extension cord with diode. I added the outlets in a different fashion. I then saw the adapter at Harbor Freight and thought that would work better. There are few ways you can make this.

dcyrilc, the way I understand it is that the sulfation coats the plates and the battery cannot accept a charge. The typical chargers we use cannot overcome the sulfation. That is why they sell these special chargers to try to restore these batteries. The best way to keep the sulfation down is to keep the battery charged.


Today I tested my welder battery after a few days of none use. The thing started right up. This battery is 7 years old, I ran the electrolyte dry and it only showed a 3 volt load test. Something is working right.

Any way I will see how my theory testing goes.
 
   / A Battery Rejuvenator #9  
You should state that the diode is what rectifies the AC voltage, into DC voltage. The purpose of the light bulbs is to regulate the current. If you short the diode, you are applying 120 volts AC to the DC battery, and it could cause some damage.

The diode is only using 1/2 of the AC cycle, and if the voltage is 120 AC, then the diode will rectify that to 60 v DC

Therefore, 60 volts is going through the single 100 w bulb, and will pass or limit the current to .506 ma, and is used as a current limiter.

So essentially, what you are doing is applying a higher charging voltage to the battery.

What happens to all that sulfate that falls to the bottom, and shorts out the cell?
 
   / A Battery Rejuvenator #10  
I am active in a number of EV and RE (that's Electric Vehicles and Renewable Energy - solar) forums and have designed and built a number of small validation projects to date using Pb-Na batteries, those most commonly available batteries for starting, lighting and accessory (SLA) and Deep Cycle uses. This does not qualify me as an "expert" at any level, but I have significant experience in batteries, chargers and load controls (studied physics in college).

Sulfation is from STORAGE of an undercharged battery. Typical applications that suffer sulfation are: Light aircraft, golf cart, trolling motor supplies and solar power stations. Electric vehicles also suffer somewhat from this if there is no charging station where the vehicle is parked for long periods (office).

ALL batteries suffer from some level of "self discharge". Therefore, even if the battery is placed into storage (hanger, garage etc) with a 100% charge, it will not be 100% some days, weeks or months later. Unless you provide a constant "maintenance charge" to the battery pack, the cells will begin the process of sulfation formation within about 24 hours of "storage". Battery chemistry is a big factor in how quickly the self-discharge happens. If you have on-board systems that draw even tiny amounts of current this problem gets out of control very quickly. In automotive applications, a measured total "static draw" of 0.20A or greater is considered excessive. Remember you start your vehicles weekly if not daily in most cases! For tractors, construction equipment and other infrequent use applications, the practicle limit for static draw is essentially zero, but it depends on the storage time. If less than a month, some very limited draw is allowed, but if over a month any measurable draw will quickly sulfate the battery (pack).

As J_J points out, removing sulfation from the plates causes it to accumulate on the bottom of the battery case where it will eventually short out a cell. If the sulfation levels are small and the battery is large this can take YEARS to happen. More commonly you get another season from the battery and that's all.

I REALLY appreciate the thread! The desulfator idea does work and it's that they do to "rejuvinate" batteries at used battery stores. They desulfate them, drain off the acid, flush out the sulfated material, filter the acid solution and re-fill the battery. Generally this will get you a battery that is at least 70% of new in terms of life expectancy at 50% of the cost.

You best bet, disconnect your fully charged battery completely during storage.

PS: There is no such thing as a "starting/deep cycle" or "combination" battery. SLA (automotive starting) batteries are tested and rated at 0*F, Deep cycles are tested and rated at 60*F. You either get lots of amps for a short time (600+ CCA), or fewer amps over a longer time 25A for 8 hours = 200Ahr). They are oil and water in terms of design.
 
 
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