A Battery Rejuvenator

[rvcrawford]

J.J.

That math is correct but only if the 100W light bulb is energized with it's rated voltage. The tungsten filament has low resistance at room temperature and increases as it heats.
I just measured a 65W bulb at 16.5 ohms. If it stayed at that resistance it would draw 7.3 amps and would burn 873 watts not 65 watts.

I have no idea how much resistance a 100 watt light bulb would have when connected in series with a half wave rectifier and the impedance of the battery but my guess is that it's less than 144 ohms.

This has been a very interesting thread and I'm going build me one and try it on an old boat battery that I have.

Thanks
Roger

 

[J_J]

Probably, some of you test a battery charger by touching the clips together to see a spark, and if you do, you assume that it is working.

Have any of you came across a battery charger that seem to not put out any voltage? Well I did and thought the charger that I purchased was bad/broke.

A friend of mine showed me something interesting that I did not know. Apparently some battery chargers need some voltage to start the charging process.

The charger reads no voltage not connected to battery, and when connected to battery, it is putting out about 14 V.

Anyway, didn't know if anybody had came across one of these chargers, and thought it was no good, but try connecting the clips on the battery and see if there is any charging voltage.

 

[dcyrilc]

A 100 w bulb, using 120 v AV, will have a current of .83333 amps, and a resistive load 144 ohms.

Three light bulbs will develop 300 W, and use 2.5 amps.

In this circuit, a half wave rectifier is used to rectify the AS voltage to 60 v DC.

So 60 v divided by 144 ohms, is .41 amps through each leg, three legs will draw 1.23 amps, and three bulbs will develop 221 W, and the bulbs will not be as bright.

I believe this correct. If you find mistakes, please correct. It's been a while since messing with electronics circuits

If you short the diode, then you are putting 120 V AC at 2.5 amps on the battery.

Now that I am actually awake and have thought about it. It should be 120V pulsating DC. On a 120V AC circuit the sign wave goes from 120V+ to 120V- referenced to 0V (neutral). The diode will cut off either the + or - half of the sign wave depending on orientation. I believe the purpose of the diode is to prevent the reversing of current through the battery during the second half of the AC cycle.

 

[J_J]

Rectifier circuits : DIODES AND RECTIFIERS

 

[dcyrilc]

Rectifier circuits : DIODES AND RECTIFIERS

Full-wave rectifier, center-tapped design.

This circuit's operation is easily understood one half-cycle at a time. Consider the first half-cycle, when the source voltage polarity is positive (+) on top and negative (-) on bottom. At this time, only the top diode is conducting; the bottom diode is blocking current, and the load sees the first half of the sine wave, positive on top and negative on bottom. Only the top half of the transformer's secondary winding carries current during this half-cycle.


This is effectively what we are doing and only using the first half as 120V AC in the home is one side of a 240V center tapped transformer with neutral being the center tap. Our 1/2 voltage is 120V because of the center tap.

 

[ModMech]

Have any of you came across a battery charger that seem to not put out any voltage? Well I did and thought the charger that I purchased was bad/broke.

A friend of mine showed me something interesting that I did not know. Apparently some battery chargers need some voltage to start the charging process.

The charger reads no voltage not connected to battery, and when connected to battery, it is putting out about 14 V.

My Schumacher is that way, unless the battery has about 1/2 charge voltage, it won't even try

 

[ETpilot]

Well, on the other forum the discussion has turned to this is a potentially deadly thing. They deleted the post on the circuit. I told them to just delete the entire thread.

So this is the only thread on the subject. I have found 2 maybe 3 batteries. Two are old and one has a little life. I am going to test them to see if it is true that they would explode. Sure don't need that. No where except that thread has a possible explosion been mentioned.

I just have to test this theory and see if it is true. So everyone needs to use caution with this.

A battery does have the potential to explode. Mostly it is poor handling and having something sparking nearby. They should be charged in a well ventilated area away from any sparks.

 

[mmurphy]

(removed), you are making me hungry,might get me something to eat before Spot comes around!!!!!:laughing:

 

[greasemonkeyok]

Couldn't you put two diodes in series in the circuit to double your safety factor?

 

[patrick_g]

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?

Right on regarding the sulfate. Your math skills are OK but...

Tungsten filament light bulbs demonstrate a very non linear resistance under varying currents/heating so your application of Ohm's law, however well intentioned is severely flawed.

There is no effective filtering (except the battery.) The effective voltage of the applied sine wave (half wave rectified is not 60 volts. The 60 volts you talk about is off a bit. The battery dc voltage is "BUCKING" at what ever its current state of charge happens to be (say 10 volts) so the bulb will light as if connected to something more like 50 volts.

After rejuvenation, fully charge the battery, pour out the electrolyte, flush all cells with distilled water, filter the electrolyte through acid proof filter material and put it back into the battery. The battery will probably last considerably longer than just rejuvenation and ignoring the sulphate build up.

Long life cells are built with extra room at the bottom so sulphate build up takes longer to be a problem.

Battery minders that keep your battery fully charged but will not charge a depleted battery nor hurt a fully charged one over time are often "on sale" for less than $5 at Harbor Freight. I have at least 4-5 and no problems in several years. If you don't like HF you can get these for $20-$30 at parts stores, Wally World, etc (still made in China!) I personally know of none that have failed and they are popular around here. There use extends battery life and gives convenience of full charged when needed. They do not "boil off" electrolyte.

Pat

 

[MikeD74T]

Probably, some of you test a battery charger by touching the clips together to see a spark, and if you do, you assume that it is working.

Have any of you came across a battery charger that seem to not put out any voltage? Well I did and thought the charger that I purchased was bad/broke.

A friend of mine showed me something interesting that I did not know. Apparently some battery chargers need some voltage to start the charging process.

The charger reads no voltage not connected to battery, and when connected to battery, it is putting out about 14 V.

Anyway, didn't know if anybody had came across one of these chargers, and thought it was no good, but try connecting the clips on the battery and see if there is any charging voltage.

I occasionally use a 450 amp jump start pac to run a 12v pump. In order to get power out of the pac through the cables that normally go to the battery they must see some voltage from the battery. To supply that voltage I use the cigarette lighter adapter (on the power pac) with 2 small aligator clips to put voltage (from the pac) to the main clamps in parallel. With the pump switch on momentary contact is enough to get it running & pump will keep running until shut off then voltage must be reapplied to restart. MikeD74T

 

[Treemonkey1000]

Couldn't you put two diodes in series in the circuit to double your safety factor?

This whole thread is a fun read. As far as Safety factor just put a 2 amp fuse or whatever value you want in series. Me being the Safety geek that I am will wait until more info has been shared. Keep in mind charging does create volatile gases for these batteries. Safety glasses and good rubber gloves....

 

[ETpilot]

This whole thread is a fun read. As far as Safety factor just put a 2 amp fuse or whatever value you want in series. Me being the Safety geek that I am will wait until more info has been shared. Keep in mind charging does create volatile gases for these batteries. Safety glasses and good rubber gloves....

I was just thinking about a fuse. I am going to get a fuse holder and test with different value, 2 amp and down, fuses. I didn't mention it but I almost always use a GFCI when I work. I do run this charger thru a GFCI.

I never really had a concern using this charger until that other thread. It just has be thinking safety wise. I believe tomorrow I can put the test to the theory. It will be interesting to see what happens.

 

[J_J]

So, what are your plans? Will you remove the diode and use the light bulbs as a load in series with the battery. Otherwise, you will be putting 120 V AC to the battery, using three light bulbs, at a current of 2.5 amps, for how long?

What kind of voltage do you think you will read with a meter, AC volts, or DC volts, or a mixed up voltage.

Only light bulb will allow .833 amps to the battery.

 

[Mickey_Fx]

Have been reading this thread, sometimes with a smile on my face and other times just shaking it over some of the comments. Where does the comment about a battery increasing it's resistance as it gets charged come from. That's just rubbish. Give it some thought, that is saying a battery is least able to supply current when fully charged and can supply more current as it discharges. That's just crazy.

As for this "project", I wouldn't get within a 100' of it in operation.

De-sulfating LA batteries is a valid thing and one can find a lot of info on the net. Commercial products can be bought for fairly low cost. Here is one, Home Wizbangplus. Good qlty parts and construction and uses a well known circuit as it's basis. I have 2 of them, paid $25 on E-bay. They do work and are safe. Did an instrumented test on 2 old batteries. Doubled the capacity but still way short of a new battery.

 

[mmurphy]

I have a battery charger that is all of 25 "American Made" years old, and it will take a battery from dead to start charging with in a half hour. Apears technology got in the way again. As far as circuit and everyones analysis on the proper OHMS law of it, I am hoping someone trys this and puts in on U tube. I do see alot of dangers in it, but than again I can go to a safety meeting for work than when we turn around the same old unsafe habbits apply. As far as a 2 amp fuse protection goes it will only protect the materials not the person. So play it safe, do not come in contact when it is plugged in.

 

[user.69169]

(removed), you are making me hungry,might get me something to eat before Spot comes around!!!!!:laughing:

No need to be concerned about Spot, he's still making his rounds of the neighborhood, just sort of detours around my place for some reason. This morning as he was makin his rounds I stood callin him with 2 biscuits in my hand, but that boy wouldn't come near me for some reason. I got a real strong hunch he got charger bit.

Speaking of hungry, I just had a nice peanutbutter & dill sammich. The combination sounds strange but Birdie introduced it to me when she was with child, and I'll tell you it is gooooood. I like mine on pumpernickle bread slather the pb on both slices slap dill on top of one and assemble that sammich. Now don't get confused thinkin peanutbutter & pickles, I don't care for that at all, just use the dill leaves.

Speakin of pickles has anyone ever had a battered deep fryed pickle, those are some good eating too.

I'm still researchin microwaving the tractor battery, and I'd appreciate some help from you fellows.

 

[J_J]

Have you seen what happens when two metal objects are close together in a microwave, it arcs and sparks. So now, you are planning on putting a battery in a microwave. If there is any hydrogen gas in there at all, I think you will explode the microwave. . What was it that Steven Segal made up and put in the microwave in the movie about the battleship and submarine. Anyway, it blew up his kitchen.

 

[Mace Canute]

Have been reading this thread, sometimes with a smile on my face and other times just shaking it over some of the comments. Where does the comment about a battery increasing it's resistance as it gets charged come from. That's just rubbish. Give it some thought, that is saying a battery is least able to supply current when fully charged and can supply more current as it discharges. That's just crazy.

As for this "project", I wouldn't get within a 100' of it in operation.

I couldn't agree more! Sometimes people playing with electricity should have a bit more technical knowledge than is required to flip on a light switch. This project strikes me as more of a "Here! Hold my beer and watch this!" than a "Mr. Wizard" experiment.

 

[Treemonkey1000]

That's why I am following this thread. Basically your cheap battery chargers are doing about the same thing as this little project. Most cheap battery chargers are putting a pulsating DC into your battery. They are stepping down the voltage from 120 VAC of course. They aren't smoothing the DC pulses out with capacitors or anything. Most of the chargers will current limit themselves when the battery reaches the same voltage as the charger is set up to deliver. At least the cheap ones. You won't catch me hooking up 120 volts to my battery any time soon.