Facebook
Google
GitHub
Linkedin
Lead Acid (SLA) battery desulphation.
- Thread starter recklessrog
- Start date
Thank you for that, but it is the 555 variations that I am dealing with just used as an astable oscillator not connected to the Mosfet.
I have two batches of 555's, one is LM555 and in the same circuit has rise and fall times that are three times faster than the batch of NE555's.
I was surprised at such a difference in the performance so have downloaded the manufacturers data sheets to compare them.
In searching, I came across this useful site
http://www.unitechelectronics.com/NE-555.htm
Yes I did reply to your e.mail, let me know if you received it ok.
Hello,
There are bipolair versions and cmos versions of the 555.
The bipolair version will not reach the full powersupply voltage at the output pin 3, but will stay about 1.5 to 2 volts below that.
The cmos version will have a larger output swing, but can not deliver the current the bipolair can (100 mA versus 200 mA).
Bertus
PS again, please reply on the conversation or email.
There are bipolair versions and cmos versions of the 555.
The bipolair version will not reach the full powersupply voltage at the output pin 3, but will stay about 1.5 to 2 volts below that.
The cmos version will have a larger output swing, but can not deliver the current the bipolair can (100 mA versus 200 mA).
Bertus
PS again, please reply on the conversation or email.
This is something that’s always interested me. I actually purchased a large desulphator (Wizbang Plus) a few years ago and have tried to recover a couple of car batteries and UPS batteries with it, with mixed results.
It’s good that you are posting results of capacity tests to actually compare the improvements; a lot of reviews of such products are un-scientific - they don’t measure anything and are therefore not very useful.
I have a hypothesis that it might not be the pulsing as such that makes it work, but the elevated voltage and long duration involved. One way to test this would be take a battery that doesn’t respond to normal charging, and try and recover it by forcing a small current (say 0.1-0.2A) through it for 24 hours, at whatever voltage it takes (16V and over?). You can do this with a CC/CV supply or a hobby charger (such as the iMax B6 or the Turnigy reactor in Ni-MH mode, as their Pb mode has a CV limit of 2.4-2.45V/cell).
Thinking about battery chemistry, charging is the process of passing a current through the plates to convert PbSO4 on both plates into PbO2 (on the positive plate) and Pb (on the negative plate). Since PbSO4 is not very electrically conductive, it becomes difficult to force enough current through it at normal charging voltages and a higher voltage is needed to get an appreciable current to flow. Since the conversion of lead sulfate to lead oxide and lead requires current, I would think a desulfator on its own (without an external power supply as you used) would not work, as from thermodynamics we know it takes a net flow of current in the charging direction to actually convert any quantity of sulfate into active material. A desulfator connected to the battery alone (no external power source) will actually sulfate the battery more, as the net current flow is out of the battery, discharging it.
Can you tell us the max voltage output by your maintenance charger that was unable to charge the sulphated batteries? My guess is it was probably below 15V.
It’s good that you are posting results of capacity tests to actually compare the improvements; a lot of reviews of such products are un-scientific - they don’t measure anything and are therefore not very useful.
I have a hypothesis that it might not be the pulsing as such that makes it work, but the elevated voltage and long duration involved. One way to test this would be take a battery that doesn’t respond to normal charging, and try and recover it by forcing a small current (say 0.1-0.2A) through it for 24 hours, at whatever voltage it takes (16V and over?). You can do this with a CC/CV supply or a hobby charger (such as the iMax B6 or the Turnigy reactor in Ni-MH mode, as their Pb mode has a CV limit of 2.4-2.45V/cell).
Thinking about battery chemistry, charging is the process of passing a current through the plates to convert PbSO4 on both plates into PbO2 (on the positive plate) and Pb (on the negative plate). Since PbSO4 is not very electrically conductive, it becomes difficult to force enough current through it at normal charging voltages and a higher voltage is needed to get an appreciable current to flow. Since the conversion of lead sulfate to lead oxide and lead requires current, I would think a desulfator on its own (without an external power supply as you used) would not work, as from thermodynamics we know it takes a net flow of current in the charging direction to actually convert any quantity of sulfate into active material. A desulfator connected to the battery alone (no external power source) will actually sulfate the battery more, as the net current flow is out of the battery, discharging it.
Can you tell us the max voltage output by your maintenance charger that was unable to charge the sulphated batteries? My guess is it was probably below 15V.
Hi Thank you for the interesting input.
In my first post, I did mention that a couple of the batteries would not accept any charge. I connected one to a 60 Volt variable voltage, current limited power supply and after 24 hours, still no current was flowing.
I connected the Dave Barker design De-sulphator Via a 20Watt 1 ohm resistor and supplied it from my 5amp bench supply set at exactly 12volts for 24 hours and by using differential measurement with the 'scope measured that it was putting 20 amp pulses into the battery. (peak pulse voltage can reach over 250 volts p.p)
Several more cycles of charge/discharge with the de-sulphator have so far brought that battery up to nearly half it's rated capacity.
As this is still all on going, I am not yet able to say whether or not I can get any more improvement, but given time, once I have concluded all the refinements to the circuit and run enough cycles until there is no further improvement to a number of the batteries, I will try and draw some graphs for individual batteries. At the moment, I am logging, Original state, start time and voltage, charge time, discharge time at given loads to cut off, then repeating.
Because the two de-suphators I have built so far are working well, I am keeping them as shown for the tests otherwise it would confuse results if I make any changes to them. Having said that, I am experimenting with a third version and different batteries, refining and monitoring performance with some tweaks to the MK11 design. So far, the actual effect seems to be fairly tolerant of components used and are relatively non critical.
P.S. The maintenance charger has a maximum of 14.6 volts, then drops to 13.6 float charge.
Last edited:
That's interesting that the 60V supply was not able to revive the battery but the desulfate was. That's one against my hypothesis because it seems that pulsing is doing something a high DC voltage alone isn't capable of doing. Or it might be that the higher peak voltage (200V vs 60V) is doing all the magic and a 200V DC supply would work just as well. Hmm.
I had a UPS battery that read zero volts on the output. No amount of constant current and desulfation would get it to hold open circuit voltage of over 5 volts. My experience is that the higher the resting voltage, the more likely the battery is to recover. If it reads 12V it'll probably live... if it's at 10.5V you have one dead cell. At 9V you have multiple dead cells.
No surprise that your charger didn't do anything, it would probably take weeks to break down the sulfate at 14.8V.
Some interesting data for you: I recently got a 20 amp hobby charger with internal resistance measurement. On an old but healthy 70Ah car battery, the IR is just 40 milliohms for the whole batt when fully charged. When I discharge 17Ah out of it, IR increases to the region of 150mOhm, and it's only after 3-5Ah have been charged back into it that the IR starts falling again.
So one way to track the progress of the desulfation on sealed batteries where specific gravity is impractical to measure may be to take IR measurements as the process progresses.
I had a UPS battery that read zero volts on the output. No amount of constant current and desulfation would get it to hold open circuit voltage of over 5 volts. My experience is that the higher the resting voltage, the more likely the battery is to recover. If it reads 12V it'll probably live... if it's at 10.5V you have one dead cell. At 9V you have multiple dead cells.
No surprise that your charger didn't do anything, it would probably take weeks to break down the sulfate at 14.8V.
Some interesting data for you: I recently got a 20 amp hobby charger with internal resistance measurement. On an old but healthy 70Ah car battery, the IR is just 40 milliohms for the whole batt when fully charged. When I discharge 17Ah out of it, IR increases to the region of 150mOhm, and it's only after 3-5Ah have been charged back into it that the IR starts falling again.
So one way to track the progress of the desulfation on sealed batteries where specific gravity is impractical to measure may be to take IR measurements as the process progresses.
I think it would be unwise to just connect 200Volts to the batteries, the short pulses limit the dissipation of heat and a continuous 200 Volts would very soon lead to disaster. I am not convinced that it is the ring pulse frequency that Dave Barker says is close to the molecular resonance of the sulphate crystals, I'm more inclined to think it is the high voltage/ current pulses that are doing the business, but hey, I'm not a molecular chemistry scientist so will keep an open mind on that. If anyone has conclusive proof of that, I would be glad to know it.
Yes, exactly. My theory is that a small constant current of say 100mA is what it takes - and it might take 60V or 200V to achieve that flow in a very badly sulfated battery, which voltage then decreases as the battery IR decreases.
Some time ago I did try to recover a sulphated battery by putting a higher voltage across it until I got some current flowing, but the end result was disappointing, it never really regained any useful capacity and the initial improvement very soon wore off. That could have just been that particular battery and it may not have been any better with using the de-suphator, although my current procedure does seem to be very promising.
Thanks Eric, I have some LM555's and they all under 20nSec while the NE555's are all around 3 times that. so still playing around with buffers.
Sorry for being slow, I will have to boot up my desktop computer and open my e.mail and re-send the e.mail reply. (the password is remembered by the P.C so I can't log in from here) I'm not at home at the moment, using this laptop mobile. I did list what would be of use, but can't remember off the top of my head which.
hi r rog, i have recently been playing with a few old truck batteries
i tried pumping upto 16V @ 5A into them for up to 10 hrs with no gain in capacity. although, a lot of experts say 'you can't reverse sulphation' , i believe it should be possible , if the lead is not worn out/depleted [for want of a better word] .maybe lots of current can help or even cure this problem hopefully , as i am very sure most batteries get discarded from undercharging , leading to a early demise . i did read once , where someone used a dc welder to give a battery a few short, high amperage charges with some success , but never took much notice . maybe?
I too have tried continuous charging at high and low current without much success, however, the very short very high current pulses seem to be effective. The maximum voltage of the short pulse with my MK11 version is in excess of 250 volts
Cockatoo, be careful with that. Lead acid batteries create hydrogen when overcharged and that can explode. The internet is full of pics of exploded lead acid batteries. It spews acid everywhere. Not good if you're standing next to the battery with a welder in your hand.
There are also reports of high current warping the plates and ruining the battery. I think slow charge for a long time is more likely to succeed.
There are also reports of high current warping the plates and ruining the battery. I think slow charge for a long time is more likely to succeed.
yes , i have had a battery explode when i was young , while welding next to it , i was knocked over and splattered with acid . i was lucky i had all protective gear on. nothing left , but the battery base and a bit of the lead plates at the bottom
Update on the reclamation of the 17 Ah Yausa battery that had recovered about half of it's full capacity.
I decided to prise the cover off and see if it would accept some distilled water in case any cells had dried up.
I found this article....... www.thebackshed.com/Forum/.../2012-03-20_011702_pc_rejuvenate_gelcell_2.pdf ,
and after taking suitable precautions, followed the instructions. All the cells quickly absorbed over 5ccs of distilled water and the one nearest the Positive terminal took about 15cc's.
Prior to doing this, it had reached the trickle charge change over point of the maintenance charger and was at float current of 50-60 milliamps at 13.6 Volts.
Having left it to stand and absorb some liquid, I put it back on the charger where it went to normal high charge of 850 milliamps for a further 7 hours before it resumed float level which was now 13.7Volts.
A discharge test at 5Amps initially maintained 12.5V down to 12.2V over 2 hours, dropping to 11.5V (having reset the current to 5 Amps) over the next 30 mins. then it slowly dropped to 10 volts with proportional reduction in current over the next twenty mins. after which the test was concluded.
All this improvement from a previously scrap battery!
I think that It is a combination of both De-suphation and topping up the electrolyte, neither one one their own being totally the cause of the success.
Today, I was given another ten gell batteries, and as before, some are dead, some are low, and 2 are like new. More testing to follow
I decided to prise the cover off and see if it would accept some distilled water in case any cells had dried up.
I found this article....... www.thebackshed.com/Forum/.../2012-03-20_011702_pc_rejuvenate_gelcell_2.pdf ,
and after taking suitable precautions, followed the instructions. All the cells quickly absorbed over 5ccs of distilled water and the one nearest the Positive terminal took about 15cc's.
Prior to doing this, it had reached the trickle charge change over point of the maintenance charger and was at float current of 50-60 milliamps at 13.6 Volts.
Having left it to stand and absorb some liquid, I put it back on the charger where it went to normal high charge of 850 milliamps for a further 7 hours before it resumed float level which was now 13.7Volts.
A discharge test at 5Amps initially maintained 12.5V down to 12.2V over 2 hours, dropping to 11.5V (having reset the current to 5 Amps) over the next 30 mins. then it slowly dropped to 10 volts with proportional reduction in current over the next twenty mins. after which the test was concluded.
All this improvement from a previously scrap battery!
I think that It is a combination of both De-suphation and topping up the electrolyte, neither one one their own being totally the cause of the success.
Today, I was given another ten gell batteries, and as before, some are dead, some are low, and 2 are like new. More testing to follow
Sounds promising! I never had much luck watering sealed batteries, I suspect I added too much water or my batteries had non-repairable damage.
In the interest of science, could you do a little experiment on the new batch? Start by charging them only, and test. Then add water, charge, and test them. Finally, desulfate them and post the results.
Like that we might be able to get an idea of how much of the improvement is due to charging, how much due to watering, and how much from the desulfator. Would be really interesting to see isolate the results like that.
In the interest of science, could you do a little experiment on the new batch? Start by charging them only, and test. Then add water, charge, and test them. Finally, desulfate them and post the results.
Like that we might be able to get an idea of how much of the improvement is due to charging, how much due to watering, and how much from the desulfator. Would be really interesting to see isolate the results like that.
Yes I had been thinking along the same lines, trouble is with only two chargers, two de-suphators and one load it may take a while.
I am going to make cutoff point switch for the discharge cycle so that when the batteries reach 10.8 volts (as recommended by Yausa) the discharge and record are terminated. I have a Tenma 72-1016 multimeter that has software to record the voltage over time on a laptop using the audio record input, a very useful feature.
Oh, I forgot I was going to post some info on the choice of inductor, although I have found that if you have a switching transformer from an old plasma tv power supply, find a heavy gauge winding and most seem to work as long as they are between 200 to 450 micro Henries. I will post some pictures soon.
