Here is a quick test of the setup and it works well. The computer is an old acer running win XP that I had stopped using, so is ideal for making the recordings. All I have to do now is make the low volt cut off and it's all good to go.
The gaps in the recordings are where I disconnected it to check that it was working ok. I can set the sample rate to suit the battery on test, Low Ah ones probably every 10 or 20 secs, larger capacity ones, once every minute or or longer.

 

Anyone following these post may find this link interesting.
Charging Information For Lead Acid Batteries – Battery University
batteryuniversity.com/learn/article/charging_the_lead_acid_battery/subscribe_thx

 

Another update.
For anyone interested, I have now enough proof that it is possible to rejuvenate some gell cell batteries. My extensive tests show that there is no guarantee that any given battery will recover, but as you have nothing to lose, it's always worth trying. My success rate is around four out of ten that came back to close on new performance, a further 3 better than two thirds, the remainder really are of not much practical use and are scrap.
Of the successfully recovered batteries, on their own, the two methods I used both gave a worthwhile improvement, but combined, led to a high rate of rejuvenation.
Best sequence is this:-...... first off, try to charge from a maintenance charger, then perform a discharge test and note the result. Now following this link....http://www.thebackshed.com/forum/uploads/Bub73/2012-03-20_011702_pc_rejuvenate_gelcell_2.pdf top up the electrolyte and leave to stand overnight before attempting to recharge. Be careful and wear eye protection as a short in a cell can cause the off gassing hydrogen to explode. Re-charge with the rubber caps off and have the battery in a bowl to catch any overflow. Top up any "dry" cells and conduct another discharge test and note the result, there should be an improvement. Now connect the de-sulphator with a 1 or 2.2 Ohm 20 Watt resistor in series and leave it charging for at least 24 hours then check the fluid level again, keep all the cells wet throughout these stages.
Now repeat a discharge test, note result etc and repeat de-sulphator/discharge another 2-5 times, checking fluid after each charge. Finally use the maintenance charger, and you should be able to see a substantial increase in Ah capacity in the next discharge test.
Fully recharge with the maintenance charger. Now is the time to carefully remove any un-absorbed water by using a syringe with a short piece of tube attached (I use a cut down plastic straw) or tip it out into a bowl for safe disposal, clean up any spilt overflow with a wet cloth, and dry the case. Now re-fit rubber caps and lightly glue the plastic cover back on, I use a solvent glue used for joining plastic plumbing pipe.
This may seem a long winded process, but now having a useful battery is better than scrapping it.
I should mention that if you have a battery that will not accept an initial charge, connect it to the de-sulphator for 10-24 hour with the resistor in series and then you should find it will accept a charge, so proceed as above. Also, if after two or three attempts no improvement is detected, then it is a scrapper.

I hope this series of posts has or will be of use to someone, and if you have any questions or observations, I would be pleased to hear from you

 

Thank you for posting the procedure . Can you give details of the discharge parameters (current and end voltage)? Have you had any success without the de-sulfator? Also, for the ones that failed to revive, what were the symptoms? Did you try a high voltage (say, 30V) at very low current (say, 0.1A)?

 

Hello,

@recklessrog , the link in your post does not work.
Did you mean to use this link?
http://www.thebackshed.com/forum/uploads/Bub73/2012-03-20_011702_pc_rejuvenate_gelcell_2.pdf

Bertus

 

Thank you for posting the procedure . Can you give details of the discharge parameters (current and end voltage)? Have you had any success without the de-sulfator? Also, for the ones that failed to revive, what were the symptoms? Did you try a high voltage (say, 30V) at very low current (say, 0.1A)?

Ok, give me a little time and I will try and quantify the results, and yes I have tried many other methods without much success, this procedure seems to be far more consistent in recovery than any others I have attempted in the past including a higher voltage, low current etc. As I stated in one of the posts, the very short high energy pulses seem to be the key along with the fluid top up. Oh and resting time too helps.

 

Hello,

@recklessrog , the link in your post does not work.
Did you mean to use this link?
http://www.thebackshed.com/forum/uploads/Bub73/2012-03-20_011702_pc_rejuvenate_gelcell_2.pdf

Bertus

Oh thank you i will repair the link .

 

Hello,

@recklessrog , the link in your post does not work.
Did you mean to use this link?
http://www.thebackshed.com/forum/uploads/Bub73/2012-03-20_011702_pc_rejuvenate_gelcell_2.pdf

Bertus

Thanks, I have repaired the link

 

LMF5000 - did you use the method mentioned by you - small current at nicd battery setting, charging lead acid battery with higher voltage with reactor or similar all chemistry charging?

 

LMF5000 - did you use the method mentioned by you - small current at nicd battery setting, charging lead acid battery with higher voltage with reactor or similar all chemistry charging?

Yes I did. In NiCd/NiMH battery mode, it operates on constant current - regardless of the voltage needed to achieve said current. I had a destroyed UPS battery (cracked case, about 1.5V open-circuit voltage) where setting a low 0.1A current resulted in the charger pumping over 30V into the battery just to get 0.1A to flow.

The reaktor/antimatter allows setting of custom per-cell voltage (not all hobby charger do this - my very old iMax B6 for example does not). For lead acid, the default is 2.40V but I increased it to 2.47V to give 14.8V for fully charging maintenance-free car batteries with calcium/calcium grids (I got the 14.8V value from here: http://jgdarden.com/batteryfaq/carfaq9.htm ). I suggest switching to this mode once current starts to flow, as it provides the extra safety of a limited max voltage that the Nixx modes do not (though, at 0.1A current the maximum power flow will be around 0.1A x 30V which is only 3W, so not much heating potential).

For equalizing at 15-16V I use the Li-Ion mode, set to 4 cells (obviously not with any balance mode since lead acid batteries do not come with balance taps). Li-Ion default voltage is 4.1V/cell (and Li-Po default is 4.2V/cell), so 4.1x4 = 16.4V max, which would be a little on the high side for equalization, but can be adjusted down to suit.

 

thanx for detailed answer, just one little detail - was there some measurable result?

 

thanx for detailed answer, just one little detail - was there some measurable result?

I tried on two ups batteries. One had a terminal voltage of 10.5V when I got it. I was only able to get it to take some appreciable charge current after opening the caps and injecting water, but it never really stored much charge. One of the cells kept getting hot and the terminal voltage would fall to 10.5V after a day. I suspect it had a shorted cell.

The other UPS battery read almost 0V. Current would hardly flow. I added water but it just leaked out through cracks in the case when charging. It never really recovered appreciably either, and I recycled it when it wouldn't stop leaking.

I am realising now that I was being impatient, trying to force huge currents into these batteries and giving up after a few days. Next time I get a bad battery I will try a very low current (0.1A) and give it a week or more - perhaps it will gently dissolve the sulphates.

 

I tried on two ups batteries. One had a terminal voltage of 10.5V when I got it. I was only able to get it to take some appreciable charge current after opening the caps and injecting water, but it never really stored much charge. One of the cells kept getting hot and the terminal voltage would fall to 10.5V after a day. I suspect it had a shorted cell.

The other UPS battery read almost 0V. Current would hardly flow. I added water but it just leaked out through cracks in the case when charging. It never really recovered appreciably either, and I recycled it when it wouldn't stop leaking.

I am realising now that I was being impatient, trying to force huge currents into these batteries and giving up after a few days. Next time I get a bad battery I will try a very low current (0.1A) and give it a week or more - perhaps it will gently dissolve the sulphates.

That is where the de-sulphator scores, I found several batteries that improved to around half the rated Ah capacity by just adding water then a slow low charge, but after a discharge cycle, leaving on the de-sulphator for 24-48 hours and repeating another discharge/charge with de-sulphator, the Ah capacity on twof them is as good as new! Some others that by only adding water and slow charge, also gained a considerable increase in capacity. As my tests have shown, the best results I obtained were by a combination of both.
I also found that forcing a constant high current only damaged the battery further. probably warping the plates as well.

 

That is where the de-sulphator scores, I found several batteries that improved to around half the rated Ah capacity by just adding water then a slow low charge, but after a discharge cycle, leaving on the de-sulphator for 24-48 hours and repeating another discharge/charge with de-sulphator, the Ah capacity on twof them is as good as new! Some others that by only adding water and slow charge, also gained a considerable increase in capacity. As my tests have shown, the best results I obtained were by a combination of both.
I also found that forcing a constant high current only damaged the battery further. probably warping the plates as well.

I have a 42Ah car battery that only gives 9Ah (repeatedly) on discharge cycles down to 10.5V. I've had it hooked up to a de-sulfator for almost a week. This weekend I will test the capacity again to see if it's improved.

How are you de-sulfating the batteries? Do you do it with them charged or discharged? And do you have the charger connected to the battery as well while the de-sulfator is running?

 

I have a 42Ah car battery that only gives 9Ah (repeatedly) on discharge cycles down to 10.5V. I've had it hooked up to a de-sulfator for almost a week. This weekend I will test the capacity again to see if it's improved.

How are you de-sulfating the batteries? Do you do it with them charged or discharged? And do you have the charger connected to the battery as well while the de-sulfator is running?

Always de-sulphate from discharged. As it can take 36-48 hours of repeated charge (with de-sulphater) to recover a 7Ah gell battery, I would think maybe a week of two for a 45Ah battery. Do not just leave it on without running discharge cycles though.
If you read through the posts from no.1 you will see how It was done and all the experience I gained from it

 

Always de-sulphate from discharged. As it can take 36-48 hours of repeated charge (with de-sulphater) to recover a 7Ah gell battery, I would think maybe a week of two for a 45Ah battery. Do not just leave it on without running discharge cycles though.
If you read through the posts from no.1 you will see how It was done and all the experience I gained from it

Well, to be honest with you I used to do it with charger connected but the charger developed started buzzing from it after some weeks. I strongly suspect the high voltage from the de-sulfator caused some arcing in the charger's transformer windings and burnt some of the insulation, so I'm trying to avoid putting any chargers across the battery while it's de-sulfating. These days I use more advanced hobby chargers with DC-DC topology instead of the old magnetic one that developed the buzz, but they still use an output capacitor with a rating lower than what a de-sulfator can produce, so I'm not sure it's worth the risk. I will review your methodology as soon as I finish writing this post .

 

Well, to be honest with you I used to do it with charger connected but the charger developed started buzzing from it after some weeks. I strongly suspect the high voltage from the de-sulfator caused some arcing in the charger's transformer windings and burnt some of the insulation, so I'm trying to avoid putting any chargers across the battery while it's de-sulfating. These days I use more advanced hobby chargers with DC-DC topology instead of the old magnetic one that developed the buzz, but they still use an output capacitor with a rating lower than what a de-sulfator can produce, so I'm not sure it's worth the risk. I will review your methodology as soon as I finish writing this post .

Sounds like a badly designed de-sulphator, there is nothing fed back to the charger from either circuit I built. The input shottky diode takes care of that.The power supply in my Mk11 version can supply around 2 Amps at 12 volts which is more than required for the inductor/capacitor to easily produce the 50 + amp pulses that are doing the work. (open circuit there are 250 volt peaks) They are so short that there is negligible heating of the battery. I put 2.2 Ohm wire wound 25w resistor in series with batteries up to 7 Ah, and 1 Ohm with 17 Ah batteries. They are low inductance wound resistors, but normal w/w resistors seem to work just a well.

 

I was using a commercial off-the-shelf de-sulfator (my model was called the wizbang plus, they don't make it any more). The desulfator does not have the charger built in like yours does, it is powered solely by the battery. I was using a regular car charger (Absaar 8 amp model) connected across the battery at the same time.

The wizbang plus didn't help the capacity of this battery. Now I bought a cheap capacitor-based desulfator from eBay and I'm trying that for a week. So far only the de-sulfator is connected across the battery, alone, using the battery's power to generate the pulses. Terminal voltage has been 13-13.1V all week. Not sure whether it would work better if I put a charger across it too while it's de-sulfating.

I do have some Schottky diodes, perhaps I could put one in series with the charger to protect it from the de-sulfator's high voltage?

 

I was using a commercial off-the-shelf de-sulfator (my model was called the wizbang plus, they don't make it any more). The desulfator does not have the charger built in like yours does, it is powered solely by the battery. I was using a regular car charger (Absaar 8 amp model) connected across the battery at the same time.

The wizbang plus didn't help the capacity of this battery. Now I bought a cheap capacitor-based desulfator from eBay and I'm trying that for a week. So far only the de-sulfator is connected across the battery, alone, using the battery's power to generate the pulses. Terminal voltage has been 13-13.1V all week. Not sure whether it would work better if I put a charger across it too while it's de-sulfating.

I do have some Schottky diodes, perhaps I could put one in series with the charger to protect it from the de-sulfator's high voltage?

Without the schematic, I have no idea of how it is working. Refer to the link I provided in the first few posts regarding the Dave Barker design and the schematic of my Mk11 version. He does give a description of what he believes is going on and why.

 

Without the schematic, I have no idea of how it is working. Refer to the link I provided in the first few posts regarding the Dave Barker design and the schematic of my Mk11 version. He does give a description of what he believes is going on and why.

Me neither, I just bought it and put it across the battery. Here's an example of one like the one I just bought: https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/ulk/itm/281872297166

I can post disassembly pics if necessary, but probably best to see if it works first