I don't know what you think will be the benefit of just one hour of using the device will be, but I'll suggest that you won't notice any difference.

 

Agreed SgtWookie. One WEEK- would be a minimum amount of time before you should expect to see any differences.

If the battery is left on the desulfator for several days you should notice that the fluid becomes cloudy and gray colored. As more days pass this will change and the small bits of sulfate will dissolve back into solution, and at this point the fluid should begin to appear water clear again.

THEN you should use the battery to its proper/designed depletion level(discharge it). REcharge the battery using normal charger and if wanted discharge again. Upon recharging the second time, examine the plates. positive plates should be a chocolate brown color and negative plates should be flat gray. If you see any white pearly spots on the plates - you will know that there is still sulfate deposits and should repeat the whole process.

Desulfating a battery is NOT a one day operation. heavily sulfated batteries can be restored over a long length of time, however, hardened sulfate crystals seldom redissolve completely and instead tend to 'break off' and take bits of active lead plate material with them to the bottom of the battery. Meaning the battery may recover to a usable state, but will NEVER be back to its original capacity due to loss of active material.

 

Sorry I was unclear. I meant I would check it after an hour to make sure the desulfator is not overheating and plug the batteries into the 36v charger to estimate how much power is being drawn by the desulfator.

I am aware that it will be weeks before I see a massive difference but for now I just want to make sure everything is working as it should.

Every part seems to be room temperature, even the 100uf capacitor so overheating is not a concern any more.

Is it standard epoxy that is used to hold components in place or is some special non corrosive putty/glue needed? I would like to more securely hold one of the inductors in place.

 

You can connect a float charger across C4 as I've mentioned before. If your float charger is working properly, the batteries should be maintained at ~13.4v-~13.8v.

You can use epoxy if you'd like. Hot glue works, too - but will soften if your circuit gets toasty. Another possibility is low expansion foam made for window/door frame insulation sold under the trademark "Great Stuff" at big orange and big blue hardware stores. Comes in a spray can.

 

Thanks

I built wires coming out of my desulfator in those two areas for my charger. I have just finished building the float charger using an L200 for voltage and current regulation. The voltage is set at exactly 13.5 volts, the optimal float voltage stated on the side of the batteries, with the current at 0.114 amps.

Would it be a good idea to shield the desulfator as I have read that they can cause interference with other items?

I did want to use the time taken for the normal charger to say the batteries are charged in order to judge the desulfators power needs. It looks like the desulfator raises the batteries voltages. That is my only explanation for it charging them within a minute after being on the desulfator for 6 hours. How would I find out how much power it consumes?

Looks like all I can do now is relax and do nothing. Fantastic

 

Sorry but yet another question.

After plugging the charger into the desulfator I decided to check the voltage at the points where the charger and desulfator meet. The odd thing is that it reads only 12.7 volts, Shouldn't it be at 13.5 volts as that is what the charger should be producing. My best guesses are that the voltage is somehow being dropped by the battery as it is not fully charged or the L200 is dropping its voltage as a load is put on it, which it should not do. Can anyone please clear this up for me as I don't know if something is wrong with the charger?

 

You have a wimpy float charger.

Just leave it on there overnight, and see if there's any difference. The desulfator circuit should be drawing about 8-10mA on average, so your float charger is more than keeping up with the drain.

 

Still, it is more than enough than for the wimpy desulfator design you sent. HEHE

Today I needed to use the batteries so I took them away from their desulfator and put them back into the battery pack. I would say that their capacity has improved in only a few days. Although they still need a lot of desulfating.

The battery voltage increased very slowly and reached 12.9 volts by the time I removed them from the desulfator. I might play around a bit with the current to see how it affects them. Is the fact that I am reading these voltages normal? I would have thought that the charger would hold the batteries at 13.5 volts as they charged but this does not appear to be the case.

I have found it difficult to find information about the technical side of battery voltages being fed into batteries and how they affect the charging process and voltages being read. All I find is sites trying to sell me chargers. Does anyone know any good links with this sort of information? I have a few theories about how it works.

 

Today I needed to use the batteries so I took them away from their desulfator and put them back into the battery pack. I would say that their capacity has improved in only a few days. Although they still need a lot of desulfating.

You should document what your run times are. Try to avoid discharging the batteries too deeply.

The battery voltage increased very slowly and reached 12.9 volts by the time I removed them from the desulfator. I might play around a bit with the current to see how it affects them. Is the fact that I am reading these voltages normal? I would have thought that the charger would hold the batteries at 13.5 volts as they charged but this does not appear to be the case.

If I remember correctly, your float charger has a pretty limited current supply, and you have three batteries in parallel. A typical automotive float charger might have a 1A-2A output capacity. If you could increase your float charger to ~500mA output max, that would probably do the trick.

I have found it difficult to find information about the technical side of battery voltages being fed into batteries and how they affect the charging process and voltages being read. All I find is sites trying to sell me chargers. Does anyone know any good links with this sort of information? I have a few theories about how it works.

Try batteryuniversity.com - also look up the datasheets for your batteries and try to understand the specifications.

 

Guess what? Yet more questions, will they ever end you must be wondering.

I will need to give my L200 a nice heatsink if I bump it upto 500ma. Luckily I chose a 10VA transformer (18 volts) and all other components can take the extra current.

Is the very annoying hum caused by L1 and how is it being caused? I have read that it may be worth shielding it using metal as it can cause interference with some devices. Is it worth my while? Either way I want to put it in a container, maybe this is a good excuse to buy a tin of sweets as many people use them.

I will be testing the batteries again on Tuesday and seeing as they are only small I should see a significant increase in AH by then.

Thank you

 

I will need to give my L200 a nice heatsink if I bump it upto 500ma. Luckily I chose a 10VA transformer (18 volts) and all other components can take the extra current.

Yes, you will need a heat sink.

Is the very annoying hum caused by L1 and how is it being caused?

Probably loose windings. You might try making it more quiet by applying a few coats of clear spray acrylic enamel to hold the windings in place so they don't vibrate.

I have read that it may be worth shielding it using metal as it can cause interference with some devices. Is it worth my while?

Toroidal inductors keep most of the energy inside them. That's one of the reasons they are so efficient.

Either way I want to put it in a container, maybe this is a good excuse to buy a tin of sweets as many people use them.

You might do that. However, the MOSFET might get warm if it doesn't have any cooling. Beware, the drain is connected to the MOSFET tab, and there will be 60v peaks on it.

I will be testing the batteries again on Tuesday and seeing as they are only small I should see a significant increase in AH by then.

Sounds like you're doing OK with it.

I'm not going to be on much (at all) anymore for a while, so if you run into trouble, perhaps someone else will help you out.

Good luck.

 

When it comes to the desulfator you have given me all the help I need. Most of my recent questions have not been critical to the project, more just fine tuning.

I would just like to say how thankful I am SgtWookie for your assistance. I would not have successfully gotten into electronics or built the desulfator without your help and patients when answering my endless questions. For whatever reason you will not be around I hope it goes well.

I did not take cooling into account as the desulfator does not produce a noticeable amount of heat, however it has been in an open ventilated environment. I will add a small heatsink and monitor it to make sure it does not overhead in its box.

Thank you

 

Just to let you know that the desulfator really is working.

They hold 2 to 3 times the amps they did before I started desulfation. Still a way to go but a massive improvement so far.

 

Good to know that you're getting positive (sic) results.

As the sulfation is removed over time, you'll notice less and less amounts of improvement. Just keep going until you notice no further improvement.

During this process, it's a good idea to occasionally subject the batteries to a heavy load occasionally (every few days) to prevent the formation of lead dendrites.

Charge them back up to at least 12.7v each before putting them back on the desulfator/charger combination.

 

Thanks for the extra information.

I use them to power what I think is called a hub motor, a motor in a wheel such as the ones in electric pedal bikes, which is mainly used on Tuesdays and Thursdays. My plan was to leave them in the desulfator from Thursday evening until Tuesday morning. Just to clarify, what would you class as a heavy load and how much of the battery's capacity should be drained?

 

A heavy load is 2C and up, where C is the battery amp hour rating. For very large batteries it is closer to 1C

So for a 7Ah battery, anything 14 amps or more would be considered a heavy discharge.

Batteries that are discharged quickly will not have as large a capacity as they are rated for.

 

Am I correct in the fact that their lower capacity at high current is almost entirely down to resistance? For how long would I need to put them under a heavy load?

Hmmmm I have nothing that can drain them that quickly. About 150w per battery. My only idea is to buy a low value high wattage resistor. Would a drain closer to 1C be acceptable? I don't quite understand how dendrites are caused by desulfation. I thought it was caused by overcharging, allowing batteries to discharge too rapidly or too deeply.

 

The chemical processes which convert the plates into pure lead/lead peroxide and then into lead sulfate then back again during charge and discharge are almost 100% effective. There is very little 'loss' in the chemical transformation.

However, the process has no way to determine WHERE it should deposit the lead and lead peroxide, so over time, the active chemical components are dissolved and re-deposited where ever and not always back in the same place they came from.

Deformation of the battery plates is a result and it grows worse the longer the battery is in service.

 

You could use an automotive headlamp from the breakers' yard. A single-beam headlamp will be rated for around 50-55 Watts. If it's a dual-beam (high/low) and wire the filaments in parallel, that'll be around 100-110 Watts.

 

Oh I seem to have mixed up what dendrites are. I thought it was a green crystalline substance that grows on the battery plates caused by some unwanted chemical reaction rendering them useless. In fact it is the slow reshaping of the plates, that does make much more sense.

Up until now I have very carefully monitored the voltages to make sure each battery is in the same condition and the greatest variation in voltage between them currently is 0.01 volts. Luckily there is no sign of deformation causing problems or fused plates yet.