Trying out battery desulfator

[Rick Law]

Back in December of last year, I started a thread about using epsom salt to revive SLAs. 
https://www.eevblog.com/forum/chat/epson-salt-in-lead-acid-battery/

The conversation drifted to using pulse-device for SLA revival a bit.  Cheap desulfators are readily available but web research shows desulfation requires much better equipment.  Given how cheap those cheapies are, I was going to try anyway...  and I did.

Folks here may find the results interesting - measurable improvement but no meaningful improvement.

Here are the details for those interested.

I have 3 kind-of-dead SLAs and I tested it with the best of the three and it is originally rated at 22AH.  This battery was not maintained for a few years, it would "fully recharge" in sub-seconds and went back to dead on any load.  After trickle-charging, it was holding 12.6V and was able to deliver a few minutes of charge before January 7.

For testing, I use a 20 Watt 12V car light bulb as load.  Each run, I merely timed how long it takes for it to drop from full charge 13.6V to 10.5V. It will start at about 1.7A when battery is full, down to about 1.5A at 10.5V.  10.5V is low, but according to their spec, this is what they discharge to for the 22AH number.

Except where noted, the in-between days/hours were times when the desulfator was connected - So, approx 24hrs of desulfator run between discharge runs, except the last which was 2 months of pulsing from 1/28/20 to 4/3/21.

As expected, but not as hoped; it did something, measurable but not meaningful.


Run time is measured by an INA219 with an Arduino NANO
210107 - 6m58 (before any pulsing)
210108 - 7m44
210109 - 25m57
210110 - 23m13
210112 - 29m51
210112 - 21m43 (Before interruption)
210117 - 16m41 (Resumed from interruption)
210118 - 13m50
210118 - 11m46
210119 - 10m16
210119 - 0m03 (Interruption)
210121 - 13m47
210121 - 11m41
210124 - 14m35
210128 - 11m23
210128 - 10m33
210403 - 24m09

Yeah, it improved from 7 minutes to 24 minutes of 1.5A.  For a 22AH SLA, 24 minutes of 1.5A is still a dead battery.  Measurable improvement but not a meaningful improvement.  I do notice that at lower amp discharge, it improved more - but I did not collect data on that so I don't know for sure by how much.

Oh, a few words about the pulser.  The sticker said it pulses at 10KHz, it actually pulses at whenever it can, probably when the capacitor is charged enough or something like that.  As measured by my Hantek 6022BE USB Scope, I can clearly see an "attempted pulse" (very low amplitude pulse) at 64KHz.  Every 4 pulses or so (that makes it around 20KHz), it builds up to a larger pulse at about 0.5V.  At longer intervals, it has much larger pulse at over 1.25V.  There are times that it couldn't do the larger pulse.  The pulse amplitude varies depending on the state-of-charge of the battery.  The scope output is attached.

I know the "Battery Desulfator" isn't going to do much, but I was hoping for a bit more.  I do not regret "wasting" $15 for this thing.  It was fun experimenting with it.

Edit - correction made, the battery was not maintained for longer than 12 month that I initial wrote, that was a different battery.  This one was a few years...

[james_s]

You might have gained just as much simply by charging with a normal charger and discharging with the lamp several times.

The desufator may work better on a conventional lead acid battery. The SLA type I have never had any luck trying to revive once they go bad. I've gotten significant improvement by adding distilled water to the cells but not enough to to really be worthwhile. When I've looked inside old SLA batteries they were always completely trashed, the plates crumbling to dust.

[T3sl4co1l]

A gel cell I ruined last year, I tried pulsing much more aggressively than that (what is 0.5V supposed to do anyway? what a quack device).  I didn't notice any significant change in V(I) curve, under high voltages (>18V), or after some time (thousands of pulses).

Tim

[Rick Law]

You might have gained just as much simply by charging with a normal charger and discharging with the lamp several times.

The desufator may work better on a conventional lead acid battery. The SLA type I have never had any luck trying to revive once they go bad. I've gotten significant improvement by adding distilled water to the cells but not enough to to really be worthwhile. When I've looked inside old SLA batteries they were always completely trashed, the plates crumbling to dust.

It was an "SLA" but still just a flood-acid battery.  The openings are glued with rubber caps over it.  Late last year, I tried refilling the low-level cells with distilled water.  Gaining nothing, I emptied them and refilled with car battery acid which should be 50% H₂SO₄.  That didn't gain much either.  Desulfator was the last bullet in the chamber.

A gel cell I ruined last year, I tried pulsing much more aggressively than that (what is 0.5V supposed to do anyway? what a quack device).  I didn't notice any significant change in V(I) curve, under high voltages (>18V), or after some time (thousands of pulses).

Tim

Yeah...  I was not expecting much from these cheap toys.  Web research (from a graduate conference paper) shows they got 95% recovery at 1MHz pulsing, but not sure what amplitude was it that they used.

I can't say this cheap toy doesn't work.  It is measurable improvement, just not meaningful.

[tautech]

Played with desulpfators years back and they weren't much good until you optimized them.
7A @ 60V @ 1 KHz into SLA's and LA's was the best I achieved using custom flybacks and MOSFET ON times nearly to magnetics saturation. First use in anger of good current probes for both monitoring currents into magnetics and scoping the magnitude of the current produced.

Powered only from the battery being pulsed it was normal to get a battery voltage improvement overnight despite the pulser was being powered by the battery all the time.

[Gyro]

It was an "SLA" but still just a flood-acid battery.  The openings are glued with rubber caps over it.  Late last year, I tried refilling the low-level cells with distilled water.  Gaining nothing, I emptied them and refilled with car battery acid which should be 50% H₂SO₄.  That didn't gain much either.  Desulfator was the last bullet in the chamber.

You need a new plate set. 

https://www.eevblog.com/forum/chat/rebuilding-lead-acid-batteries-the-street-vendor-method/

[Rick Law]

It was an "SLA" but still just a flood-acid battery.  The openings are glued with rubber caps over it.  Late last year, I tried refilling the low-level cells with distilled water.  Gaining nothing, I emptied them and refilled with car battery acid which should be 50% H₂SO₄.  That didn't gain much either.  Desulfator was the last bullet in the chamber.

You need a new plate set. 

https://www.eevblog.com/forum/chat/rebuilding-lead-acid-batteries-the-street-vendor-method/

I saw that video - it was brought up by floobydust in that epsom salt rivival thread (reply #38) last December.  I am impressed by how the guy re-manufactured the battery.

Actually, I wish the battery has individually and standardized replaceable plates (back to just plain flooded acid?) for each cell.  With that, almost anyone could DIY and recycle the battery back to working condition.   This wont be for saving money as shipping and handling cost for a lead-plate set would cancel or exceed savings -- but it would almost certainly promote recycling.

Truth be told, I was engaging in this "see what I can do with these batteries" project more so to get back into doing more EE & Arduino instead of getting a working battery back.   I have hardly touched my soldering iron in the last few years, and my Arduino-programming PC was long since dead.  Getting my INA219+Arduino working again, finding all my cables (where did I put my scope probe...), re-loading my tool chain on a different PC (old one dead), so on...  Swapping plates wont accomplish the goal of snuggling up with actually doing EE again. 

Back to desulfation...

I understand that it may take a few cycles of charge/discharge for gain to be shown.  With my Arduino+INA219+replacement_PC working again, I can now program and log.  Once I found my relay modules, I will let it self-run switching from charge<->discharge.  Mean-time, I am cycling that manually now.  If recovery comes anywhere close to 30% original capacity, I'd be real happy.

[bsfeechannel]

The best desulfator I know is the lead acid battery manufacturer. I had two dead batteries and I did a little research about desulfation, but I reached the conclusion that there's no effective way of doing that.  You need to rebuild the whole thing. So I bought I new one and even got a 30% discount for trading in the old one to them.

[james_s]

You still could remanufacture it yourself at home if you really wanted to, I mean none of the tools or facilities in that video were exactly high tech, and with just a little bit of care it could be done a whole lot more safely. In the end though is it really worth it? If I could not even earn minimum wage with my time and really, really needed a battery, or if it was vintage or some weird size that I could not easily get I might give it a try, and it would be an interesting challenge. In general though it's a lot easier to just turn it in for scrap and buy a new battery. Scrap prices on old batteries had really gone up the last time I dropped some off.

[SilverSolder]

The best desulfator I know is the lead acid battery manufacturer. I had two dead batteries and I did a little research about desulfation, but I reached the conclusion that there's no effective way of doing that.  You need to rebuild the whole thing. So I bought I new one and even got a 30% discount for trading in the old one to them.

If a battery won't take a charge properly, replacement is the only thing that makes sense.  I do think car batteries are getting expensive at $100 - $200 a pop,  but I guess as long as the printing presses keep running, we'll be OK...   

[nctnico]

The best desulfator I know is the lead acid battery manufacturer. I had two dead batteries and I did a little research about desulfation, but I reached the conclusion that there's no effective way of doing that.  You need to rebuild the whole thing. So I bought I new one and even got a 30% discount for trading in the old one to them.

A lot depends on how good the charger is and whether a battery is treated well or not. One of my customers is doing lead-acid battery regeneration on an industrial scale (batteries from equipment like electric fork lifts, etc). They told me that in many cases they can revive a battery (not only using pulsing but also through flushing the battery using proprietary chemicals; pulsing alone isn't going to do the job) but if the end user has a good charger and doesn't abuse the batteries there is not much to revive. At some point a battery is simply worn out.

[Rick Law]

...
...
At some point a battery is simply worn out.

Funny thing about perception.  When I took those worn out batteries from the enclosure of the UPS, those guys look the same as the day I put them into the enclosure.

I know they have been cycling in the UPS for years, yet they look so clean and new it is hard to think of them as old worn out stuff...  But yet they are...

[james_s]

Funny thing about perception.  When I took those worn out batteries from the enclosure of the UPS, those guys look the same as the day I put them into the enclosure.

I know they have been cycling in the UPS for years, yet they look so clean and new it is hard to think of them as old worn out stuff...  But yet they are...

Generally speaking, batteries don't really wear much on the outside unless they are in REALLY bad shape.

[SilverSolder]

Funny thing about perception.  When I took those worn out batteries from the enclosure of the UPS, those guys look the same as the day I put them into the enclosure.

I know they have been cycling in the UPS for years, yet they look so clean and new it is hard to think of them as old worn out stuff...  But yet they are...

Generally speaking, batteries don't really wear much on the outside unless they are in REALLY bad shape.

...unless they are leaky Duracells! 

[james_s]

...unless they are leaky Duracells! 

IMHO those are in really bad shape right out of the factory.