Do desulfating battery chargers actually help with the battery state of health? (2 Viewers)

[e9999]

I have read many discussions about this with a range of comments from snake oil to works great. Fairly inconclusive overall from what I can tell.
I have one, a Battery Minder Plus 12117, a little inexpensive guy, it has the desulfating feature, basically a high-frequency pulse added on the "DC" according to the manufacturer. It tops the batteries off at 14.4V at about 1A IIRC then goes on Float around 13.5V with something like 50mA (from memory).
I have used it for years to top off every so often my batteries in storage. Does that just fine.
I have one old battery in fairly bad shape. A Sears Diehard Gold FLA 100Ah (I think, given the size - not on label). 2016. It was used in a truck for about 5 or 6 years. Then removed when becoming questionable and put in storage for a couple of years (with regular refills). There was no obvious bad cell, voltage was still in the 12V range. Just old.
I decided to leave the desulfating charger on it full time for a while to see what will happen.
I tested it before doing that. Got 637Wh from full at C/50. Very poor showing if 100Ah.
Left it on the desulfator for something like 4 or 5 months.
Tested it again. Same conditions. Now got 908Wh from full.
So, somehow, it got a 42% increase in capacity. Not bad. But not exactly like new, either, if 100Ah nominal.
Hardly a good scientific test, evidently. And, of course, no way to tell what caused that increase, exactly.
YMMV.

 

[TreadingLight]

I have a Schumacher smart charger that ran up well over 15v on an old battery that I wanted to get more life out of.

Alarmed I called the manufacturer and they told me it was using high voltage to desulfafe the battery in response to high internal resistance.

I guess you can reduce sulfation with higher voltage but at the risk of damaging the battery.

I don't trust that charger anymore.

I plan to get a newer noco charger going forward.

Anyhow, just a cautionary tale.

 

[jht3]

i want to say they do, but i don't have any long term personal experience

i do have long term experience with the Battery Tender 1.25A charger. I keep a car on it 100% of the time which rarely gets driven (200 miles in 3 years....sad...but that's a different subject). I recently had to replace the 5-6 year old wet cell battery it was maintaining, after it could no longer start the car.

I have a Noco Genius 10A charger w/ "repair" mode, and that didn't help restore that failed battery. I guess it was just too far gone. Had I used the Noco on it 100% of the time, maybe the battery would have lasted longer. I think it will desulphate the battery as part of its normal maintence profile.

Others I know have similar experiences with the Battery Tenders. I think they are just using old charging profiles which don't auto desulphate the battery every so often.

The Noco I have primarily for the AGM in my 80 series, when I let it sit a long time or when I just want to fully charge it beyond what the 80 series alternator can do. It also has a 12v "supply" mode which I use enough. The old Battery Tender doesn't support AGM or 12v supply. I should probably replace it with a smaller Noco.

 

[e9999]

^^ my charger does not exceed 14.4V RMS including the pulses. I vaguely remember putting it on a scope and seeing very short moderate voltage pulses that would not affect significantly the average voltage. The principle they are using / referring to has to do with the frequency more than the voltage I think.

But as to your 15V, that does sound ominous to old folks like me, but if the internal resistance is so high that the current is minimal, that may not be a problem in reality. I suspect that the usual concerned reaction to charging over 14.5V had much to do with the old dumb chargers that would boil the water when not stopping rather than because of the electrochemistry of it all.

 

[peesalot]

e9999, my exp after doing same for small gen batts is it will restore somewhat but that reverses & they go back to dead after 1 or 2 starts. I find it works better the newer the batt, sitting dead seems to just wreck them. Now that said, how come I can leave AA batts in various crap and they are live years later, some die in minutes, go figure. Question, are there better, bigger, quicker battery restore process or is the desulfate thing the deal ?

 

[baltistyle]

Generally desulphation is a short process and is not happening the entire time the battery is on the charger. All the chargers (charger not tender) I have require me to choose the cycle, which is limited and not automatic. I’ve not looked a tender with auto desulphation. It does help to clean the catalysts in the battery. Remember that charges don’t work when a battery gets to low and you may have to run the deal battery in series with a good battery until the voltage raises enough for the charger to work.

Yes desulphation works but it must be used before death for best results and will not get you back to new, but extend the life. Run a couple cycles and make sure your battery is filled if you can.

 

[e9999]

My charger is low power and intended more as a long-term maintainer than for quick charges. The instructions do say that it may take 2-4 weeks for results to show with badly sulfated batteries. So, definitely not a short process -for this charger at least- if it works at all. It does seem reasonable that a high frequency process may take some time to make a difference. As stated, I left it on for several months.

All this in contrast to the notion that you can rescue a battery by zapping it with high voltage and high current, which I also don't see a consensus about, but seems iffier to me.

Apparently, it's all about getting rid of the big crystals on the plates.

 

[baltistyle]

Gotcha, I’ve never used a tender with desulphation, only chargers. It does work.

 

[Mrtwooooo]

I keep my two odyssey batteries connected to a Battery Minder 12248 charger if it sitting more than a day. So far i've been going on 7 years from my group 31 battery. I have been pretty pleased with the charger so far. I also keep my MR2 connected to a smaller Battery Minder charger. Its been holding the battery for several years now. Cranks the car every time.

I also have two Noco chargers. A 5 amp and a 10 amp. I like how you plug them in and they go to the last setting used. Unlike the battery Minder where you have to set it everytime. The one big drawback i've seen with the Noco chargers is it doesn't hold the battery at a constant float voltage like the Battery Minder does. It seems like when the Noco gets to its last stage of it's charge cycle it mostly just watches the voltage and turns back on at some lower voltage thats well below its float voltage (Odyssey batteries say ~13.5v). I've left a battery connected to a Noco charger overnight and I come back the next day and find that the voltage was only about 12.8v and in its maintenance mode.

When I'm traveling I will take the Noco chargers because they are small, easy to use and can do up to 10 amps. But for storage at home I am using the Battery Minders.

My one concern is if being at a Float voltage of 13.5 for say a month at a time does any kind of harm to an AGM battery. Seems like some FLA batteries may slowly loose water in the battery from evaporation. I'm somewhat doubting its bothering an Odyssey AGM. I have a Victron Smart Shunt on the Group 31 battery and when the Battery Minder is in Float mode its barely putting about 1W of power into the battery to maintain it at 13.5v.

I think if I were to buy another charger (I currently have 4) that I would look at the Victron Blue Smart Charger. You can go in and basically set specific Absorption, Float and Storage voltages for your specific battery requirements. Just don't think it does any kind of desulfating.

 

[ntsqd]

I recall seeing this company when they first were started. Their only product then was solar powered maintainers with a desulfating step in the cycle. I've long thought that was a good idea.

PulseTech

PulseTech

pulsetech.com

Our camper is set-up such that the multi-stage solar charge controller eventually gets connected to the starting batteries too.

 

[e9999]

Setback...

I did test that battery again by using a light bulbs load and brought it down to about 6V. Yes, I know that is not recommended but I wanted to know the "full" capacity and figured that if that test wrecks it, it's pretty much going to be useless for actual use anyway.

Well, I don't know if it's that low voltage that did it, but it looks like I lost a cell during or after the test.

So, very likely, it did look temporarily better after the desulfation but was actually still in bad shape and conked out quickly. Something like what was mentioned above by P. Must have been some crystals dying to bridge the cell and just waiting for a good opportunity to misbehave.

So, yea...

 

[e9999]

update: the dang thing is down to about 400Wh at low current. It's done for! So, not a resounding success for the desulfating approach, unfortunately. I had some hopes there for a while...

 

[e9999]

Shoot, basically I wasted a good deal of time working on this. It seems confirmed (yet again) that once a FLA battery is a few years old, forget it. Not worth fighting it. Yes, you can make it last longer with regular maintenance and all if you start early, but the FLA technology can only handle so many cycles and years, and it's likely wishful thinking to hope for much more. That one is 8 years old after all. But, of course, all of you knew all this already and probably wondered why I bothered. Me too... But at least it was interesting to look into this. I will definitely keep using the "desulfating" maintener for batteries in storage, though.

If it weren't for the low price and high amps, I'd have jettisoned all FLAs a long time ago... sheesh... that's what, 150 y.o. tech now?

 

[ntsqd]

Just because it's old doesn't mean it's useless. Look at the attendant "costs" that come with later battery chemistries. Some of them are not too pleasant if things go sideways, others aren't too pleasant during the creation of those batteries.

I have an Odyssey battery that's dying after ~3 years. It's not had a great life, but I haven't deliberately abused it either. I believe it's downfall is due to the regulator of the vehicle that it is in. I only recently discovered that while Odyssey says 14.7 VDC the regulator stops at 14.4 VDC, so it has been chronically undercharged.

 

[e9999]

I'm not convinced that a couple of tenths of volt at the top makes a big difference in real life TBH, but I also don't know that for sure, and yes my AGM says to charge at 14.6V, so I guess it's best to follow what they say. But then again, FLA manufacturers do only claim comparatively short number of cycles and life expectancy, so it's not like we can expect 10 years out of those things. Whereas I do hope to get that out of my LFP ones.

On a related note, I've always meant to look into the Equalization issue during FLA charging, but never really got to it. Maybe that also makes a difference? Victron has provisions for that in some of their chargers.

 

[ntsqd]

Marine and off-grid applications (solar, wind, etc.) seem to have some pretty sophisticated charging methods & systems that are all pointed at the various forms of Lead-Acid batteries.