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Lead Acid Woes - Sulfation, Inefficiency, etc.

Posted: Dec 02 2011 7:00am
by DrkAngel
SLA (Sealed Lead Acid batteries) deteriorate due to a process called Sulfation.
They are constructed with lead plates surrounded by electrolyte (Sulfuric Acid).
Sulfation is the sedimentation of sulfur, from the sulfuric acid, onto the lead plates, (lead sulfate).
This is a normal and constant process, all Lead Acid batteries succumb to it, eventually.
Keeping the battery at full charge delays this, most effectively.
Letting the battery sit, discharged, speeds up the process.
The deeper the discharge, the faster the process.

What does this do to a battery?

The sulfur, coating the lead plates, blocks efficient electron transfer.
This is why the battery shows full voltage, but voltage drops sharply when drain is applied, then voltage recovers when drain is removed.
Sulfur coating reduces the contact area of electrolyte to lead.
"Plate", accumulated electrons, discharge quickly, but can, only replenish slowly.

The other half of the sulfation process is that, without sulfur, sulfuric acid is, basically, water ... water is a very poor electrolyte, (electron storage media)!

So ... a double whammy!
Reduced rate and reduced capacity!

How else can you destroy your battery?

High rate of charge, or discharge.
Overvoltage charging, producing heat.
Either, will cause lead plates to heat and warp, possibly shorting, or evaporating electrolyte, allowing severe heat.
Some types of shorts will cause loss of a 2V cell, leaving a 10V battery, charge it as a 12V and worse damage will quickly occur.
Recommended charging rates are 8 hours, for full charge.
"Rated" Ah, on a SLA battery is, typically, when battery is discharged over a 20 hour period, some at 5 hr.
Discharging at a 1 hour rate will only output, about 60% of rated.

Oh! ... Using a standard "automobile" battery charger can easily destroy your SLA.
Voltage is, and amperage, can be, way too high, for SLA!

SLA are capable, but not ideal, for either rapid, or deep, discharges.
They are a mid 20th century technology, surviving as a cheap alternative to the "better", more expensive, alternatives.

Keys to prolonging life?

Charge, immediately after use!
Do not deeply discharge!
Charge at recommended rate, 8 hour.

What good are SLA, for eBikes?

Cheap, very affordable, intro to eBikes.
Helps you determine actual need-want, before making a big buck battery buy.
Might last years, but only with gentle use, and proper care ...

Re: Lead Acid Woes - Sulfation, etc.

Posted: Dec 02 2011 9:29am
by bigmoose
You might consider adding this page to the wiki! ... s_LeadAcid

In fact I would recommend to all members that when you author something that is archival, post it, but also add it to or start a ES wiki page on the subject for the future generations!

... which reminds me, I need to do one on the Wicked Infinitesimal Resistance Element called WIRE. :lol:

Re: Lead Acid Woes - Sulfation, etc.

Posted: Dec 02 2011 9:34am
by TylerDurden
Cursory information like the above might be best left to BU.

I suggest that wiki editing access be limited to guru status or above.

Re: Lead Acid Woes - Sulfation, etc.

Posted: Dec 02 2011 9:57am
by DrkAngel
Needed a concise, understandable explanation on SLA.
Took me years of effort and multiple battery replacements before I could get my mother to care for her mobility scooter (batteries).
She would run it till empty, then charge it, sometimes once a week.
Had to replace batteries twice a year.
Finally I gave up trying to explain it to her, wrote it down, printed it out, gave copies to her and her friends.
Guess it started a discussion at her Senior Housing Development, that she finally understood.
Her latest pair of batteries have lasted her for 3 years.

Strangely, she always insisted that her car's gas tank must be kept filled, even if it moved a bit below full, she must stop and refill it.

Sadly , my source of sulfated batteries has dried up.
I've had reasonably fair success at improving condition of these batts with a BatteryMinder charger w/de-sulfation function.

Re: Lead Acid Woes - Inefficiency

Posted: Oct 03 2015 9:44pm
by DrkAngel
Most SLA batteries are rated at a 20 hour discharge period.
Sadly, when in use at typical eBike discharge rates, 1/2 - 1 hour, actual battery output is a measly 50 - 60% of rated.

I finally found a graph that charts SLA inefficiency at various discharge rates.
(105Ah "20hr" SLA battery)
(.05C) - 20hr 105Ah @ 12.5V = 1312wh usable battery output
(.16C) - 5hr 86Ah @ 12.1V = 1040wh usable battery output
(.58C) - 1hr 60.9Ah @ 11.9V = 729wh usable battery output
(1C) - .5hr 52.5Ah @ 11.5V = 604wh usable battery output
(3C) - .1hr 31.5Ah @11V = 346wh usable battery output

Re: Lead Acid Woes - Sulfation, Inefficiency, etc.

Posted: Oct 03 2015 11:31pm
by Jon NCal
Also, best for longevity to fully charge and then kept on "float" charge in a temperature controlled environment. Is about 2.25vpc at 68 deg. F, but can vary with particular lead acid type and storage temp.

Re: Lead Acid Woes - Sulfation, Inefficiency, etc.

Posted: Oct 13 2015 11:48am
by 4LivesPerGallon
The OP failed to differentiate between the different kinds of Lead Acid batteries, which include: Wet cell, AGM and its sub-variants, gel, and ultra-high-performance Hawker Genesis.

Not to mention "discharge rates".

They all have different voltages and charging requirements.

Imo, the original posting is disinformation.

Re: Lead Acid Woes - Sulfation, Inefficiency, etc.

Posted: Oct 13 2015 1:42pm
by DrkAngel
4LivesPerGallon wrote:The OP failed to differentiate between the different kinds of Lead Acid batteries, which include: Wet cell, AGM and its sub-variants, gel, and ultra-high-performance Hawker Genesis.
I was only concerned about deep cycle SLA (AGM and Gel), as their being of, almost, reasonable consideration for eVehicle use..
4LivesPerGallon wrote:Not to mention "discharge rates".
Higher discharge rates are less efficient and more damaging. ... happy?
(Graphed .05C through 3C discharge curves! ... ?)
4LivesPerGallon wrote:They all have different voltages and charging requirements.
Wet cell can be safely charged at slightly higher voltage ... but may require periodic replenishment with distilled water.
(Not recommended for eVehicle use!)
4LivesPerGallon wrote:Imo, the original posting is disinformation.
Merriam-Webster wrote: DISINFORMATION: false information deliberately and often covertly spread
I don't believe neglecting to delve into the seemingly irrelevant or obscure segments of an increasingly obsolete technology should be called "disinformation"!

Re: Lead Acid Woes - Sulfation, Inefficiency, etc.

Posted: Oct 17 2015 2:04am
by 4LivesPerGallon
Much of what was stated by DrkAngel is, imo, erroneous.

Take for example, his statement that wet-cell batteries are allegedly "(Not recommended for eVehicle use!)".

Actually, if you go to, you'll see that most of the full-size (car, pickup trucks) EV conversions are powered by wet-cell 6V, 8V, or 12V wet calls, e.g. "Trojan" brand, and fitted with electrolyte recovery systems. (I have hands-on experience -- this is not "guesswork" or just reading about it.)

These Trojans, when charged properly, last 8 years, on average.

Also, the wet-cell marine "starter" batteries can last 20 years on a boat, because old fishermen know how to treat them -- not using the information from the manufacturers.

Although most lead acid batteries do not last many discharge cycles before deteriorating, a major study discovered that the "Dynasty" brand of lead acid batteries have nearly zero degredation after 1,000 charge cycles; proving that it is possible to have lead acid batteries that do not break down. That study, on wheelchair batteries, was on the Internet as of 2006-2008.

"Dynasty" was a battery brand by Johnson Controls.

I could go on.

The point is that most of the info on the 'net about batteries is false/incorrect, especially from the lead-acid battery makers.

The really knowledable people about scooter/ebike lead acid batteries are "Aerowatt", and Scott McGregor from, two electric scooter dealers, circa 2001-2006.


Also, the actual charge curves of the Soneil battery chargers, which was, in 1999-2005, considered the best of 24V-48V battery chargers, differed from their published information. These relatively-expensive Soneil chargers saved a lot of electric bike/scooter battery packs from early death.

From the intermittent "berserk" behaviour of Zivan EV battery charger, I am guessing that the Zivan battery charger is designed to secretly destroy battery packs.


Most of the postings on this board are about "Lithium battery problems", or "BMS problems", or "balancing problems", or "LiPO fires", or battery-pack welding.

We didn't have those issues, or concerns, with lead acid battery packs.

Lead acid batteries worked very well. Most of China's e*cycles run on them. However, in North America, incompetent and/or dishonest dealers/manufacturers destroyed the market, with some exceptions.

Lead acid batteries cannot be fast charged, except for the Hawker Genesis, which must be charged at 1C minimum. A 48V scooter on Hawkers was fully charged in 20-25 minutes. These Hawkers had a life of 200-600 cycles. However, if charged at less than 1C, they died in ~10 charge cycles. Getting the correct charger for a Hawker requires doing your homework.

The Peukert effect isn't a problem if you bought Panasonic AGM's. Buy only "high discharge rate" batteries.

If you're going SLA in your ebike on a budget, I strongly suggest: Buy Panasonic AGM.

Never buy gel cells. Never buy Sonnenschein -- they used to be excellent, but this company changed their quality to "bad" imo.

Re: Lead Acid Woes - Sulfation, Inefficiency, etc.

Posted: Oct 17 2015 2:21am
by 4LivesPerGallon
Imo, the title of this post is misleading because it lacks key information about the subject matter.

DrkAngel also fails to mention "supercharged" lead acid batteries, aka "battery doping" which was well-known in California, 1999-2005. Circa 2005 some trouble-makers/hackers, destroyed, or took over, the online electric scooter/ebike clubs. Disinformation became rampant after that.

Doped lead acid batteries had incredible dischrage rates, making it possible for a 20MPH scooter to go 60MPH.

The "leading inventor" was DeafScooter, a guy who moved to Taiwan from California.

Look at the speed of Deafscooter's lead-acid scooters -- 65MPH with battery-doped Hawkers. With GPS proof.

Too bad Deafscooter didn't get any recognition in the US. He was only one of a few people who knew about battery doping, but he didn't share it publicly.

Re: Lead Acid Woes - Sulfation, Inefficiency, etc.

Posted: Oct 17 2015 7:37am
by DrkAngel
4LivesPerGallon wishes to add to the list of "Lead Acid Woes":

#1 Lead Acid battery manufacturers indulge in a form of disinformation that prematurely destroys their batteries! .. but old fishermen have formed some secret society to combat-circumvent this dastardly conspiracy?

#2 Certain manufacturer(s) battery charger(s) is(are) secretly designed to destroy battery packs!

#3 Lead-acid battery makers are in some conspiracy to publish false/incorrect info on the net?

#4 Trouble-makers/hackers, have destroyed, or taken over, the online electric scooter/ebike clubs. They indulge in some rampant disinformation about Lead Acid batteries.

4LivesPerGallon ... ?
Do you have any explanation as to why, you believe, there seems to be a nearly universal conspiracy, manufacturers and users-posters alike, to degrade and destroy Lead Acid batteries with overwhelming disinformation and actual sabotage.

Re: Lead Acid Woes - Sulfation, Inefficiency, etc.

Posted: Oct 17 2015 1:28pm
by 999zip999
Let's hear about desulation and a magic homemade box to restore life to a dead lead.

Re: Lead Acid Woes - Sulfation, Inefficiency, etc.

Posted: Oct 25 2015 2:09am
by amberwolf
4LivesPerGallon wrote:Doped lead acid batteries had incredible dischrage rates, making it possible for a 20MPH scooter to go 60MPH.
The only way that could happen is if the scooter was limited by the current output of the batteries, causing them to sag when the small (relative to the speeds) currents would be pulled from them when going above the lower speed.

The scooters would have already had to be fully capable of the higher speed, with that current/sag being the *only* limiting factor.

The catch is, as far as I have seen, the limiting factor is usually voltage (to be capable of reaching the higher speed unloaded/offground) and the total sustained wattage capability of the system (to be capable of reaching the higher speed when loaded (real riding under road conditions), and maintaining that speed without damaging the motors, controllers, wiring, etc).

As for Deafscooter, before my time here even started, he destroyed his *own* work here on ES in many posts. No one did it to him or his stuff; he deleted his own content in some cases, in others he refused to even post anything more than cryptic stuff that might as well be nonsense, callng it "top secret"--why bother posting anything at all if it's top secret? :roll: From what I've read, at least some found it hard to take him seriously because of that; others appreciated his skills, but found his secrecy/deletion of data problematic, which I can understand especially here on ES where being open about what you post is what it's all about, so others can learn from it.

I understand he had some dispute with someone else near the end of his time here, and deleted things because of that, too, but AFAICT he was deleting his own content long before that. ... mit=Search

Re: Lead Acid Woes - Sulfation, Inefficiency, etc.

Posted: Jun 01 2016 4:48am
by DrkAngel
Why would you inflict someone you care about with your sketchy weird, complex, octopoid, Snagglepuss Slabatt rig?
Lead acid batteries are heavy, inefficient, short range, short life, require knowledgeable care and in eBike use ... are very expensive!

Schwinn with the 48V 30A controller:
At full throttle will draw 30A from 10Ah batteries ... until near top speed = ~25mph, which:
Outputs less than 20% the usable range of 10Ah LiPo
Outputs less than 10% the usable range of 10Ah LiPo when discharged to only, the recommended, 50%.

Re: Lead Acid Woes - Sulfation, Inefficiency, etc.

Posted: Jun 13 2016 12:11am
by bigmoose
I have a couple of UPS's around the house/lab (APCs rated from 1100 to 2000w) that run two 12 volt sealed lead acid batteries of 12 AHr and 18 AHr.

I would be interested in the combined wisdom of what would be the optimum float voltage for these batteries. I typically get 4 years out of a set. They are running at 13.8 V float at room temperature. I was thinking of bringing that voltage down 0.10 to 0.15V total.

I think the failure mode is dryout.

Re: Lead Acid Woes - Sulfation, Inefficiency, etc.

Posted: Jun 13 2016 1:02am
by amberwolf
I'd expect the best float V to be whatever the label on the SLA is...but I havent' experimented with that.

What I would myself do is create a relay/contactor circuit to connect / disconnect the SLA from the charger circuit once it reached full charge, and then reconnect it once it self-discharges below some point, so it just tops it off but isnt' always running a current thru it.

I've read that people have re-filled SLAs with water, injecting it in thru the vent holes tiny amounts at a time to let it absorb back into the gel. But I don't know how well that works or how long it takes, or how often it has to be done to prevent degradation.

Keep in mind that I'm not an SLA guru, though...have only played with them some back before I got some NiMH and then LiFePO4, NMC, RC LiPo, etc. I honestly haven't done anything with my SLA since moving back into the house after the rebuild other than use them to test a trailer for load capability (along with a bunch of bricks). :lol:

Re: Lead Acid Woes - Sulfation, Inefficiency, etc.

Posted: Jun 18 2016 7:44pm
by bigmoose
Finally got time to pull the sealed top strips off the "failed" 12V 12AHr Valve Regulated glass mat battery. All cells were still under vacuum and each cell took 12 cc of distilled water easily.

Will let it soak for a few days, then recharge and see what capacity we have.

This has me thinking that I should open up all my VRGM batteries in my UPS's every 2 years and add 6 or 7 cc of distilled water to each cell.

Re: Lead Acid Woes - Sulfation, Inefficiency, etc.

Posted: Jun 19 2016 4:49am
by DrkAngel
AGM (Absorption Glass Mat) might reintegrate water, it functions similar to a sponge ...
but Gel batteries should prove resistant to integration, extreme reabsorption time, if at all?

VRLA (Valve Regulated Lead Acid) function negated by removing "top strips" (or puncturing) and is seemingly important to re-seal for any possibility of reasonable prolonged life. ... ?
Valve function keeps battery pressurized at safe pressure during charge, to minimize water loss.

Adding too much water will weaken the strength of the electrolyte.
The only possible way to accurately replenish water might be by comparison of precise weight measure (from when new)?

Important to use distilled water only!

Re: Lead Acid Woes - Sulfation, Inefficiency, etc.

Posted: Jun 19 2016 5:05pm
by DrkAngel
DrkAngel wrote: Important to use distilled water only!
... however, there is purported success of rejuvenating some batteries by refilling with Epsom salts dissolved in distilled water.
I would suspect that this strengthens the electrolyte which weakens due to the loss of sulfur through sulfation?

There are several youtube proponents who demonstrate ... but use FLA (Flooded Lead Acid) batteries.

Re: Lead Acid Woes - Sulfation, Inefficiency, etc.

Posted: Jun 19 2016 8:39pm
by bigmoose
The UPS this is out of uses two 12V 12 AHr batteries in series... One had high internal resistance, and the "good" one seemed OK with respect to Rinternal.

So today I popped the caps on the "good" (though 4 years in service) Valve Regulated Glass Mat and decided to add some distilled water to it.

Surprisingly, 4 cells took the 12 cc with no problem, but 2 cells were "full up" on electrolyte. To me this was very interesting, that the cell inconsistency could be of this grand magnitude!

I sure wish there were more details out there on Valve Regulated Glass Mat batteries and how to extend their life.

Re: Lead Acid Woes - Sulfation, Inefficiency, etc.

Posted: Jun 20 2016 1:48am
by DrkAngel
Lead Acid batteries run a voltage tightrope.
Higher voltage induces grid corrosion and electrolyte evaporation.
Lower voltage allows sulfation.

1. Edited to clarify - A "solution" would be using the higher range of charge and float voltages in conjunction with active cooling (a fan?) for the batteries. Outgassing does not occur till much higher charge or float voltages if batteries are kept at lower temperature. Especially the older, UPSs seem to idle at a warm 35ยบC++. Lowering battery temperature allows the higher voltages without outgassing

On SLA batteries, the VRLA pressure seal restricts outgassing till somewhat higher voltages. But no seal is perfect forever and some percentage and degree of failure will happen eventually.

2. Another "solution" would be using the lower range of charge and float voltages in conjunction with the frequency pulses or modulations of a desulfator ?