I was linked to http://www.rainingspiritdojo.com.au/downloads/alternativeleadacidsulphates-overview-dominichawkins-v1.4.pdf at some point recently.
It's essentially saying, "You can get more useful life out of heavily sulfated batteries by changing electrolytes." You get less capacity out of the batteries than on regular battery acid, but you can deep cycle them without any problems.
And, apparently, it works well enough assuming the problem is sulfation, not lead loss or plate corrosion.
Is this... a thing that works? Has anyone played with it? There's a stack of old, dead car batteries I have access to if I want to play...
I really doubt it, the sulfate crystals block the surface of the plate, so the battery capacity is now diminished. Plus if the batteries have been sitting idle for 3 months after they were pulled as dead......
I don't think it's worth the bother, but if you have a free source of acid.....
The mechanism, as I understand it, is to actually dissolve those crystals off and back into the (new) solution.
I was going to at least try it out on some of the freebie batteries I can get - find one that still sloshes and go at it. They're properly ancient, though, and I expect most of them have frozen at some point or another.
If the crystals would dissolve, they would dissolve back into the original electrolyte. When they get hardned, it's much more difficult to dissolve them. I suppose if you got some from a lab, fresh, you could swap fluid and make progress.
My understanding is you should add nothing but water to a FLA battery. The Lead Sulphate is the acid and lead combined, if you empty a battery in this condition and add fresh electrolyte you end up with the wrong mixture.
My battery bank is all refurbished golf cart batteries which I have desulphated using.
http://leadacidbatterydesulfation.yuku.com/topic/1162/Direct-Drive-Desulfator-Design?page=1#.V07B5pF95hE
What it does is hit the battery with very short bursts >10 nano second @2-3 KHZ from a bank of low ESR capacitors which are at about double the nominal battery voltage.
This device breaks up the Lead Sulphate, which becomes Lead and Sulphuric acid again. For example my wife's car battery would not start the car 1 year ago as we where coming into winter, after 48 hours on the desulphator it has been fine the last 12 months.
Right, this is basically making a new battery chemistry using the lead plates. I don't have enough of a chemistry background to really understand the details.
We have all at some time had a dream of refurbishing batteries.
The biggest problem is the mechanical damage to the plate structure by the sulphate crystal growth.
Plates become distorted and broken causing dead shorts and massive jumps in internal resistance.
Desulphators may work on lighter growths but can not repair structural damage!
The longer a battery has been sitting the greater the damage.
If someone has taken the time to remove all the acid from the cells and wash the battery out well then the damage may be less.
I have pulled apart a lot of auto batteries and other styles and the damage from the sulphation growth is shocking.
The other problem is that most modern batteries are made of crap products!
The lead is highly contaminated with other metal for reasons known by the manufacturers and these materials do not resist decomposition
by the acid bath they live in. The positive plates are the worst effected and decompose in a relatively short time even when in use.
What is the point in making a tank of a car battery which will last 15 years? Equals low profit and no return customers!
The other problem is stratification where the acid separates from the water and forms a high h2 so4 concentration at the bottom of the battery. This acid eats at the plates when the battery is unused and causes more plate damage to both the positive and negative plates!
When you pull a battery apart that has suffered from stratification it looks like rats have chewed at the bottom of the plates. :o
Not a lot of good news.
In a nut shell, if the batteries are freshly removed from their place of use, go for it!
If they have been sitting there for months and years, well it is pretty much a waste of your time and power to run the desulphators!
Just my opinion from a few years of working with batteries. :D
Plus - if you do drain them then what do you do with all that lead contaminated electrolyte ?
Modern lead acid battery recycling reclaims and recycles all the components and doesn't pollute the environment.
Larry
Save your electrolite as in this country the thought police do not allow battery retailers to sell sulphuric acid anymore! They have to account and keep a log for every liter, believe or not.
Filter it and store it in a suitable poly drum.
There is sure to be a cleaning process and acid lasts a long time.
Would periodic steering up acid inside each cell be beneficial to battery life? Does anyone know?
Quote from: sigp2101 on June 23, 2016, 01:15:47 PM
Would periodic steering up acid inside each cell be beneficial to battery life? Does anyone know?
If you mean "stirring" then I would point out that a good equalizing charge and the resulting bubbling of the electrolyte accomplishes that. So, yes!
Quote from: TomW on June 23, 2016, 03:10:53 PM
Quote from: sigp2101 on June 23, 2016, 01:15:47 PM
Would periodic steering up acid inside each cell be beneficial to battery life? Does anyone know?
If you mean "stirring" then I would point out that a good equalizing charge and the resulting bubbling of the electrolyte accomplishes that. So, yes!
Yes that is what I meant, stupid auto correct work both ways.
So what if we periodically when checking up electrolyte levels, lets say, slide in tiny little hose to the bottom of the cell and pump air bubbles to stirrup electrolyte. Simple fish tank air pump could be used for this. This should prevent/prolong stratification. Agree/disagree? I mean car batteries are in constant motion, charging discharging every day and they last on average 5 years. So occasional shake up should be good for longevity of our deep cycle stationary batteries.
sigp2102 & TomW,
I have mentioned the use of a turkey baster that I use for the same reason. I use a large plastic one and pump the acid up and down to stir up the acid mix. russ_drinkwater is exactly right when he says long dead batteries are too sulfated to recover. I have opened many lead acid batteries and found the same thing he has. I did a winter in a battery shop in Alaska where we built and rebuilt batteries. I have seen that eaten away bottom of plates......that's sitting too long and almost always not recoverable.
My recovered Rolls-Surette set didn't sit long....system went dead and sat for a month before they decided to scrap it. Shame! A blown FET in the Trace C-40 charge controller took out their whole system. They were in $30K and I bought the remains for $800. No one here is even remotely qualified on off grid systems and advertising so except myself..........so I'm in the game here locally......Santa Cruz and Santa Lucia Mountains......Santa Cruz , Monterey, and San Benito Counties California
David
A good equalize once a month is enough. But if you have a massive amp bank say, 2000-4000 amps and a low output solar array of
500 watts I would be of the mindset to equalize twice a month to ensure reduced stratification and sulfation.
Moving your cells around to agitate the electrolyte I would not recommend as car batteries are made up of numerous light grid plates both on positive and negative sides. Your better quality deep cycle solar batteries have similar negative plates of light grid construction.
However the positive plates which are subjected to massive amounts of abuse are more often than not "plante" plates as in the trojan batteries or cylindrical rods in pockets as in raylites. And these plates are extremely heavy and can be up to 10mm thick and as such any mass that is vigorously moved around will be subjected to a lot of stress (in acceleration and deceleration). It may seem trivial, but these batteries are not really designed to be used in tractors trucks and the like. Slamming and bumping in my opinion would be destructive to your deep cycle solar batteries. The turkey baster to draw up and inject acid/water in the cells would definately mix the 2 fluids.
Any thing I have said which someone feels is incorrect I stand corrected if you know better :o ;) ;D
That's the reason for Minimum Charge Rate. Even the daily absorb is useful for de-stratifaction.