Increasing lead acid battery life

[dnix71]

My string of flooded hybrid marine batteries is aging and I was looking around for a life extender. From my college days I think I remember why PbSO4 batteries age.

Lead sulfate/oxide is almost insoluble in water. Lead acetate/nitrate however, is quite soluble. It's the anion that matters. As you discharge the battery, the sulfate concentration goes down, allowing lead to move into solution. The lead in solution interferes with recharging. The lead must leave before the sulfate plates can be turned back into oxide plates.

Any lead sulfate that precipitates and settles lowers the SG of the acid, and the capacity of the battery as well. Lead sulfate build-up on the oxide plates also decreases battery capacity and life.

Ideally, something that would scavenge the lead from solution and return it to the proper plate would increase the battery life, liike halogens are used to scavenge tungsten in light bulbs.

Nitric acid won't work since it would oxidize the lead and release NO2. Tetra sodium EDTA is available cheap from eBay. It scanvenges lead (and other heavy metals) well, but I'm not sure if it takes it back to the plates. I have bought and used what was probably 4NaEDTA from an auto parts store for quick fixing sulfated batteries, but there was a warning that the battery had to be recharged right away or it would wind up in worse shape than before.

Sodium sulfite is used to extend battery life, too.

I've just bought both some 4NaEDTA and NaSO2 from eBay for trials and testing.

Anyone here with experience or suggestions is welcome to speak up now before the stuff gets here late next week.

[WindriderNM]

I have used EDTA on some batteries that were given to me I have gotten about 4 years use from them they are starting to die again I  will retreat them again and see what happens. Someone else posted here a few years ago that they treated some dead batteries and got them working.

[dnix71]

WindriderNM how much EDTA did you use per cell? Did you cook the battery down, then add EDTA? How much can you dissolve in warm water?

[Madscientist267]

While I can't comment on the use of EDTA, I just want to point out that I've had limited results with pulse charging.

Not quite sure of the mechanism behind it, although I can follow a few theories.

Anyway, both pulse charging and discharging (ghurd controller for example) have given some interesting results from a few "testers" that I have experimented on.

Not that it applies here, but for anyone glancing at this in hopes of reviving an SLA with any of this. Stop right here, I can save you the trouble.

Only FLA have ever really been responsive.

Now, with all of that said, I'd be interested to see what the deal is if EDTA has sufficient effect that the two (or three, actually) concepts can be combined to give some really decent results.

One thing that bothers me about this however is this "battery must be recharged immediately" thing. One can take this a couple different ways - Does that mean you need to charge it immediately after adding it, then all will be ok? Or does it mean that you should have even less "dead" time than normal, lest one expect the thing to die a horrific death if discharged to any degree and left for more than a moment... ?

Food for thought. You're not the first one (by far) to mention EDTA, and pulse charging/discharging are not new concepts either.

Not saying experiment with all the variables on your bank at one time, but might be worth looking into this combination.

I know I wouldn't be the only one interested in the answer...

Steve

[WindriderNM]

It's been about four years since I did this. I don't remember how much I used, I got two jars on eBay and they were more than enough to do 12 six volt deep cycle batteries. I am going to order more soon, I am looking for a bulk supplier. I think I used about 1 or 2 tablespoons per cell, it didn't take very much warm water to dissolve the EDTA. at the time and made a lot of notes with the weight and amount of water needed and the amount I put in each cell. I have since misplaced the notes during a move.

[thirteen]

What does EDTA actually do to the cells?

[zvizdic]

>Obtain some EDTA (tetrasodium ethylenediaminetetraacetate or simply
>tetrasodium EDTA) from a chemical or lab supply place. This is a chelating
>agent and (I THINK) used on folks that are going to get an MRI scan.
 Four grams are added to each cell in an
>automotive battery. Agitate battery frequently for a few days (normal use
>will do). Finally, give the battery a thorough charge.
>

[jlt]

 Trailhead supply  has it they are located in Utah. And advertize in home power magazine .

[zvizdic]

"Magnesium Sulphate (Epsom Salts) - Can be bought at either the chemist or supermarket. Add a
slightly heaped teaspoonful into each cell. Fully charge it with a slow charge, then discharge it (use a
car headlight), then add another slightly heaped teaspoonful to each cell. It will take about a month
for the Epsom Salts to dissolve the sulphation and increase the battery's capacity to hold a charge."

It works 

[dnix71]

Started with it yesterday. I dissolved 2 pounds of Na4EDTA into about 4/5 gallon of distilled water. Using a kitchen measuring cup and a small funnel I added 2 ounces of solution to each cell. I still have a small amount of solution left over after treating 8 12v marine hybrid batteries.

That's when the "fun" began. The older batteries began fizzing and purcolating and the voltage of the whole string collapsed. My first thought was that I had just trashed my whole bank.

A 30 amp boost from a battery charger did very little, so I pulled the string apart and removed the 2 weakest batteries, one with about 12.3v and the other with 11.2v. I figured the 11.2v battery was history and was planning to replace it, but decided to wait one day to see if things recovered some. The 12.3v battery recovered to 12.45 and the 11.2v to 11.85v.

Both of those come up to 14v easily when connected to my van when running. I plan to add them back to the string tommorow. I have off work Wed-Fri so I can watch them charging once the sun comes up on my solar panels.

The 6 remaining had 12.8v at dusk after a day of solar charging and then settled to 12.6v so no damage was done. It looks like it's going to take a few charge cycles to rebalance the string. I have 5 lbs of NaSO2, but plan to wait a while before adding any of that.