[Antelpebabe]

The battery in one of our cars is maybe 4 years old and while it is not bad, it is not as good as it used to be. There is advertised stuff like this --> http://www.jaycar.com.au/productView.asp?ID=NA1420 that is supposed to dissolve the lead sulphate off the negative plates and if the battery is still mechanically sound, i.e. the plates have not crumbled to a mush or the paste has not come away from the lead grid through too much swelling and contraction, then it may improve the condition of the battery. The MSDS says it contains ~5% cadmium sulphate. This all sounds good to me but I am not an electrochemist. Do these things really have a hope of working?

[gariharrr]

Maybe?
The usual method is using a suitable charger designed for the purpose.

There are two types of sulfation: reversible (or soft sulfation), and permanent (or hard sulfation). If a battery is serviced early, reversible sulfation can often be corrected by applying an overcharge to a fully charged battery in the form of a regulated current of about 200mA. The battery terminal voltage is allowed to rise to between 2.50 and 2.66V/cell (15 and 16V on a 12V mono block) for about 24 hours. Increasing the battery temperature to 50–60°C (122–140°F) further helps in dissolving the crystals. Permanent sulfation sets in when the battery has been in a low state-of-charge for weeks or months. At this stage, no form of restoration is possible.
So the additive may help with hard sulphation.

Battery Uni.

[Nppracph]

How do you get the lead sulfate paste off the bottom of the casing back into solution allowing the redepositioning of the lead in the lead sulfate back onto the metal grid for battery reconditioning?

You face an uphill struggle to get the precipitated lead sulfate paste back into a solution that is already effectively saturated. You could drive to deposit the lead onto the grid, reducing the lead ions in solution, improving your solubility product, but hydrogen production may make this explosive and dangerous. Addition of sulfate would work against this as well, IMHO.

[Nashhlkq]

can't you only get Magic Additive from the testicles of an enraged Unicorn?

[sPncEjF7]

The battery doesn't have separate exposed caps but a rectangular cover over the top of the set of six. It was glued down so I tried to prise it off and I think I might have broken the stupid battery. I had hosed the thing down before I started work on it, and now when you tilt it up a bit something like water or acid runs out. Can't tell at this point.

Somedays it just doesn't pay to try anything.

[bushomeworkk]

The battery doesn't have separate exposed caps but a rectangular cover over the top of the set of six. It was glued down so I tried to prise it off and I think I might have broken the stupid battery. I had hosed the thing down before I started work on it, and now when you tilt it up a bit something like water or acid runs out. Can't tell at this point.

Somedays it just doesn't pay to try anything.

It sounds like the battery was pretty well stuffed anyway so you havent done anything but hasten the process. Silicon will probably seal it up again.

[panholio]

If you still had the old unsealed type battery, you could simply have drained off the fluid, allowed it to settle and poured the fluid back in sans the precipitates. This did give them extra mileage.

[Hankie]

can't you only get Magic Additive from the testicles of an enraged Unicorn?

Well they get really enraged when you grab them ...

[qCGfQR9T]

Cadmium Sulphite works well in extending the working life of lead acid batteries, more particularly those with low duty cycles. Should be installed in batts when new. Battery companies generally deny it works, or void warranties, because it ultimately means less sales. Sealed batteries [no maintenance] should not be dismantled to install it, as the battery is usually badly mechanically damaged. Car battery life have been observed to be upto 7 yrs with this additive, whereas a car battery is usually only good for 4 yrs. IE Battery warranty is a con. You pay more to get 4 yrs on the same 2 yr battery, and it's only pro-rata. Love of money........

Spending $10- on a terminal battery is rarely cost effective, IMHO.

[smirnoffdear]

Cadmium Sulphite works well in extending the working life of lead acid batteries, more particularly those with low duty cycles. Should be installed in batts when new. Battery companies generally deny it works, or void warranties, because it ultimately means less sales. Sealed batteries [no maintenance] should not be dismantled to install it, as the battery is usually badly mechanically damaged. Car battery life have been observed to be upto 7 yrs with this additive, whereas a car battery is usually only good for 4 yrs. IE Battery warranty is a con. You pay more to get 4 yrs on the same 2 yr battery, and it's only pro-rata. Love of money........

Spending $10- on a terminal battery is rarely cost effective, IMHO.

Do you mean Cadmium sulfite? or Cadmium sulfate? Do you know the difference?

[Hpdovoxm]

I've tried this years ago with the additive tablets that I think are based on Epsom salt.

There are some related tips here http://www.ehow.com/how_4855050_reco...tery-home.html
and in a video here http://www.youtube.com/watch?v=xfIPNjX8W7E
and http://batteryuniversity.com/learn/article/additives

My experience was that there was very little noticeable difference. After a few weeks I gave up and replaced the battery. Usually it's at the beginning of cold weather when you notice the turnover is slow, and it just gets worse as the weather gets worse.

The best thing you can to do extend battery life is to make sure it's always charged according to guidelines for the battery technology. The manufacturers usually have application notes available that go into great detail. Lead-acid batteries need to be charged with a carefully regulated voltage which may also need to be adjusted for temperature. Allowing the cells to go over voltage results in outgassing which is bad for the cells and can cause explosions. Charging under voltage because of the nature of the cell results in insufficient charge. Allowing lead acid cells to drop below a certain voltage encourages rapid sulfation and drastic loss of capacity, so it is essential to maintain their charge, keeping checks on batteries in storage and applying a top-up charge at intervals. Driving habits where you make short trips without any longer trips that allow the battery to properly recharge can shorten the life of the battery (as well as fouling spark plugs) - it can take approx 20 times the starter turning time which of course can vary. Could be up to 10-15 minutes to ensure a full charge. If a battery is already run down it could take 30 minutes, and you normally need to be running at normal RPM, not idle RPM.

[AndyScouchek]

Around the 3-4years age some extra capacity can be got by giving them a good charge, something above what the car alternator comes around to when it senses the battery is fully charged. 13.9Volts for maybe few days would do it, or maybe around fifteen volts for few hours, or something between those figures. I've done it a few times. Generally batteries start to flag into winter, the cold itself reduces capacity and engines take a bit more cranking power, plus those short drives down to the deli for chocolate don't allow proper charging and the battery sits partially discharged a lot increasing sulfation.

http://en.wikipedia.org/wiki/Sulfation_(Battery)

"Lead–acid batteries lose the ability to accept a charge when discharged for too long due to sulfation, the crystallization of lead sulfate. They generate electricity through a double sulfate chemical reaction. Lead and lead dioxide, the active materials on the battery's plates, react with sulfuric acid in the electrolyte to form lead sulfate. The lead sulfate first forms in a finely divided, amorphous state, and easily reverts to lead, lead dioxide and sulfuric acid when the battery recharges. As batteries cycle through numerous discharges and charges, some lead sulfate is not recombined into electrolyte and slowly converts to a stable crystalline form that no longer dissolves on recharging. Thus, not all the lead is returned to the battery plates, and the amount of usable active material necessary for electricity generation declines over time.

Sulfation occurs in all lead–acid batteries during normal operation. It impedes recharging; sulfate deposits ultimately expand, cracking the plates and destroying the battery. Eventually so much of the battery plate area is unable to supply current that the battery capacity is greatly reduced. In addition, the sulfate portion (of the lead sulfate) is not returned to the electrolyte as sulfuric acid. The large crystals physically block the electrolyte from entering the pores of the plates. Sulfation can be avoided if the battery is fully recharged immediately after a discharge cycle.[15] A white coating on the plates may be visible (in batteries with clear cases, or after dismantling the battery). Batteries that are sulfated show a high internal resistance and can deliver only a small fraction of normal discharge current.

Sulfation also affects the charging cycle, resulting in longer charging times, less efficient and incomplete charging, and higher battery temperatures.

The process can often be at least partially reversed by a desulfation technique called pulse conditioning, in which short but powerful current surges are repeatedly sent through the damaged battery. Over time, this procedure tends to break down and dissolve the sulfate crystals, restoring some capacity.[16]

Desulfation is the process of reversing the sulfation of a lead-acid battery. Desulfation is achieved by high current pulses produced between the terminals of the battery. This technique, also called pulse conditioning, breaks down the sulfate crystals that are formed on the battery plates. Short high current pulses tend to work best. Electronic circuits are used to regulate the pulses of different widths and frequency of high current pulses. These can also be used to automate the process since it takes a long period of time to desulfate a battery fully. Battery chargers designed for desulfating lead-acid batteries are commercially available. A battery will be unrecoverable if the active material has been lost from the plates, or if the plates are bent due to over temperature or over charging.

Batteries which have sat unused for long periods of time can be prime candidates for desulfation. A long period of self-discharge allows the sulfate crystals to form and become very large. Some typical cases where lead acid batteries are not used frequently enough are planes, boats (esp sail boats), old cars, and home power systems with battery banks that are under utilized.

Some charging techniques can aid in prevention such as equalization charging and cycles through discharging and charging regularly. It is recommended to follow battery manufacturer instructions for proper charging.

SLI batteries (starting, lighting, ignition; i.e. car batteries) have less deterioration because they are used more frequently vs deep cycle batteries. Deep cycle batteries tend to require more desulfation, can suffer from overcharging, and can be in a very large bank which leads to unequal charging and discharging"

[jokilewqs]

Cadmium Sulfite-yes!

[RozzyLiu]

Probably can't beat a regular equalization charge, and not letting the battery sit around in a low state of charge.

A charger of some sort that keeps the battery around 13.2 Volts while not in use would probably extend life.

[Bondjrno]

Ask Telstra and Navy how they keep their lead acid batteries long term. I remember the 1100AH 2.2V cells all joined together in the battery rooms, 2x 50V battery banks, feeding a 1600A busbar [abt 6"x1/2" copper bar(s) AFAIR] @ Bathurst St exchange-Hobart. Legend has it that a spanner could be melted by shorting it across the battery. I don't have proof anyone did so, but the comment was common that doing so at the end of the bus would NOT blow the 2000A fuse near the batteries. A new genset was installed whilst I was there. I remember watching the staff commission & debug the new buck/boost charging system. Crude, but it eventually worked.

[Saispapedlimi]

I worked in City West Exchange in Melbourne as my first posting, The equipment aisles were fairly dark places so over time the fluorescent lights had been taken off their chains and just sat across the tops of the aisles. along the top of each aisle were the busbars 2" by about 3/8" copper insulated with painted cardboard, the lights were sitting on them and needed to be shoved out of the way if you needed to work at the top of the rack, by 1969 when I worked there the exchange was fairly old and the cardboard insulation was pretty flakey so it was only a matter of time before someone vapourised a fluoro light shade very spectacular and put half the exchange off for a few minutes.

[PheliarearY]

Cadmium Sulfite-yes!

That is a relatively rare, expensive and labile chemical compared with the cadmium sulfate that is mentioned in the patent literature and in most descriptions of additives. It is a reducing agent and will grab oxygen from wherever it can to turn itself into sulfate.

[jimmy28]

Ask Telstra ... how they keep their lead acid batteries long term.

Always kept on float charge. Twenty years or more was common for the flooded cells.
Legend has it that a spanner could be melted by shorting it across the battery. I don't have proof anyone did so, but the comment was common that doing so at the end of the bus would NOT blow the 2000A fuse near the batteries. I've heard that one too. Allegedly there was nothing left of said spanner as it was vapourised.

[ligaliaCods]

Just to add to the excellent wiki information, the three sets of components in the electrochemical cells for the battery are Lead (s) (metal), lead (II) sulfate and lead (IV) sulfate.

I am not at my usual place, so do not have my SI Chem Data ready at hand to give solution equilibrium constants. These numbers give indication as to the solubility of the lead salts (lead(II)sulfate and lead(IV)sulfate)

Keeping your battery bottom warm (or not freezing is the best way to not have the mainly lead(IV) sulfate precipitate (the crystallising salts in the Wiki). It is this that is the very very difficult thing to get back into solution and it causes the lead metal to be decayed off the metal electrode.

I am careful of experimenting with the conditions to regenerate a "dead" battery, but would think warming to 50 or 60C may assist in the solubility of lead sulfate salts (of lead(II) and lead(IV) types). Over voltage recharging may assist in the redepositioning of the reduced lead metal back onto the plate electrode, but you will be running a very high chance of a hydrogen gas build up. You will need to monitor the fluid levels as the excess heat and electrolysis of the water will; work to evaporate and lower the fluid level.

The use of the lead acid battery as an example for half cells and electrochemistry is very neat as people sort often get to see these regularly in life.

[occurrini]

... but you will be running a very high chance of a hydrogen gas build up. You will need to monitor the fluid levels as the excess heat and electrolysis of the water will; work to evaporate and lower the fluid level.

So it's something that you can try with an older type battery where you can remove the caps for the cells to top up the water level, but not something to try on a sealed/maintenace free battery.