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Troubled Cells Richard Perez
Here is what to do when the ole' battery is not storing what she used to. Many troubled batteries
can have their capacity restored through healing procedures. These procedures vary from a series of overcharges to radical chemical surgery.
First make sure that the patient is really sick
In HP #28, page 36 I wrote an article about diagnosing battery problems. If you haven't read this article, then please do so before attempting to heal your battery. Chances are that your battery only needs to be fully recharged. The healing procedures in this article are only for sick cells. Performing these procedures on heathy cells will not improve their ability to store electric power. If your battery is already in good shape, then these procedures will only waste time, money, and materials. The procedures here are for sick cells, not dead cells. These procedures will not cure cells with internal short circuits, internal open circuits, or foreign material contamination.
The biggest problem in lead-acid cells is sulfation due to chronic undercharging. Here the sulfate ions have entered into deep bonds with the lead on the cell's plates. The sulfate ions can bond with the lead at three successively deeper energy levels. Level One is the bond we use when we normally charge and discharge the cell. After a month or so at Level One, some of the bonds form Level Two bonds which require more electric power to break. After several months of being Level Two bond, the sulfate ions really cozy up to the lead and form Level Three bonds. Level Three bonds are not accessible electrically. No amount of recharging will break Level Three bonds. The longer the lead sulfate bond stays at a level the more likely it is to form a closer acquaintance and enter the next deeper level. This is why it is so important to fully, regularly, and completely, recharge lead-acid cells.
44 Home Power #29 • June / July 1992
Dante's Guide to Lead-Acids
If the loss in capacity is due to Level Two bonding, then a repeated series of equalizing charges will break the Level Two bonds. Under equalization the Level Two bonds will first be transformed into Level One bonds, and then the sulfate ion can be kicked loose of the lead entirely and reenter the electrolyte solution.
If your lead-acid cells have lost capacity, then a regime of equalizing charges is the first procedure to try. An equalization charge is a controlled overcharge of an already fully recharged cell. First recharge the cell and then continue to charge the cell at a C/20 rate for five to seven hours. During equalization charges, the cell voltage will become very high, about 2.7 VDC per cell. This overcharge contains the necessary power to break the Level Two bonds and force them to Level One. Once they reach Level One, the bond is easily broken and the sulfate ions reenter into solution in the electrolyte.
If a bond spends several months at Level Two, it eventually enters the depths of Level Three. The Level Three bonds must be chemically stripped from the plates. This is a job for an organic acid called EDTA, a close chemical cousin of vinegar. EDTA stands for the compound "ETHYLENEDIAMINE TETRAACETIC" Acid. In chemical techie terms, EDTA is a "chelating agent." EDTA comes in several forms. Use the tetraacetic variety.
The EDTA procedure is simple. Use one tablespoon of the EDTA powder for each quart of electrolyte in the cell. Mix the EDTA with a small amount (an ounce or two) of distilled water and add it to the cell. Recharge the cell and give it an equalizing charge. Recharging the cell speeds up the reaction and allows the EDTA to strip the Level Three bonds from the surface of the cell's plates. After
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