Corrosion, Sulfation and Energy of Lead Acid Battery
Has been used more than 150 years, the lead acid battery is reliable, mature secondary batteries, globally manufactured and therefore a widely understood technology. They are commonly found in motor vehicles, battery backup systems and other electrical applications where a rechargeable battery is required. Almost any retailer that sells lead-acid batteries collects used batteries for recycling, as required by most state laws. Almost 90% of the lead-acid batteries are recycled.
How are the three main lead acid battery issues (grid corrosion, sulfation, and weight per unit of energy) addressed through Firefly’s new technology? Firefly’s technology specifically addresses all three critical areas for improvement.
Corrosion
The electrode material that Firefly has developed is not reactive in the lead acid environment and so does not corrode. There are several reasons for this. One is the inherent stability of the base material, and the other is the formation process used which maximizes exposure of the most chemically resistive surfaces and minimizes exposure of chemically less stable surfaces. This ability to configure the material in the formation process yields an excellent resistance to corrosion even in over-charging situations. Finally, since the carbon-graphite foam dissipates heat so effectively, and enables the chemistry to operate more uniformly, the battery operates cooler and more consistently and therefore the corrosion process is minimized in the 3D design and eliminated in the 3D2 design.
Sulfation
As we have seen, sulfation is caused by the precipitation of sulfite compounds that then coat the plates and block the conductive path required for recharging. Firefly’s patented foam plates contain specific amounts of active material, which are in balance with the electrolyte and are localized within a very specific area. In other words, the largest that a sulfate crystal can grow is related to the available amount of active material. Even if the entire amount of active material within any single restriction were converted into a single sulfate crystal, it would be small enough and close enough to the carbon-graphite electrode to convert back during recharge. In short, the composition and configuration of Firefly’s plates yield a much higher resistance to the effects of sulfation.
Energy Density
As we have indicated, the real quest for performance improvements in lead acid batteries is about surface area, the ability of the positive plates to capture the maximum number of electrons from the chemical reaction taking place and conduct them toward the positive terminal. The overwhelming restriction to lead acid battery chemistry has always been the lack of interface area between the active chemistry and the electrodes. Because of the corrosion issues that we discussed, there’s a severe limitation to the amount of surface area that can be made available on a positive grid without compromising its structural integrity.
Firefly technology increases surface area enormously and efficiency is greatly increased. Not only does this yield higher power output in Whr/kg, but there are other advantages as well. Charge and discharge times can be faster, and a higher percentage of active material is accessible so overall efficiency goes up.
Nowadays, compared with the new energy technologies which are now sweeping the world, however, lead acid batteries have to be admitted that they look old-fashioned and a bit frumpy. But from another perspective, the lead acid battery is tired and trusted, and it just needs a bit of pepping up. In the future, lead acid batteries are still the major batteries in many applications. With constant improvement, they will have better future all over the world.
Simple Guidelines:
- Always store lead-acid in a charged condition. Never allow the open cell voltage to drop much below 2.10V. Apply a topping charge every six months or when recommended.
- Avoid repeated deep discharges. Charge more often. Use a larger battery to reduce the depth of discharge.
- Prevent sulfation and grid corrosion by choosing the correct charge and float voltages. If possible, allow a fully saturated charge of 14h.
- To reverse sulfation, raise the charge voltage above 2.40V/cell for a few hours.
- Avoid operating lead-acid at elevated ambient temperatures.
Source: www.leoch.com
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