The name "gel cell" refers to the fact that this gel battery uses a gelled electrolyte rather than a liquid one. It is a type of SLA or sealed lead acid battery. In true Gel cells, the sulphuric acid electrolyte is thickened (gelled) to allow the battery to work in all positions. Unfortunately this electrolyte thickening decreases the mobility of the ions which results in increased internal resistance. There are other differences resulting from gelling, the most significant detriment is that the electrolyte can not be removed. Washing out of the cells to help rejuvenate the battery in true gel cells are just not possible. Sealed lead acid batteries also cost much more then ordinary wet cell types. Presently the very common seven Ampere hours sealed cell battery cost more than twice as much as a new garden tractor battery which has three time the AHr's capacity.
Almost all smaller (up to about 1000VA) UPS, used by many personal computer users are outfitted with these sealed type batteries. Smaller UPS uses one, larger ones use two or more. The UPS continually "float" charge its batteries. Typical float charge for the seven AHr batteries is around 50+-mA. Most UPS supplies continuously charge the internal sealed cell battery, as long as the UPS unit is plugged into a working wall outlet. The float charger is applied even when the power switch is in the "off" position. As a result of this charging the internal battery will be fully ready for any forthcoming emergency. It is precisely what is required to keep the battery's cells from sulfation, a nonreversible serious degradation. Reconverting these lead sulphate crystals are not easy even in conventional lead acid batteries.
When the battery reaches full charge, the continued flow of current disassociate the water in the electrolyte into its gaseous components-hydrogen and oxygen. In the course of a short few years, this nonstop charging action results in completely dehydrated, dried up cells. UPS manuals advise users to frequently test their units. Occasionally, on more expensive power supplies, a test button is provided for this purpose. As water loss and the battery's internal resistance gradually increases, its Ampere hour capacity steadily decreases. This loss is apparent in shorter and shorter backup times. Since backup batteries are "sealed" units, replace them may be the only apparent remedy. Then the same cycle repeats again. Usually the life time of a sealed battery in UPS service is between two to four years. Precisely, because of the high replacement cost, and to protect our overburdened fragile environment, it is most advantages to extend life of those batteries as much as possible. A small time spends on maintenance pays good dividends, not only in cost avoidance, but improved emergency readiness as well. Revitalization of these sealed cells is best done, as preventive maintenance, before they are complete dry up.
If you want to know more about gel battery, you can just visit Leoch International, which is an excellent manufacturer of lead acid battery. The company is a public company which has over 10 year's history and it is very reliable and dependable. If you are interested in the company, you can search for more information in the internet. The office website is http://www.leoch.com.