VRLA battery

A VRLA battery ( valve -regulated English lead-acid battery) is a lead-acid battery in a sealed design. The accumulator includes a pressure control valve.

Features

Common characteristics of VRLA batteries are:

• The cells are welded, there is only one pressure relief valve.
• The electrolyte is concentrated, so no longer liquid, thus it is possible to operate permanently sealed lead-acid batteries in a lateral position, but when the plate sets are arranged vertically just to soak up the recombined water. Due to the capillary action of the electrolyte saturation of the upper layer is not guaranteed to be in the horizontal position of the plate sets. Lead-acid batteries can not be operated permanently "upside down " because of the safety valves, as an outlet of drip quantities of the electrolyte would then be possible. Temporary operating or storing in unusual positions, however, is not critical, so mail or an instant of equipment such as lawn mowers for maintenance is not a problem.
• In conventional lead-acid batteries must be regularly in the maintenance cells with distilled water in each cell, which evaporates during the gassing or heating and also modifies the acid concentration. This is not possible and not necessary with sealed batteries.
• Sealed lead-acid batteries gases significantly less than conventional: The fixed electrolyte through to gas channels are formed. The oxygen formed by the addition reaction at the positive electrode can therefore go directly to the negative electrode where they recombine to form water.
• Overcharging a sealed lead-acid battery, such as a defective charge controller, an excess of oxygen is produced which can not recombine. The same amount of hydrogen is produced at the negative electrode. Since replenishment of the electrolyte is not possible, thus requiring a sealed lead-acid batteries adapted charging method. It must be avoided that the battery is charged for a long time at a too high voltage is connected to high gassing. In this case, the gases escape through the pressure relief valve, and the accumulator can dry out over time; via the safety valves leaked gases can not be recombined. The valves have directionality and let no ventilation or recirculation of media. The use of catalytically active material is never used inside of a battery and is only possible for open vented systems, it is then used for gas drying to avoid external wetting.
• When charging with an excessive voltage, the risk of thermal runaway is in sealed lead-acid batteries: The internal oxygen cycle heats the battery. An increase in the battery temperature at a constant voltage leads to an increased charging current. This leads to increased gas evolution and the oxygen cycle is enhanced. This self-reinforcing process may overheat and damage the battery.

Acid battery

A Gelakkumulator is a design of the lead-acid battery in which, by the addition of silica (hence often: silicon -gel accumulator ) of the electrolyte ( liquid sulfuric acid) is bound. Because this type the accumulator is completely closed, it is therefore not possible to refill water. This type is also known as SLA battery (SLA = engl. Sealed lead acid ) respectively.

Specific properties of gel accumulators:

• There is practically no acid stratification that would otherwise be a relevant capacity loss due to separation causes with denser acid down, thinner above. In acid battery is compared to standard batteries decreases with liquid electrolyte and unbound at least.
• The internal resistance of gel lead acid batteries is higher than comparable non- sealed lead-acid batteries. They are therefore less suitable for delivering high currents, such as are required when used as a starter battery. For motorcycles, scooters and similar vehicles gel accumulators are, however, precisely because of their closed design very well available.

Absorbent Glass Mat ( AGM)

Absorbent Glass Mat (AGM ) is another design of the lead-acid battery in which the electrolyte is contained in a non-woven fiberglass. The common name for this is on the market VRLA AGM.

Fleece batteries can deliver high currents such as open versions of at least the same and are about as a starter battery in motorcycles, boats ( no acid leaking when tipping or capsizing ), vehicles with start -stop system and electric vehicles ( eg in CityEL ) used. Even with car hi-fi applications, these batteries are increasingly used. There one makes use of the lower internal resistance (compared to wet batteries ) advantage.

Leading manufacturers in the field of high start currents for automotive applications include Johnson Controls, Optima Batteries, Exide Batteries and banners.