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Gel and AGM Batteries

Gel and AGM Batteries
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1. VRLA technology VRLA stands for Valve Regulated Lead Acid, which means that the batteries are sealed. Gas will escape through the safety valves only in case of overcharging or cell failure. VRLA batteries are maintenance free for life. 2. Sealed (VRLA) AGM Batteries AGM stands for Absorbent Glass Mat. In these batteries the electrolyte is absorbed into a glass-fibre mat between the plates by capillary action. As explained in our book 'Energy Unlimited', AGM batteries are more suitable for short-time delivery of high currents than gel batteries. 3. Sealed (VRLA) Gel Batteries Here the electrolyte is immobilized as gel. Gel batteries in general have a longer service life and better cycle capacity than AGM batteries. 4. Low Self-Discharge Because of the use of lead calcium grids and high purity materials, Victron VRLA batteries can be stored during long periods of time without recharge. The rate of self-discharge is less than 2% per month at 20°C. The self-discharge doubles for every increase in temperature by 10°C. Victron VRLA batteries can therefore be stored for up to a year without recharging, if kept under cool conditions. 5. Exceptional Deep Discharge Recovery Victron VRLA batteries have exceptional discharge recovery, even after deep or prolonged discharge. Nevertheless repeatedly deep and prolonged discharge has a very negative effect on the service life of all lead acid batteries, Victron batteries are no exception. 6. Battery Discharging Characteristics The rated capacity of Victron AGM and Gel Deep Cycle batteries refers to 20 hour discharge, in other words: a discharge current of 0,05 C. The rated capacity of Victron Tubular Plate Long Life batteries refers to 10 hours discharge. The effective capacity decreases with increasing discharge current (see table 1). Please note that the capacity reduction will be even faster in case of a constant power load, such as an inverter. Table 2: Design service life of Victron batteries under float service victron energy BLUE POWER Victron Energy B.V. | De Paal 35 | 1351 JG Almere | The Netherlands General phone: +31 (0)36 535 97 00 | E-mail: sales@victronenergy.com www.victronenergy.co

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8. Effect of temperature on capacity As is shown by the graph below, capacity reduces sharply at low temperatures. Temperature (°C) Fig. 1: Effect of temperature on capacity 9. Cycle life of Victron batteries Batteries age due to discharging and recharging. The number of cycles depends on the depth of discharge, as is shown in figure 2. Gel Deep Cycle Charge current Charge voltage 10. Battery charging in case of cycle use: the 3-step charge curve The most common charge curve used to charge VRLA batteries in case of cyclic use is the 3-step charge curve, whereby a constant current phase (the...

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Disadvantages of the traditional 3-step charge curve: • During the bulk phase the current is kept at a constant and often high level, even after the gassing voltage (14,34V for a 12V battery) has been exceeded. This can lead to excessive gas pressure in the battery. Some gas will escape through the safety valves, reducing service life. • Thereafter the absorption voltage is applied during a fixed period of time, irrespective of how deep the battery has been discharged previously. A full absorption period after a shallow discharge will overcharge the battery, again reducing service life...

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victron energy LUE POWER Table 3: Recommended charge voltage 12 Volt Deep Cycle GEL 2 Volt Long Life GEL Other capacities and terminal types: at request Victron Energy B.V. | De Paal 35 | 1351 JG Almere | The Netherlands General phone: +31 (0)36 535 97 00 | E-mail: sales@victronenergy.com www.victronenergy.com victron energy BLUE POWER

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