Baterías

Gel and AGM Batteries
Energy Unlimited www.victronenergy.com 1. VRLA technology VRLA stands for Valve Regulated Lead Acid, which means the batteries are sealed. Gas will escape through the safety valves only in case of overcharging or cell failure. VRLA batteries have exceptional leak resistance, and can be used in any position. VRLA batteries are maintenance free for life. 2. Sealed (VRLA) AGMbatteries 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 very high currents (engine starting) than gel batteries. 3. Sealed (VRLA) Gel batteries Here the electrolyte is immobilized as gel. Gelbatteries 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 with 10°C.Victron VRLA batteries can therefore be stored during 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. It should however be stressed that repetitive deep discharge and prolonged discharge have a very negative influence on the service life of alllead 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 (seetable 1). Please note that the capacity reduction will be even faster in case of a constant power load, such as an inverter.
Discharg time (constant current) 20 hours 10 hours 5 hours 3 hours 1 hour 30 min. 15 min. 10 min. 5 min. 5 seconds End Voltage V 10,8 10,8 10,8 10,8 9,6 9,6 9,6 9,6 9,6 AGM ‘Deep Cycle’ % 100 92 85 78 65 55 42 38 27 8C Gel ‘Deep Cycle’ % 100 87 80 73 61 51 38 34 24 7C Gel‘Long Life’ % 112 100 94 79 63 45 29 21

Table 1: Effective capacity as a function of discharge time (the lowest row gives the maximum allowable 5 seconds discharge current) Our AGM deep cycle batteries have excellent high current performance and are therefore recommended for high current applications such as engine starting. Due to their construction, Gel batteries have a lower effective capacity athigh discharge currents. On the other hand, Gel batteries have a longer service life, both under float and cycling conditions. 7. Effect of temperature on service life High temperature has a very negative effect on service life. The service life of Victron batteries as a function of temperature is shown in table 2.
AGM Deep Cycle years 7 - 10 4 2 Gel Deep Cycle years 12 6 3 Gel Long Life years20 10 5

Average Temperature

20° / 68° C F 30° / 86° C F 40° / 104° C F

Table 2: Design service life of Victron batteries under float service

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8. Effect of temperature on capacity As is shown by the graph below, capacity reduces sharply at low temperatures.

Fig. 1: Effect of temperature on capacity 9. Cycle life of Victron batteries Batteries age due todischarging and recharging. The number of cycles depends on the depth of discharge, as is shown in figure 2. AGM Deep Cycle Gel Deep Cycle Gel Long Life

Depth of discharge Fig. 2: Cycle life 10. Battery charging in case of cycle use: the 3-step charge characteristic The most common charge curve used to charge VRLA batteries in case of cyclic use is the 3-step charge characteristic, whereby a...