Solar battery Victron Energy GEL 220Ah

The Victron 220 Ah deep cycle VRLA GEL lead-acid battery with advanced electrolyte bonding technology on silica gel brings a number of indisputable advantages over conventional liquid electrolyte batteries. The most important of these are absolute maintenance-free operation over the entire service life, low self-discharge rate, temperature stability, high resistance to deep discharge and subsequent rapid "recovery", reduced influence of vibration and mechanical damage to the gel-fixed plates, non-leaching of the electrolyte with all its negatives, and low electrode corrosion and sulfation.

Victron Energy's gel batteries are designed for smaller off-grid solar photovoltaic applications, such as powering cottages and other off-grid buildings with seasonal operation. For use in hybrid systems with daily cyclic operation, OPzS, OPzV or lithium batteries with significantly higher cycling resistance are much more suitable.

VRLA technology

The universal abbreviation VRLA refers to Valve Regulated Lead Acid (VRLA) batteries. The battery pack is completely sealed and without inspection holes for checking the electrolyte. Gas can potentially escape only through safety relief valves if the battery is significantly overcharged or one or more cells are damaged. The electrolyte cannot be topped up from the battery.

Electrolyte bound in gel

The electrolyte is bound by adhesive forces in the capillaries of the silica gel, which acts as a carrier. Due to the binding of the electrolyte in the gel and the non-corrosive plastic housing, the risk of acid leakage is zero. Due to the closed construction, vapour leakage is minimised, which makes the batteries suitable for use in living quarters (e.g. caravans).

Low self-discharge

Every battery undergoes a natural process of self-discharge and a decrease in the amount of stored energy. The self-discharge rate is an important parameter, especially in systems with very long charging intervals or when the battery is stored and not used. By using high purity materials and enriching the lead plates with calcium, the self-discharge process is minimized. The self-discharge rate is less than 2% of the total capacity per month at 20 °C. Each 10 °C increase in temperature doubles the self-discharge rate. If a fully charged battery is stored at low temperatures (not freezing), it does not need to be recharged in any way for approximately one year without damage.

Deep discharge resistance

Every discharge damages any lead acid battery. The degree of damage is determined by the depth and duration of the discharge. Victron energy gel batteries are no exception in this respect. However, Victron energy gel batteries are extremely resistant to the effects of deep discharge and the effects of its long duration.

Discharge characteristics

Battery capacity is not a stable value. It depends mainly on the magnitude of the discharge current. The stated capacity of 220 Ah refers to a discharge time of 20 hours with a final discharge voltage of 10.8 V. In other words, the stated capacity is valid if the battery is discharged for twenty hours with a current of 0.05 x the stated capacity, i.e. 0.05 x 220 Ah = 11 A. The smaller this current is, the more energy we get from the battery and vice versa. The table below shows the dependence of the discharge duration (current magnitude) on the usable capacity of the battery.  However, due to the design of gel batteries, the effect of large discharge currents on the total capacity of the battery is relatively small. In the context of sealed battery types, they also tolerate large current surges due to low internal resistance (e.g. starting) in an excellent manner.

Lifetime

Cycle life: 500 cycles at 80% discharge, 750 cycles at 50% discharge and1800 cycles at 30% discharge. Lifetime 12 years in float operation at 20 °C. The battery is suitable for both cyclic operation (charge-discharge) and continuous charging with a low discharge rate.

Charging

We recommend standard adaptive three or four phase charging (bulk=BULK, absorption=ADSORPTION, maintenance=FLOAT and possibly storage phase=STORAGE). The battery is not designed to be charged at constant voltage and current, there is a risk of overcharging and gas generation. Recommended charging voltage values are given in the technical data below. The charging current should not exceed 20% of the battery capacity. Temperature compensation of the charging voltage is recommended at temperatures below 10°C or above 30°C. The charging voltage should be reduced at higher temperatures and increased at lower temperatures. A temperature compensation value of 4 mV per cell and a one-step temperature deviation from the standard 20 °C is recommended. Compensation is recommended especially at high charging currents.

With all these advantages and features, gel batteries are extremely favourable for smaller off-grid solar photovoltaic applications such as powering cottages and other off-grid buildings. Compared to conventional batteries with liquid electrolyte, gel batteries are more susceptible to overcharging. This is easily solved with a suitable solar controller or adaptive charger, but this is now standard.

In the documents in the annex this battery is referred to as "Gel Deep Cycle".