1A/310 Boundary Road Dingley Village VIC 3172 03-95873200 mrsolar@mrsolar.com.au

Deep Cell Batteries

With suitable solar units and battery systems the free energy from the sun produces power independently. This is especially advantageous in regions where there is no wide coverage by the electrical grid infrastructure or where the connection to the gird is uneconomical.

Solar Batteries cover a versatile spectrum of possible applications:

Solar power stations telecommunications systems measurement stations street lighting alarm systems sterilisation plant

information signs parking ticket machines radio emergency telephones traffic light systems week-end and holiday homes

hunting lodges mobile site offices caravans ships maritime buoys

What is a gel cell?

A gel cell is a lead-acid electric storage battery that:

	is pressurized and sealed using special valves and therefore should never be opened
	is completely maintenance free (Connections must be retorqued and the batteries should be cleaned periodically)
	uses a thixotropic gelled electrolyte
	uses the 'recombination' technique to replace oxygen and hydrogen normally lost in a wet cell (particularly in deep cycle applications)
	is non-spillable, and therefore can be operated in virtually any position. However, installation upside down in not recommended.

How does a gel cell work?

A gel cell is a 'recombinant' battery. This means that the oxygen that is normally produced on the positive place in all lead-acid batteries recombines with the hydrogen given off by the negative plate. The recombination of hydrogen and oxygen produces water (H²0), which replaces the moisture in the battery. Therefore the battery is maintenance-free, as it never needs watering.

The oxygen is trapped in the cell by special pressurized sealing vents. It travels to the negative plate through tiny fissures or cracks in the gelled electrolyte.

The sealing vent is critical to the performance of the gel cell. The cell must maintain a positive internal pressure. Otherwise the recombination of the gasses will not take place and the cell will dry out and not perform.

In addition, the valve must safely release any excess pressure that may be produced during overcharging. Otherwise the cell would be irreparably damaged.

It is important to note that a gel cell must never be opened once in leaves the factory. If opened, the cell loses its pressure and the outside air will 'poison' the plates and cause an imbalance that destroys the recombination chemistry.

Sealed gel technology (commonly referred to as 'gel cell' technology) was developed several years ago. Over the years, the gel battery has evolved and developed into the battery of choice for discriminating system designers, application engineers and sophisticated users.

Gel cells can be used in virtually any flooded electrolyte wet cell application (in conjunction with well-regulated charging) as well as applications where traditional wet cells cannot be used. Because of their unique features and benefits, gel cells are particularly well suited for:

What is the difference between gel cell and traditional wet batteries?

Wet cells do not have special pressurized sealing vents, as they do not work on the recombination principle. They contain liquid electrolyte that can cause corrosion and spill if tipped or punctured. Therefore, they are not air transportable without special containers. They cannot be used near sensitive equipment They can only be installed upright.

Wet cells lose capacity and become permanently damaged if left in a discharged condition for any length of time (due to sulfation) or continually over-discharged due to active material shedding.

Deep cycle antimony wet cells have seven times less shelf life as well. Gel cells have triple the deep cycle life of wet cell antimony alloy deep cycle batteries due to the unique design.

Why Choose gel batteries for Solar applications

	Acid immobilised in a silica gel compound Batteries can be easily transported at installation or disposal No need for delicate handling procedures or filling / emptying at site - Reduced installation and disposal cost  and time Acid cannot stratify No need for monthly, long, energy wasting high voltage equalising charging - Reduced running costs and panel size Tolerant to vibration Easily transported Safe for use near generator and / or non-solid floors - reduced building costs Acid cannot spill from cracked battery or splash when filling. No danger to children or maintenance personnel
	Simple charging procedure No need for expensive or complicated regulators No need for regular boost charging
	Safe for all transport, including air No need for special transport considerations Can be sent ready for use at remote sites Reduced freight and handling costs
	Supplied filled and charged No need for filling and special start-up charging - reduced installation time and cost
	Can sustain higher Depths of Discharge Battery bank size can generally be halved - cost of battery bank is reduced
	Fully Recyclable No special disposal procedure, no need to empty the acid - low end of life cost
	Can tolerate 100% Discharge Batteries will fully recover from deep discharge - without any damage or capacity loss Batteries can be 100% discharged if extra temporary demands are place on the system (i.e. generator or regulator failure, guests arriving or no sun) Safeguard against damage when abused Greatly reduces frequency of battery replacements
	Can be deeply discharged for up to four weeks Batteries will recover even after being left flat for a month Safeguard against damage Reduces service calls and battery replacements
	No need for separate battery room Can be installed indoors without eyewash, acid resistant flooring, forced ventilation etc (required for AS3011.1 and AS2676.1 when using wet batteries) Can control the auxiliary equipment (regulator, inverter etc) adjacent to batteries as no acid is in the atmosphere. Reduced building and battery room costs.
	No maintenance Batteries are fully sealed and never require 'topping up' Site requires no monthly maintenance or inspections (six monthly required) Site can be left for long periods Worry free operation if leaving the site for some time (i.e. Holidays, mountain top) Reduced maintenance time and cost (and stress)
	Low Peukert coefficient (high charge / discharge rate efficiency) 'Shrinkage of the battery bank capacity at high loads is minimal Large battery banks can be avoided Higher voltages under heavy loads Better efficiency means shorter recharge times Higher inverter efficiency and reduced battery bank size Further cost savings from reduced generator run times
	Low self discharge Can be left for up to two years without recharging (at 20OC) Much lower requirements from the solar panels to keep the batteries 'top up' charged - reduces solar panel sizing