Product Knowledge

The newer type of sealed, nonspillable, maintenance free valve regulated battery.Uses “Absorbed Glass Mats”, or AGM separators between the plates. These are very fine fiber Boron-Silicate glass mats. This type of the battery has all the advantages of Gel batteries but can take much more abuse. These batteries are also called “starved” electrolyte batteries.Just like the Gel batteries the AGM Battery will not leak acid if broken.

The advantages of AGM batteries are: no maintenance, non-spilling even if they are broken, sealed against fumes, hydrogen, leakage, and can survive most freezes. AGM batteries are “recombinant” which means the Oxygen and Hydrogen recombine inside the battery. These use gas phase transfer of oxygen to the negative plates to recombine them back into water while charging and prevent the loss of water through electrolysis. The recombining is typically 99+% efficient, so almost no water is lost. Charging voltages for most AGM batteries are the same as for a standard type battery so there is no need for special charging adjustments or problems with incompatible chargers or charge controls. Since the internal resistance is extremely low, there is almost no heating of the battery even under heavy charge and discharge currents. AGM batteries have a very low self-discharge rate (from 1% to 3% per month). So they can sit in storage for much longer periods without charging. The plates in AGM’s are tightly packed and rigidly mounted and will withstand shock and vibration better than any standard battery.

All sealed lead acid batteries self-discharge. If the capacity loss due to self-discharge is not compensated for by recharging, the battery capacity may become unrecoverable. Temperature also plays a role in determining the shelf life of a battery. Batteries are best stored at 20℃. When batteries are stored in areas where the ambient temperature varies, self-discharge can be greatly increased. Check the batteries every three months or so and charge if necessary.

A Gel battery design is typically a modification of the standard lead acid automotive or marine battery. A gelling agent is added to the electrolyte to reduce movement inside the battery case. Many gel batteries also use one way valves in place of open vents.This helps the normal internal gasses to recombine back into water in the battery, reducing gassing. “Gel Cell” batteries are non-spillable even if they are broken. Gel cells must be charged at a lower voltage (C/20) than flooded or AGM to prevent excess gas from damaging the cells. Fast charging them on a conventional automotive charger may be permanently damage a Gel Battery.

In a gel battery, the electrolyte does not flow like a normal liquid. In AGM batteries all liquid electrolyte is trapped in a sponge-like matted glass fiber separator material.The “acid-starved” condition of gel and AGM batteries protects the plates during heavy deep-discharges. The gel battery is more starved, giving more protection to the plate; therefore, it is better suited for super-deep discharge applications.In high temperature condition, Gel batteries are losing less water than AGM batteries, so Gel batteries more suit high temperature application.

Wet batteries contain liquid electrolyte that can spill and cause corrosion if tipped or punctured. Therefore, they are not air transportable without special containers. They can only be installed “upright.”  AGM or Gel batteries do not have any liquid to spill, and even under severe overcharge conditions hydrogen emission is far below the 4% max specified for aircraft and enclosed spaces. The plates in AGM or Gel batteries are tightly packed and rigidly mounted, and will withstand shock and vibration better than any standard battery.

Technical Support

Sulfation is the formation or deposit of lead sulfate on the surface and in the pores of the active material of the batteries’ lead plates. Common causes of battery sulfation are standing a long time in a discharged condition, operating at excessive temperatures, and prolonged under or over chargin

The service design life of a battery varies considerably with how it is used, maintained and charged. Also temperature etc. affect battery life.

All batteries, regardless of their chemistry, self-discharge. The rate of self-discharge depends both on the type of the battery and the storage temperature the batteries are exposed to.

When charging lead acid batteries, the temperature should not exceed 120℉. At this point the battery should be taken off charge and allowed to cool before resuming the charge process.

Lead acid batteries are 100% recyclable. Lead is the most recycled metal in the world today.

The most common battery rating is the AMP-HOUR RATING. This is a unit of measurement for battery capacity, obtained by multiplying a current flow in amperes by the time in hours of discharge. (Example: A battery which delivers 5 amperes for 20 hours delivers 5 amperes times 20 hours, or 100 ampere-hours.)

Reserve capacity is the number of minutes a battery can maintain a useful voltage under a 25 ampere discharge. The higher the minute rating, the greater the battery’s ability to run lights, pumps, inverters, and electronics for a longer period before recharging is necessary. The 25 Amp. Reserve Capacity Rating is more realistic than Amp-Hour or CCA as a measurement of capacity for deep cycle service. Batteries promoted on their high Cold Cranking Ratings are easy and inexpensive to build. The market is flooded with them, however their Reserve Capacity, Cycle Life (the number of discharges and charges the battery can deliver) and Service life are poor. Reserve Capacity is difficult and costly to engineer into a battery and requires higher quality cell materials.

One cycle of a battery is a discharge from full charge to full discharge and a return to full charge again. The total number of cycles a battery can perform before failure is called its Cycle Life.

In the SERIES CONNECTION, batteries of like voltage and Amp-Hour capacity are connected to increase the Voltage of the bank. The positive terminal of the first battery is connected to the negative terminal of the second battery and so on, until the desired voltage is reached. The final Voltage is the sum of all battery voltages added together while the final Amp-Hours remains unchanged. The bank’s Voltage increases while its Amp-Hours, Cranking Performance and Reserve Capacity remain unchanged.

In the PARALLEL CONNECTION, batteries of like voltages and capacities are connected to increase the capacity of the bank. The positive terminals of all batteries are connected together, or to a common conductor, and all negative terminals are connected in the same manner. The final voltage remains unchanged while the capacity of the bank is the sum of the capacities of the individual batteries of this connection. Amp-Hours Cranking Performance and Reserve Capacity increases while Voltage does not.


Routine battery examinations divulge irregularities in the charging system as well as in the batteries. The principle method is to examine the electrochemistry of the battery through hydrometric electrolyte inspection. As previously discussed, this important examination cannot be accomplished with sealed absorption or gel batteries. Voltage readings alone require experience to interpret. Hydrometric readings will uncover early warnings of overcharging or over discharging before batteries are damaged. The state-of-charge(SOC) and reliability of a lead acid battery can best be determined by the specific gravity of the electrolyte measured directly with a common bulb-type hydrometer with a glass float. We do not recommend the ball float type hydrometer. Specific gravity is a unit of measurement for determining the sulfuric acid content of the electrolyte.

No. Sealed lead acid batteries do not require the adding of water.

Sealed lead acid battery life is determined by many factors. These include temperature, depth and rate of discharge, and the number of charges and discharges (called cycles).

A float application requires the battery to be on constant charge with an occasional discharge. Cycle applications charge and discharge the battery on a regular basis.

High heat is not good for VRLA batteries. When temperature exceeds 25℃, the battery life will be reduced in half for every 10℃ increase in the temperature. For example if the designed life of battery at 25℃ is 10 years,  the life is only 5 years when the same battery operates at 35℃.

Battery Maintenance

All lead acid batteries experience self-discharge in open circuit. The result is that the voltage and the capacity are decreased. During storage please note:

The self-discharge rate is related with the ambient temperature. The self-discharge rate is smaller when the ambient temperature is lower and grows as the ambient temperature raises.

The requirement temperature for storing NARADA batteries is from 0oC to 35oC. The storage space must be clean, ventilated and dry.An important parameter in storage is the open circuit voltage, which is related with density of the electrolyte. In order to avoid permanent damage to the plate caused by self-discharge, the batteries should be supplementary charged if they have been stored for three months. The equalization charge method should be adopted.

During storage, if the open circuit voltage drops below 2.10V/Cell, the batteries should be supplementary charged before use. The equalization charge method should be adopted.

All batteries should be fully charged before storage. It’s suggested to record the storage date in the periodic maintenance record and also the time when another necessary supplementary charge should be done.

The quality certificates of NARADA batteries record the latest charge date of the batteries. Next charge time can be calculated according to this date.

Correct charging of a VRLA battery is essential in optimizing the battery performance and life. Although a constant voltage charge should be applied, optimum charging also depends on temperature (Nominally 20-25℃), charge current (max 1/4 battery capacity) and ripple current (minimum).

A higher charging voltage is used but should NEVER be left on indefinitely since it will overcharge and destroy the battery.

For optimum performance always recharge a battery immediately after discharging.

In order to assure service life, the batteries should be correctly inspected and maintained.
The maintenance methods of Narada batteries are recommended as follows:
• Monthly Maintenance
Implement the under-mentioned inspection every month:
Keep the battery-room clean.
Measure and record the ambient temperature of the battery-room.
Check each battery for cleanness; check damage and overheating trace of the terminal, container and lid.
Measure and record the total voltage and floating current of the battery system.

• Quarterly Maintenance
Repeat monthly inspection.
Measure and record the floating voltage of every on-line battery. If more than two cellsvoltage is less than 2.18V after temperature adjustment, the batteries need to be equalization charged. If the problem still exists after adopting above-mentioned measures, the batteries need yearly maintenance or even three years’ maintenance. If all methods are ineffective, please contact us.

• Yearly Maintenance
Repeat quarterly maintenance and inspection.
Check whether connectors are loose every year.
Make a discharge test with exact load every year, discharging to 30-40% of rated capacity.

• Three-year Maintenance
Make a capacity test every three years and every year after six years of operation. If the capacity of the battery decreases to lower than 80% of rated capacity, the battery should be replaced.

OVERCHARGING is the most destructive element for battery service life. During overcharging, excessive current causes the oxides on the plates of the battery to “shed” and precipitate to the bottom of the cell. Overcharging also heats the battery, thus removing water from the electrolyte. Once removed, this material (which represents capacity) is no longer active in the battery.

If the floating voltage is not set correctly (too low or not compensated according to the temperature), the battery system will be in an insufficient charge state for a long period of time. When the electricity is out, the battery may not be able to work because the acid is satirized and the capacity is decreased.

Too low temperature will affect the capacity of a battery. While too high temperature will also cause problems, such as water loss, life decrease, thermal runaway, deformation, etc.

Not good for a battery. If a battery is put aside without charge for a long time some large size PbSO4 crystals will form on the negative plate which will affect the battery’s life and capacity.

The end voltage is also an important parameter for battery. The battery stops discharging when a certain voltage is reached. The normal safe end voltage for a battery that is discharged in 10 hours(C10) is 1.8Vpc/cell. If the end voltage is too low it will be difficult to recharge the battery again and this also decreases the charge efficiency of the battery.