1. What is a AGM (Absorbed Glass Mat )Battery?

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


2. What are the advantages of the AGM battery?

The advantages of AGM batteries are no maintenance, sealed against fumes, hydrogen, leakage, or non-spilling even if they are broken, and can survive most freezes. AGM batteries are "recombinant" ¨C 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.


3. What is a Gel Cell Battery?

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.


4. What is sulfation of batteries?

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. If the sulfation becomes excessive and forms large crystals on the plates, the battery will not operate efficiently and may not work at all. Common causes of battery sulfation are standing a long time in a discharged condition, operating at excessive temperatures, and prolonged under or over charging.


5. How long a battery can last?

The service design life of a battery are vary considerably with how it is used, how it is maintained and charged, temperature, and other factors.


6. Do batteries self-discharge when not in use?

All batteries, regardless of their chemistry, self-discharge. The rate of self-discharge depends both on the type of battery and the storage temperature the batteries are exposed to. However, for a good estimate, Narada batteries self-discharge approximately 4% per week at 80°F.


7. Is there a maximum temperature for charging lead acid batteries?

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


8. Are lead acid batteries recyclable?

Lead acid batteries are 100% recyclable. Lead is the most recycled metal in the world today. The plastic containers and covers of old batteries are neutralized, reground and used in the manufacture of new battery cases. The electrolyte can be processed for recycled waste water uses. In some cases, the electrolyte is cleaned and reprocessed and sold as battery grade electrolyte. In other instances, the sulfate content is removed as Ammonia Sulfate and used in fertilizers. The separators are often used as a fuel source for the recycling process.


9. What is battery rating?

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.)

Manufacturers use different discharge periods to yield an different Amp-Hr. Rating for the same capacity batteries, therefore, the Amp-Hr. Rating has little significance unless qualified by the number of hours the battery is discharged. For this reason Amp-Hour Ratings are only a general method of evaluating a battery's capacity for selection purposes. The quality of internal components and technical construction within the battery will generate different desired characteristics without effecting its Amp-Hour Rating. For instance, there are 150 Amp-Hour batteries that will not support an electrical load overnight and if called upon to do so repetitively, will fail early in their life. Conversely, there are 150 Amp-Hour batteries that will operate an electrical load for several days before needing recharging and will do so for years. The following ratings must be examined in order to evaluate and select the proper battery for a specific application: COLD CRANKING AMPERAGE and RESERVE CAPACITY are ratings used by the industry to simplify battery selection.


10. What does the Reserve Capacity rating mean and how does it apply to deep cycle batteries?

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.


11. What is battery cycle life?

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. Moat battery manufacturers will not discus the Cycle Life of their product. Many advertised Deep Cycle batteries have not been tested, or, which is the case with cranking batteries, were never designed for long Cycle Life .


12. What is the difference between series battery connections and parallel battery connections and how do they increase battery capacity and voltage?

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.


13. Does overcharging damage batteries?

OVERCHARGING is the most destructive element in battery service. Usually the boater is not aware that this is occurring as he believes his alternator or battery charger is "automatic." Unfortunately, these automatic circuits are sensitive to voltage surges, heat, direct lightening strikes and indirect lightening electromagnetic influences and could fail or shift their calibration. When they fail, overcharging begins to effect the batteries. During overcharging, excessive current causes the oxides on the plates of the battery to "shed" and precipitate to the bottom of the cell and also heat the battery, thus removing water from the electrolyte. Once removed, this material (which represents capacity) is no longer active in the battery. In addition, the loss of water from the electrolyte may expose portions of the plates and cause the exposed areas to oxidize and become inactive, thus reducing additional capacity. Sealed batteries are not immune from the same internal results when overcharged. In fact, sealed recombination absorption and gel batteries are particularly sensitive to overcharging. Once moisture is removed from the battery, it cannot be replaced. Portions of the battery damaged due to overcharging are irretrievable. However, if detected early, corrective adjustments to the charging device will save the undamaged portion of the battery. Initial signs of overcharging are excessive usage of water in the battery, continuously warm batteries, or higher than normal battery voltages while under the influence of the charger. If overcharging is suspected, correct immediately.


14. FAQ header 3Does overdischarging damage batteries?

OVERDISCHARGING is a problem which originates from insufficient battery capacity causing the batteries to be overworked. Discharges deeper than 50% (in reality well below 12.0 Volts or 1.200 Specific Gravity) significantly shorten the Cycle Life of a battery without increasing the usable depth of cycle. Infrequent or inadequate complete recharging can also cause overdischarging symptoms called SULFATION. Despite that charging equipment is regulating back properly, overdischarging symptoms are displayed as loss of battery capacity and lower than normal specific gravity. Sulfation occurs when sulfur from the electrolyte combines with the lead on the plates and forms lead-sulfate. Once this condition becomes chronic, marine battery chargers will not remove the hardened sulfate. Sulfation can usually be removed by a proper desulfation or equalization charge with external manual battery chargers. To accomplish this task, the flooded plate batteries must be charged at 6 to 10 amps. at 2.4 to 2.5 volts per cell until all cells are gassing freely and their specific gravity returns to their full charge concentration. Sealed AGM batteries should be brought to 2.35 volts per cell and then discharged to 1.75 volts per cell and their this process must be repeated until the capacity returns to the battery. Gel batteries may not recover. In most cases, the battery may be returned to complete its service life.

CHARGING Alternators and float battery chargers including regulated photo voltaic chargers have automatic controls which taper the charge rate as the batteries come up in charge. It should be noted that a decrease to a few amperes while charging does not mean that the batteries have been fully charged. Battery chargers are of three types. There is the manual type, the trickle type, and the automatic switcher type.


15. How can I evaluate the health and charge state of a battery?

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 overdischarging before batteries are damaged. The state-of-charge 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. The recommended fully charged specific gravity of marine batteries is 1.255 to 1.265 taken at 80°C More than .025 spread in readings between fully charged cells indicates that the battery may need an equalization charge. If this condition persists, the cell is failing and the battery should be replaced. Since water has a value of 1.000, electrolyte with a specific gravity of 1.260 means it is 1.260 times heavier than pure water while pure concentrated sulfuric acid has a specific gravity of 1.835.


16. Do I need to add water to my battery?

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


17. What determines the life of an VRLA battery?

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).


18. What is the difference between float and cycle applications.?

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.


19. What is the difference between VRLA (Gel or AGM) batteries and traditional wet or flooded batteries?

Wet batteries do not have special pressurized sealing vents, as they do not work on the recombination principle. They contain liquid electrolyte that can spill and cause corrosion if tipped or punctured. Therefore, they are not air transportable without special containers. They cannot be shipped via Express Courier or Parcel Post or used near sensitive electronic equipment. They can only be installed "upright." Because of the cost in time (man-hours), products (distilled water etc), damaged clothing, and polluted environments when being charged and/or discharged wet batteries may actually end up costing more money over the life of the battery than do high quality VRLA batteries. Some brands of wet or flooded batteries are also marketed and sold as sealed or maintenance free, but they are still flooded cell batteries ----not "acid-starved" ----and they DO NOT have the same pressurized venting system.

Wet batteries more easily to lose capacity and become permanently damaged. AGM or Gel batteries have a very low self-discharge - from 1% to 3% per month is usual. This means that they can sit in storage for much longer periods without charging than standard batteries. Narada VRLA batteries remaining capacity above 94% after storage 3 months at 20 degree Celsius.

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.


20. What are the differences between gel batteries and absorbed glass mat (AGM) batteries?

Both are recombinant batteries. Both are sealed and valve-regulated and are considered non-spill able and both are considered "acid-starved." 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.


21. What is the shelf life of a VRLA 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°C. 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.


22. How to charge your battery?

Correct charging of a VRLA battery is essential in optimising battery performance and life. Although a constant voltage charge should be applied, optimum charging also depends on temperature (Nominally 20°C), charge current (max 1/4 battery capacity) and ripple current (minimum). Two basic categories of charging exist.

This charging method is used in applications such as emergency back-up when the battery is required only upon mains failure e.g., Alarm Panels, Emergency Lighting, UPS. In each case the battery is continuously on charge and consequently the recommended voltages are slightly lower than cyclic charging so as not to damage the battery.

Cyclic charging is used in applications where the battery is repeatedly discharged then charged, e.g. Portable equipment, Wheel Chairs, Golf trolleys etc.

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.


23. How to store and maintenance your battery?

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

The self-discharge rate is related with ambient temperature. The self-discharge degree is smaller when the ambient temperature is lower, otherwise is larger. The requirement temperature of NARADA batteriesĄŻs storage environment is from 0°C to 35°C. The storage place must be clean, ventilated and dry.An important parameter in storage is 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 is lower than 2.10V/Cell, the batteries should be supplementary charged before use. The equalization charge method should be adopted. All batteries, which are ready to store, should be fully charged before storage. ItĄŻs suggested record the storage time in the periodic maintenance record and record the time when another necessary supplementary charge should be made.The quality certificates of NARADA batteries record the latest charge time of the batteries, next charge time can be calculated according to this charge time.

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 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 floating voltage of every on-line battery. If more than two cells voltage 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 yearsĄŻ maintenance. If all methods are ineffective, please contact us.

Yearly Maintenance

  • Repeat quarterly maintenance and inspection.
  • Check whether connectors are loose or not every year.
  • Make a discharge test to check with exact load every year, discharging 30-40% of rated capacity.

Three-year Maintenance

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


24. What is the relationship between ambient temperature Vs. Battery Life?

The heat disseminates performance of VRLA battery is bad, it is liable to cause heat run away when heat accumulates. When temperature exceeds 25°C, the battery life will decrease half per 10°C temperature raise.
t25=tT x 2(T­25)/10
Notes tT the actual ambient temperature;
tT is designed life at T ambient temperature
t25 is designed life at 25°C ambient temperature
Above-mentioned formula can be used during 10°C-40°C
For example, the designed life of battery at 25°C is 10 years, when battery operates at 35 10°C, the actual life is only 5 years.