Frequently Asked Questions (FAQs)

Frequently Asked Questions (FAQs)

Gel battery is a VRLA (valve regulated lead acid battery)battery with a jellified electrolyte; the sulfuric acid is mixed with fumed silica, which makes the resulting mass gel-like and immobile. Following are the basic features of gel batteries.
  1. It is sealed using special pressure valves and should never be opened
  2. Typically uses Calcium/Calcium metal alloys
  3. It is maintenance-free with proper charge controls
  4. Uses a recombination reaction to prevent the escape of hydrogen and oxygen gases normally lost in a flooded lead-acid battery (particularly in deep cycle applications)
An AGM battery is a valve regulated lead acid battery. It uses glass mate as separator which absorb all the mobile electrolyte and makes it static which will reduce the water loss.
  1. It is sealed using special pressure valves and should never be opened
  2. Typically uses Calcium/Calcium metal alloys.
  3. With proper charge controls is maintenance-free
  4. Has its entire electrolyte absorbed in separators consisting of a sponge-like mass of matted glass fibers
  5. Uses a recombination reaction to prevent the escape of  hydrogen and oxygen gases normally lost in a flooded lead-acid battery

A Flooded battery is a type of lead acid battery in which the electrolyte is in movable liquid state

  1. Can be both sealed and open-vented
  2. Can use High Antimony, Low Antimony or Calcium metal alloys or a combination of Calcium and Low Antimony grids (hybrid)
  3. Requires maintenance in cyclic applications
  4. Its entire electrolyte volume is free to move within the cell with nothing to prevent the escape of hydrogen and oxygen gases normally lost during charging and discharging (particularly in deep cycle applications)
Both Gel and AGM batteries are recombinant batteries. Both are sealed and valve regulated and are considered non-spillable and both are considered “acid-starved.” In an AGM or 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. In a Gel battery the electrolyte is mixed with fumed Silica which changes it into a gelled consistency.
  1. Wet or flooded batteries do not have special pressurized sealing vents, as they do not work on the recombination principle
  2. Wet batteries contain excess liquid electrolyte that can spill and cause corrosion if tipped or punctured
  3. Wet batteries should not be used near sensitive electronic equipment
  4. Wet batteries can only be installed “upright”.
A key feature of VRLA-batteries is the process of recombination of oxygen during the charge process. The cycle starts at the positive plate. Water is broken down and gaseous oxygen is formed. The hydrogen ions remain dissolved in the electrolyte and are not released as gas, which is the case with vented wet type batteries. The electrons move away via the positive plate.
What happens now to the oxygen as it makes its way to the negative plate is different in wet vented batteries than it is in VRLA batteries.

In wet or flooded lead-acid batteries of the vented design with excess electrolyte, it is practically impossible for the oxygen to move to the negative plate. Immediately after having left the positive plate, it bubbles up and escapes through the vent plug.

In VRLA batteries, a densely porous medium is offered to the oxygen to facilitate its movement. The porous medium in an AGM VRLA battery is the glass mat. The porous medium in a Gel VRLA battery is the cracks in the gelled electrolyte.

Figure 1 - Vented Battery Gassing and VRLA Battery Recombination

VRLA batteries are designed using proven gas recombination technology which removes the need for regular water addition by controlling the evolution of hydrogen and oxygen during charging. This means that the oxygen normally produced on the positive plates of all lead-acid batteries is absorbed by the negative plate through a porous medium (see Figure 1) without being vented. This suppresses the production of hydrogen at the negative plate. Water (H20) is produced instead, retaining the moisture within the battery. It never needs watering and should never be opened as this would “poison” the battery with additional oxygen from the air.

The retained oxygen produces an over-pressure within the cell. This is normal. The battery’s sealing valves should not open at too low pressure because this would allow too much oxygen to escape and be irretrievably lost. If the defined opening pressure is achieved, the sealing valve will open for a short time to release over-pressure caused by the accumulated gas. Under normal operating conditions this gas consists mainly of hydrogen. Under unfavorable conditions, (high charge voltages at high temperatures, for instance) oxygen would also escape.

Different types of batteries use test procedures that allow different end of life criteria. For example:

  1. An electric vehicle or standard deep cycle product would be considered to be at its end of life when it was not able to deliver 50% of its rated capacity
  2. For home UPS/ Inverter
  3. An electric vehicle or standard deep cycle product would be considered to be at its end of life when it was not able to deliver 60% of its rated capacity when discharged at 3 Hours Rate

How long a battery will last in terms of its usable life depends completely on how often the battery is discharged and charged, how fast or at what rate it is discharged and charge, to what extent it is discharged or the depth of discharge, and how well or properly it is recharged. Surrounding temperature of the batteries also impact the life of the battery. Higher temperature increases the performance of the battery but lowers the life cycle of the battery.

You should replace the battery if one or more of the following conditions occur:
  1. If there is a 0.030 (30 “points”) or more difference in the specific gravity reading between the highest and lowest cells of a flooded battery. This means the flooded battery you are testing has a weak or dead cell(s)
  2. If battery is heating too much on uses
  3. If after full Charging battery Gravity is not maintained, and difference is more in each cell if electrolyte spillage & more water top-up is not happened
  4. If the battery will not recharge to a 75% or more state-of-charge level
  5. If a digital voltmeter indicates 0 volts on a battery, you know to have been charged properly, you have an open or short-circuited cell and you should replace the battery
  6. If a digital voltmeter indicates < 10.5 V volts on a battery you know to be a fully charged battery, then the battery probably has a shorted or dead cell
  7. If the battery is fully charged, check the float indicator showing green or a good voltmeter indication then you can test the capacity of the battery by applying a known load and measuring the time it takes to discharge the battery until 20% of its originally published capacity is remaining
Battery capacity
maximum discharge capacity @ 80% discharge
Charging option
Only Grid charging 
Solar + Grid Charging 
Only Solar
By default Inverter charging current set at 15A-16A, so in 10-11 Hrs battery will be fully charged. 10 Hrs (If Grid power avilable on day time average 10 Hrs so minimum solar wattage=1.5* Battery Capacity) Total Solar Panel Capacity= 3 time of Battery Capacity
1) Battery charge by solar power and load run by grid. Ex- 200Ah Battery charging need solar  panel capacity= 3*200= 600 Watt.
2) If solar is unsuffceint ,so Battery will charge by Solar+Grid charging Ex- 100 W Solar Panel generate power = 100/17.5*80% = 4.5 AMP/ hour. Average Sun power is 6 Hrs , so 600 watt panel generate = 6*4.5*6 Total power is 162 Amp.
3) Charging current is sharing basis, battery is charged 1st by Solar. If solar current is going down in morning & evening time then balance power will be taken by Grid.

Bulging is when battery sides take curvy shape(outside) due to non-passage of gases. Bulging (gas formation) happens due to the following reasons:

  1. Expansion of plates during charging and discharging process
  2. Over charging of battery
  3. Chocking of vent plugs thus blocking release of gas
  4. Impurities in alloy

Eastman TTMF & STMF battery do not bulge because:

We use of high-quality alloy resulting is very less gas formation.
We use specially design aqua trap vent plugs resulting is smooth release of gas.

Eastman T-Gel Batteries do not bulge because:

The electrolyte is “condense form of fumed silica gel” resulting in negligible gas formation.
Even for the negligible amount of gas to escape, air vents are placed which opens when a certain amount of gas pressure is produced in the battery.
The container is heavily reinforced (rib design) which gives it anti-bulge properties.

The charging pattern of Eastman Tubular Gel battery and SMF battery is same. But the upper charging cut off voltage is different.

For tubular battery the upper charging cut off voltage is 14.4V and for the SMF battery it is 14.0/14.2 Volt.

Due to this reason inverter manufacturer give option in inverters to charge the battery in SMF or Tubular mode.

Eastman batteries are to be charged in Tubular mode.

Measurement and troubleshoot


A solution of baking soda and water. Use 1 cup of baking soda for every gallon of water.
The limiting factor of battery’s shelf life is the rate of self-discharge which itself is temperature dependent. VRLA batteries will self-discharge less than 3% per month at 77º F (25º C). Flooded batteries will self-discharge up to 4% per month at 77º F (25º C). VRLA batteries should not be stored for more than 6 months at 77º F (25º C) without recharged. The specific gravity or voltage of flooded batteries should be monitored every 4 – 6 weeks and should be given a boost charge when they are at 70% state of charge (SOC). When batteries are taken out of long storage, it is recommended to recharge before use
The specific gravities of batteries are an excellent tool to determine the state of charge of batteries and their ability to accept a charge. Unfortunately, the specific gravities can also lead to an erroneous conclusion if we do not specify the conditions under which the measurements were taken. The two major sources of error in measuring specific gravities are lack of temperature compensation and water addition. Since the specific gravities of batteries are affected by temperature, the measurements must be temperature compensated. The best way to compensate for cold temperatures is to subtract 5 points from your reading for every 1 º C below 80º F (27º C). To compensate for hot temperatures simply add 7 points from your reading for every 1º C degrees above 80º F (27º C). Also, the addition of water should only be done once the batteries are fully charged as the electrolyte levels vary as a function of state of charge and are highest once the batteries are fully charged. Please use distilled water only and note that adding water will lower the specific gravities of your batteries. The specific gravities cannot be used as a reliable source unless we account for the two sources of error mentioned above.
It is completely normal for flooded batteries to lose water. They lose water because of the gassing that they go through with every charge. Gassing is an important part of the recharge process. The gassing allows the electrolyte to mix well and helps the battery get back to a fully charged state at the end of the charge process. Unfortunately, the gassing also causes water to be lost. The addition of water should be only be done once the batteries are fully charged as the electrolyte levels vary as a function of state of charge and are highest once the batteries are fully charged. The correct electrolyte level is check with level indicators provided with batteries. Please use distilled water only.
Water is lost during the charging of flooded batteries. The best time to water your batteries is always at the end of the charge cycle. If your indicator level is at red level needs to indicate that you need to add water.
It is best to check your new batteries regularly as this will give you a good feel for how often your application will require battery watering. WARNING: A brand new battery may have a low electrolyte level. Charge the battery first and then add water if needed. Adding water to a battery before charging may result in overflow of the electrolyte
Yes, de-ionized water can be used instead of distilled water. However, distilled water is preferred because although de-ionized water has all free ions removed, distilled water may still contain some minerals that may be harmful to the battery. In addition, distilled water is generally more available than de-ionized water.
In flooded batteries we often to provide level indicator for all cells. You need to check the marks which areindicated over level indicator. So always electrolyte level will be always same & you can fill water until level will reach upto green level marked on level indicator.
Terminal Type Torque (N.m)
L- Type 8-10 N.m
WARNING: Do not over tighten terminals. Doing so can result in post breakage, post meltdown, and fire.
The only way that a battery can freeze is if it is left in a state of partial or complete discharge. As the state of charge in a battery decreases, the electrolyte becomes more like water and the freezing temperature increases. The freezing temperature of the electrolyte in a fully charged battery is -92º F (-69º C). At a 40% state of charge, electrolyte will freeze if the temperature reaches approximately 16º F (-9º C).
Our batteries have life expectancy of the life expectancy of batteries in very dynamic and depends on a number of application specific variables. The life expectancy depends on the proper sizing of the battery bank, depth of discharge, type of loads, battery maintenance regime, ambient temperature, and charging algorithm.
Lead and Acid are more hazardous to the environment, so placing a battery in a remote area is more important. Avoid locations where freezing temperature are expected and High state of charge prevents freezing. Avoid high-temperature places, that will increase the self-discharge of the battery. Completely charge the battery and store the battery in proper ventilated area & ambient temperature conditions.


The 100-hour rate is just an index that is used in the battery industry to compare batteries of different types and sizes. The 100-hour rate is the number of Ahs the battery will deliver during a 100-hour discharge. The capacity of a battery, in Ahs, is a dynamic number that is dependent on the discharge current. For example, a battery that is discharged at 10A will give you more capacity than a battery that is discharged at 100A. With the 100-hr rate, the battery is able to deliver more Ahs than with the 20-hr rate because the 100-hr rate uses a much lower discharge current than the 20-hr rate. Both rates are used as baselines in different parts of the world. Either rate, however, will give you the same view of a battery. A higher capacity battery will have higher 5- and 20-hour rates than a battery with lower capacity.
It represents the discharge rate of battery for 20 hours. For example:
      A 150 AH battery at C20, will last for 20 hours on a load of 7.5 A.
      A 150 AH battery at C10 will last for 10 hours on a load of 15 A.
      A 150 AH battery at C5 will last for 5 hours at a load of 30 A.


Equalizing is the process of overcharging the battery that helps to prevent the stratification. This means the concentration of acid will be higher at the bottom of the battery than that of top. To overcome that equalization is required.
Equalizing should be performed when a battery is first purchased (called a freshening charge) and on a regular basis as needed. How often this might occur with your battery will vary depending on your application. You will need to monitor your battery voltage and specific gravity to determine when equalization is needed. For example, it is time to equalize if the measured specific gravity values are below manufacturer’s recommended values after charging (recommended value for EastmanTubular batteries is 1.260 +/- .007 at 80º F (27º C)). Equalizing is also required if the specific gravity value of any individual cell varies 30 points or more. In addition, reduced performance can also be an indicator that equalizing is necessary. Equalization should be performed when individual battery voltages in a battery pack range greater than 0.30 volts for 12-volt batteries.
Lead acid batteries do not develop any type of memory. This means that you do not have to deep discharge or completely discharge a battery before recharging it. For optimum life and performance, we generally recommend a discharge of 20 to 50% of the batteries rated capacity even though the battery is capable of being cycled to 80%.
Charging voltage - 14.4V and charging current is 10% of its capacity.Avoid overcharging of battery, overcharging leads to gas evolution. Use the recommended charger only or charging setting as EAPL suggested.

Date Coding

Seventeen-digit codes indicate the packing of battery.
xxxCH9xxxxxxxxxxx – 12/08/2019
4th character – Date (1,2,3…9, A, B, C…).
5th character - Month(A-Jan, B-Feb, L-Dec).
6thCharacter – Year (7- 2017, 8- 2018, …., 6- 2026).

Additives and external compositions

We don’t recommend that you add anything to your batteries other than distilled water. Extensive testing has shown that most of these additives do not work as advertised; in fact, some may do more harm than good. Be aware that adding anything other than water to your batteries will void the warranty.
We don’t recommend the use of desulfators or any other external device, as they tend to do more harm than good. No external device or chemicals need to be added to our products – only distilled water
Under normal operating conditions, you never need to add acid. Only distilled, deionized or approved water should be added to achieve the recommended levels mentioned above.

Battery Selection

Proper battery selection may require the assistance of a knowledgeable battery sales/service technician.
  • For long life inverter/ups application flooded tubular batteries are recommended.
  • For high current discharge flat plate batteries are preferred.
A deep cycle battery has the ability to be deeply discharged and charged many times during its service life. It is designed specifically for powering electrical equipment for long periods of time. An automotive or starting battery is designed for brief bursts of high current and cannot withstand more than a few deep discharges before failure. This is why it is unable to start your car if you accidentally leave the lights on more than a couple of times. For applications where both engine starting and light deep cycling are required, a dual-purpose battery is often used. This type of battery is neither a starting nor a deep cycle battery but rather a compromise between the two, so it performs both functions adequately. Only deep cycle batteries should be used in renewable energy applications.
Systems with loads greater than 100 watts continuous will be better served by higher voltages such as 24 and 48 volts due to the reduced size of wiring required to minimize voltage drop which impacts overall system cost and ease of installation.
The composition of the plate grid alloy can have a major effect on operating characteristics, such as behavior on float charging and cycle life. Older lead-antimony designs have good cycling capability but require frequent water additions, particularly towards the end of life, due to antimony migration between the plates. Cells with lead-calcium alloys require far less watering but tend to have a poor cycle life. Lead-selenium alloys are actually low-antimony types with the addition of selenium as a hardening agent. Such alloys promote good cycling capability, while maintaining a constant and fairly low level of water consumption. Many variants on these alloy types are commercially available.

Common Mistakes

Undercharging: Continually operating the battery in a partial state of charge or storing the battery in a discharged state results in the formation of lead sulfate compounds on the plates. This condition is known as sulfation. Both of these conditions reduce the battery’s performance and may cause premature battery failure. Undercharging will also cause stratification.
  • Overcharging: Continuous charging causes accelerated corrosion of the positive plates, excessive water consumption, and in some cases, damaging temperatures within a lead acid battery.
  • Under watering: In flooded batteries water is lost during the charging process. If the electrolyte level drops below the tops of the plates, irreparable damage may occur. Water levels should be checked and maintained routinely.
  • Over-watering: Excessive watering of a battery results in additional dilution of the electrolyte, resulting in reduced battery performance. Additionally, watering the battery before charging may result in electrolyte overflow and unnecessary additional maintenance.
  • DM water: It is recommended to use only demineralized or distilled water, Normal tap water should not use for battery, it will reduce the life of the battery.

Temperature Factor and Effects

At higher temperatures (above 80º F (27º C)) battery capacity generally increases, usually at the cost of battery life. Higher temperatures also increase the self-discharge characteristic. Colder temperatures (below 80º F (27º C)) will lower battery capacity and prolong battery life. Cooler temperatures will slow self-discharge. Therefore, operating batteries at temperatures at or slightly below 80º F (27º C) will optimize both performance and life.

Battery Recycling

Lead acid batteries are 97% 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 wastewater 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.
Old batteries may be returned to the battery retailer, automotive service station, a battery manufacturer or other authorized collection centers for recycling. If you are not sure where to take your spent batteries, call your local Eastman dealer for assistance.
Battery capacity is basically a linear relationship. A good rule of thumb is that for every 15º F (9º C) above 80º F (27º C), capacity is increased by 10% and for every 15º F (9º C) below 80º F (27º C), capacity is reduced by 10%.
Temperature will affect specific gravity readings. As temperature increases, the electrolyte solution expands and as temperature decreases the electrolyte solution contracts. As a result, it is a good practice to temperature correct specific gravity readings. Here are the relationships Eastman recommends using:
      Every 1degree above 27º C add 7 points to the hydrometer reading.
      Example: @ 32º C the hydrometer reads: 1.225 the actual reading: 1.225+ 0.0035 1.2285.
      For every ten degrees below 27º C subtract 7 points from the hydrometer reading.
Example: @ 22º C the hydrometer reads: 1.225 the actual reading: 1.250 – .003 = 1.247.
Temperature will affect voltage readings. As temperature increases, voltage decreases. Conversely, as temperature decreases, voltage increases. Here are the relationships:
Eastman recommends using the following:
      For every 1 C below 25º C add 0.005 volts per cell to the charger voltage setting.
      2: A 12-volt battery @ 21º C. The recommended charging voltage at 25º C is 14.8 volts. The adjusted charging voltage is 14.8 + (6 cells * 4 degrees below * 0.005) = 14.92 volts.
    For every 1º C above 25º C subtract 0.005 volts per cell to the charger voltage setting.
      2: A 12-volt battery @ 29.5º C. The recommended charger voltage at 25º C is 14.8 volts. The adjusted charging voltage is 14.8 – (6 cells * 4.5 degrees above * 0.005) = 14.67 volts.
When charging lead acid batteries, the temperature should not exceed 55ºC. At this point the battery should be disconnected from all charging sources and loads in order to cool before resuming the charge process.
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