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EnerSys is a US MNC, and the largest in the world for Industrial batteries
It has presence in more than 100 countries with manufacturing facilities in 32 of them
In India, it has its HQ in Hyderabad, with the factory in Vijayawada, however, all the batteries for UPS and Hospital applications are imported either from France, Poland, US, etc
It has a pan India service network
It also provides buy-back option for the old batteries

EnerSys Reserve Power batteries

The VRLA technology, used by all the local battery manufacturers, was invented by M/s Gates Energy, which later became part of EnerSys®.
EnerSys® has then built upon this VRLA technology, and dramatically enhanced it, to create its TPPL technology.
TPPL batteries outperform the competition in all parameters…
Superior Performance– The extremely thin plates enable much more plates to be packed into each cell, thereby providing much higher surface area for reaction. The high purity of the raw materials used (99.99% pure lead / Medical grade acid, Brass inserts with-in the terminals, etc.) leads to much lower resistance and extremely low self-discharge rates.
Higher Shelf life – It can be kept idle for more than 2 years, while the competition batteries cannot be kept for more than 2 or 3 months.
Higher Service life – It boasts of unmatched and unparalleled designed life of 15 years.
Minimal gas generation – Due to the purity of the components that are used, the gas generation is negligible compared to the competition. This reduction in gas generation has the benefit of providing reduced operating temperatures, reduced float currents, and reduced positive grid corrosion and all these contribute to increase in service life.
Better recombination efficiency – The efficiency of the recombination is much higher and as a result, whatever little is generated is also mostly converted back into the solution.
Minimal gas emission (extremely low hydrogen evolution) – Due to the purity of the lead, the generation is low, and due to use of automated plants and robotics a very high level of process control is ensured, which in turn leads to very high oxygen recombination efficiency.
Low Self-discharge Rates – this is what contributes to the high shelf life and is as a result of the purity of lead.
Much higher power density – Due to the use of very thin plates, more plates are packed into the same area, thus ensuring availability of much higher surface area for the reaction.
Rapid Recharge Capability - TPPL offers the opportunity to reduce the recharge time of the UPS battery after a discharge event.
Reduced temperature management in battery rooms - They have much reduced requirements for temperature control in the battery room.
Reduced energy costs by reducing air conditioning load.
Exceptional cyclic performance in both float and fast charge applications, even in the hottest and the harshest operating environments
Exceptional fast charge acceptance ability
Resilient to harsh environments
Availability of pan India Service network – these are extremely reliable and rugged batteries, however, EnerSys has a pan India service network to attend to any eventuality.
Lowest Cost of Ownership– the far greater life offered reduces the total cost of ownership. In fact, when compared to local brands, the cost of ownership could be anywhere between 25% to 60% lower!!!

As an example - a large Indian battery company gives 2 years warranty on one of its popular models and it costs Rs.16,000, while a battery from EnerSys for the same application would cost Rs.25,000 but comes with a 5 year warranty - extrapolated this would work out to a saving of 60%.

TPPL technology involves the use of electrodes that are of high purity and thin compared to more conventional technologies. In order to understand the critical nature of lead purity in TPPL products, it is important to understand some key failure modes and performance characteristics associated with lead acid batteries, and subsequently how lead purity and plate thickness affect them.

Extended High Rate Run Times and Long Life

The positive grid of a lead acid battery is the lead framework, which supports the Positive Active Material (PAM) of the battery. Together, the grid and PAM form an electrode, which is often referred to as a plate. The grid provides a physical structure for the PAM to cling against so that the PAM is held together. Additionally, the grid is an electrical conductor which allows current flow, which originates from reactions in the active material, through the plates and out of the plates.

However, over the life of the battery, the lead in the grid tends to corrode. This corrosion is the process of metallic lead converting to lead oxide. Positive grid corrosion is always present in a lead acid battery because the positive grid is operating in a sulfuric acid environment at a voltage where it is thermodynamically favored to oxidize. As this corrosion occurs, it is ultimately destructive to the battery in two ways. First, as the grid corrodes, it loses conductivity so that it is less effective at allowing the current to flow. Second, since the corrosion product, an oxide of lead, is less dense than the original metallic lead, the grid volume will increase, and the grid will begin to grow. As lead along the surface of the grid, and in the grain boundaries of the lead, are converted to lead oxides, stress is created on the remaining metallic lead, stretching it and making it even more subject to corrosion. This growth can cause the PAM to lose electrical contact with the grid. Both grid corrosion and grid growth reduce the conductivity and performance of the battery, and eventually the battery will fail.

This grid corrosion occurs in all lead acid batteries, but the rate at which it occurs is controlled by a number of factors, some of which relate to the application, such as float voltage and temperature. However, an extremely important factor controlling the rate of grid corrosion is the purity of the lead. High purity lead has a lower corrosion rate than lead with alloys, especially alloys such as calcium or antimony which are often used in battery grids. Not only is the corrosion rate higher for lead calcium alloys, but the corrosion tends to follow the calcium rich grain boundaries which means that corrosion can relatively quickly extend through the thickness of the grid resulting in loss of grid integrity. TPPL technology, with high purity lead, greatly delays these issues. Figure 2 shows a comparison of pure lead and lead calcium positive grids after life testing. Note that there is some loss of metallic lead from the TPPL grid, but it is homogenous along the surface and minimal in depth. The calcium grid shows a complete loss of integrity, reflecting both the increased rate of corrosion and the fact that the corrosion has effectively cut the grid into small pieces via the corrosion along grain boundaries. Figure 3 shows life projections, based on elevated temperature testing, for DataSafe^® XE batteries at 25°C and at30°C.

Other lead acid battery designs utilizing alloys such as calcium tend to use thicker grids, effectively carrying extra lead thickness as sacrificial material to extend the battery life as the corrosion eats the grid away.

Alternatively, they may use thin grids and accept the reduction in battery life that is inherent to the alloyed grid. The practice of using thicker grids to extend the life of alloyed grids can be effective when proper care is taken to manage grain.

boundaries, but results in a thicker plate. The downside is

Figure 3: DataSafe^® XE Battery Life Projections at 25°C and 30°C

that thicker plates do not discharge as efficiently as thinner ones because the active material at the center of the plates has limited access to electrolyte. With the non-alloyed TPPL design, the use of thinner electrodes means that more electrodes can be used within the cell. More electrodes equal more electrode surface area, or specifically, more REACTIVE electrode surface area.

Higher reactive surface area, like thinner active material, results in better active material utilization. As the discharge rate increases, the effectiveness of a thick electrode at utilizing the active material at the center of the plate drops to lower and lower levels. To the UPS engineer, this means that with thin plate batteries, smaller batteries can be used to achieve the same run times, and as discharge rates increase the TPPL advantage grows. Figure 4 shows a comparison of the DataSafe^® XE battery series to conventional lead calcium AGM batteries. This example shows a 50% increase in power density, which could allow for a 30% plus reduction in battery weight, a similar reduction in volume.

Figure 4: Comparison of Power Density during Short Discharges

The bottom line is that TPPL products are able to use thinner grids without sacrificing battery life due to the fact that corrosion rates are reduced. This results in thinner electrodes and thus higher capacity, especially during high-rate discharges. Put more simply, the use of thinner plates means more plates can be used so that there is greater reactive plate surface area. This gives the user increased power and energy from the battery without giving up battery life.

Rapid Recharge Capability

The same factors that control active material utilization efficiency during discharge come into play during recharge. Recharge rates are limited by the reactive surface area and rate at which acid can diffuse to and from the most difficult to reach active material at the center of the plate. As electrodes become thinner, the distance that electrolyte has to diffuse becomes shorter. If adequate recharge current is available, TPPL offers the opportunity to reduce the recharge time of the UPS battery after a discharge event.

Lead calcium grid batteries generally require that the recharge current be limited to 0.4C (40amps for a 100 Ahr battery) or less. Thus, from a full discharge after a 1-hour charge, the battery will have achieved at most a 40% State of Charge (SOC). Beyond that point, the amount of current the battery will accept will diminish so that the rate of recharge drops even further. A lead calcium grid battery would require 5 to 10 hours, or longer, before reaching a full SOC after a full discharge.

With TPPL, the situation is significantly different. The DataSafe^® XE battery series do not require a limit to the current, which can be made available to the battery as long as the charge voltage is properly regulated. As an example, the TPPL battery will readily accept 1C (100A for a 100Ahr battery) until it approaches 85% SOC while maintaining a very high level of energy efficiency.

That means that the battery can achieve 85% SOC in around 51 minutes following a full depth of discharge. Beyond that point, the current will diminish, but 100% SOC can still be achieved in less than 2.5 hours. Under the more typical condition of less than full discharges, recharge times will be shorter. Figure 5 shows the relationship between available current to charge the DataSafe^® XE battery series products and the time to recharge to 100% SOC, as a function of depth of discharge.

Figure 4: Comparison of Power Density during Short Discharges

Low Gas Generation and Emission

Lead acid batteries use an electrolyte, which is a mixture of water and sulfuric acid. In the

battery’s internal environment, the water is thermodynamically favored to decompose to oxygen and hydrogen. This oxygen and hydrogen from decomposition will either exit the battery causing dry out (a failure mode) or react with other materials in the cell. If the reaction is with the grid, the result is grid corrosion and shortened life. If the reaction is with the active material, the result is self-discharge of the battery. However, even though decomposition of water is thermodynamically favored inside a lead acid battery, the rate (kinetics) is heavily influenced by other factors.

Electrolysis tends to require a metallic surface which serves as a catalyst. On a pure lead surface, electrolysis tends to occur very slowly. Metallic impurities, however, tend to provide a surface which promotes electrolysis. The suppression of electrolysis on the high purity lead surface of TPPL greatly reduces the rate of gas generation. This reduces the rate of battery dry out, and it also reduces the amount of potentially explosive gas which can exit the battery.

There are two additional key points associated with this topic which may not be obvious but are critical to TPPL technology. The first relates to the purity of ALL of the materials used in cell manufacturing. Unlike grid corrosion, which is most directly impacted by alloys only in the grid metal, gas generation is dependent on the purity of all of the materials inside the cell, including the electrolyte and anything which comes in contact with the electrolyte. In addition to the grid, potential sources of impurities in the cell are : the lead oxides used to manufacture the active materials; the acid and water used to produce the electrolyte; and the glass mat that absorbs the electrolyte. In the manufacture of TPPL products, EnerSys^® has established the highest levels of purity for all of these materials, and vigorously tests those materials to assure that gassing rates are at industry leading low levels.

The second point is that a key difference between TPPL and other AGM designs is the level of gas GENERATION, not to be confused with gas emission. Many AGM designs have advanced to the point where oxygen recombination efficiency is high. This means that gas emission, or the amount of gas which exits the cell, is relatively small. However, that does not necessarily infer that the amount of gas being generated within the cell is low. It only means that the cell is very good at preventing the gas from leaving the cell.

Why does this matter? To find the answer, we need to look at what happens to the gas in the cell. As previously noted, if it stays in the cell it will basically be consumed in one of two reactions.

One is to react with the lead on the positive grid to form lead oxide, which shows up as positive grid corrosion, an unrecoverable condition. The other option is to react with the active material (typically on the negative). This is known as the recombination reaction. While this reaction is not necessarily permanently destructive, like grid corrosion, it does have the effect of discharging the negative electrode. If the battery is on float, this shows up as increased float current. In addition, the recombination reaction is exothermic, so it adds to the heat load on the air conditioners.

The oxygen recombination efficiency of TPPL technology is high, like many other AGM batteries, but, unlike other AGM batteries, with TPPL technology, the rate of gas generation is reduced. This reduction in gas generation has the benefit of providing reduced operating temperatures, reduced float currents, and reduced positive grid corrosion. So, recombination efficiency is not necessarily the most critical measure of gassing behavior.

Low Self-discharge Rates

As describe previously, self-discharge is a secondary result of hydrogen gas generation in lead acid batteries. A reduction in

gas generation rate, as TPPL provides, will directly reduce the rate of self-discharge.

TPPL products show a reduced self-discharge rate compared to more conventional batteries. This means reduced issues associated with long supply lines to remote installations and reduced inventory management issues. Figure 6 illustrates the self-discharge rate of TPPL products,

including the DataSafe^® XE battery series and compares that rate to typical lead calcium batteries.

Lowest Cost of Ownership

The features and benefits of the DataSafe^® XE series of TPPL technology batteries give the UPS operator a battery that is smaller, lighter, more able to handle multiple hits and consumes less energy, and all while providing longer life and higher reliability. All of these characteristics help manage the long-term cost via lower purchase cost, less frequent replacement, reduced energy cost, and reduced care and maintenance of the battery string. Along with the opportunity to reduce the cost of temperature control in battery rooms come new options for where batteries can be located. As the first truly purpose-built battery for the modern critical UPS industry, the DataSafe^® XE battery series offers the best opportunity to minimize the lifetime cost of the battery.

You may also visit the website at www.enersys.com for any further details, or you could also please feel free to revert on the contact details mentioned below and it would be my pleasure to be of assistance.