SMF batteries: What’s new this summer?

Perceptions about batteries are changing fast, especially with industrial users realising that a battery is a critical link to ensure backup power. Today, sealed maintenance free (SMF) batteries are the most popular technology used in a host of applications—from small UPS systems to large systems deployed in huge industrial plants. SMF batteries do not need maintenance and are pollution free.

By Srabani Sen

Tuesday, June 14, 2011: The SMF battery industry is, thus, growing year by year. Currently, this technology is widely used in the telecom and power sectors, and to some extent in the railways. Of late, the solar power industry also offers good scope for the growth of SMF batteries.

“Nowadays, customers are becoming more aware and don’t mind spending a few hundred rupees more for SMF batteries. They know about the disadvantages and hazards of lead acid batteries,” says Kunwer Sachdev, managing director, Su-Kam Power Systems Ltd.

NEW TYPES AVAILABLE IN THE MARKET

SMF VRLA batteries are far superior to conventional batteries. Their plates are made of lead calcium, which offers a longer life and higher efficiency due to low self discharge. SMF batteries are also environment friendly, require less space, and can be used in any position.

If we go by the rated capacity, SMF VRLA batteries broadly fall into three segments—small: 3 to 17 Ah; medium: 26 to 200 Ah; and large single cells: 2V 100 Ah to 2V 3000 Ah. Su-Kam offers SMF batteries from 4.5 Ah to 200 Ah, which are based on absorbed glass mat (AGM) technology. The company claims its batteries offer the best backup and a long life. “Its radial grid design enhances the performance of high rate discharge, while thicker grids and corrosion resistant alloys ensure a longer life,” explains Kunwer Sachdev.

Exide offers Powersafe and Powersafe NXT, which are highly reliable and are known for their quality. The Powersafe range was extended in 2010 by introduction of Powersafe NXT series. The hallmark of NXT is its enhanced deep cycling ability, faster recharge capability and superior life. It carries a warranty of three years.

Powersafe NXT is yet another unique product from Exide, which is developed by its R&D centre, keeping the customers’ technical needs and operational requirements. The wide portfolio of products, alongwith Exide’s sales and service network in the country offers, a unique and customised value proposition to all users in sectors like banks and financial institutions, insurance, IT and ITES, hospitals, education and many others. “Exide Powersafe range of SMF VRLA batteries for UPS application has been a preferred choice of customers and end users for the past decades,” claims the company spokesperson.

AGM and gel batteries: Currently, AGM batteries and gel (or gel cell) batteries are very much in demand across India. These are often colloquially called sealed lead acid batteries, but they always include a safety pressure relief valve. As opposed to vented (also called flooded) batteries, a VRLA battery’s electrolyte does not spill if it is inverted. VRLA batteries also use much less electrolyte (battery acid) than traditional lead acid batteries. High rate discharge batteries are also much in demand.

According to Sunil Bhatnagar, director, sales and marketing, Artheon Electronics Ltd, the fastest moving batteries in the market are SMF batteries with AGM separators, gel batteries, pure lead tin (PLT) batteries, traction batteries, batteries for e-bikes, generator starting batteries, solar lantern batteries, emergency lighting batteries and batteries for the telecom sector. Artheon offers SMF batteries from 4.5 Ah to 200 Ah, which are based on AGM technology. These are designed for tough solar applications, are tested at Solar Energy Centre, Ministry of Non Renewable Energy (SEC-MNRE) and are suitable for home lights, streetlights and solar lanterns. Apart from this, Artheon also sells North Star’s thin plate technology batteries for solar and telecom applications. These batteries have very thin plates and get charged very fast; hence, they save about 80 per cent of the cost of running a DG set.

Amptek has introduced SMF batteries for motorcycles, e-bikes and LED lighting. It has seven models of SMF motorcycle batteries—12V 2.5 Ah, 12V 5Ah, 12V 7Ah, 12V 9Ah, 12V 3Ah and 12V 4Ah. Amptek has also introduced various 4V SMF batteries exclusively for LED lighting applications like LED torchlights, LED solar lanterns, LED emergency lights, etc. Amptek batteries also offer deep cycle features, designed to be deeply discharged using most of its capacity.

Deep cycle batteries: Computech Systems is all set to launch deep cycle batteries. “Deep cycle batteries are designed to be discharged by as much as 80 per cent, time after time, and have much thicker plates. The major difference between a deep cycle battery and others is that the plates are made of a solid grid and lead of the highest purity. Although these can be cycled down to a 20 per cent discharge, the best way to get the optimum lifespan for the cost, is to keep the average cycle at about 50 per cent discharge,” informs Vikas Aggarwal, CEO, Computech Systems. These batteries comply to Japanese quality standards, which is acceptable to the Indian government.

Regnant offers deep cycle batteries that give 600 cycles at 75 per cent depth of discharge (DOD) or 700 cycles at 50 per cent DOD. Regnant is promoting the use of deep cycle gel technology batteries using 4BS technology in the solar industry to ensure long life for batteries used in solar cyclic applications.

“According to Japanese JIS standards, for normal SMF VRLA batteries, the recommended DOD for 500 cycles of charging/discharging is 50 per cent, which means that, effectively, only 50 per cent of the available capacity will be used. However, due to several reasons, especially in areas with poor power availability or where users are dependent on solar power, it is not always possible to achieve this. Therefore, for these applications, deep cycle batteries are ideal,” explains Praveen Kumar Sood, chairman, Regnant Energy Solutions.

“Due to the growing demand from portable LED equipment manufacturers, we also offer a more cost effective 4 V 4.5 Ah model. When the forward voltage drop of major white light LED emitters is in the region of 3.2-3.5 V, with a simple constant current driver, you can efficiently power these with 4 V SMF VRLA batteries instead of 6 V. In the case of the latter, you can drop the additional power using a resistor, which is a total loss,” explains Praveen Sood.

Greenvision Technologies Pvt Ltd offers deep cycle batteries designed to perform better in the extreme conditions faced in India. “We also have a model—SPG 12-9—which is specifically meant for solar lamps and CFL UPS applications. It has a much better life than the conventional 7 Ah batteries,” says Biju Bruno, managing director, Greenvision Technologies Pvt Ltd.

HBL Power Systems has developed two new series of SMF batteries using lead acid technology, and the products are suitable for both domestic and export markets. These are called Triumph Tubular Gel VRLA battery and Triumph Plus (advanced) VRLA battery. “These batteries are innovatively designed with a with a tubular positive plate and gelled electrolyte. This technology encompasses the features of tubular technology with maintenance free characteristics,” explains Avnish Arora, vice president, sales, HBL Power Systems Ltd

Luminous Power Technologies offers SMF batteries that are suitable for deep cycle applications, and which can be used in rural areas that suffer from power deficit. These batteries are available in 12 V from 7.5 Ah to 200 Ah.

Truepower International Ltd also has SMF VRLA batteries for different segments in the range of 4.5 Ah to 200 Ah, with a superior high rate discharge and low internal resistance. Its thicker grids and corrosion resistance alloys help ensure a longer life and better output.

TECHNOLOGICALLY ADVANCED FEATURES

In the age of innovation, the battery industry has not been left behind. “Keeping up with the demands of customers, SMF batteries are now designed to provide outstanding performance to withstand overcharge, over discharge, and to resist vibration and shock. Compact in size, these batteries save installation space, while providing full and reliable power,” explains Kapil Sood, CEO, Fusion Power Systems.

Gel technology: Fundamentally, the latest trend in the SMF category is the gel battery. This essentially incorporates all properties of a pure lead acid battery but has a much longer lifespan, better manageability, is leak proof and is more effective in terms of amperage and current delivery. “The key reasons being that gel has its viscosity alive for a much longer duration, does not dry up as acid does, is mouldable in different types of casing, and consumes less space within the battery shell (plastic container), and therefore, a smaller size can give a higher potential,” says Aditya Arora, COO, Base Corporation.

Another development is to add gel in batteries to improve the water retention during the charging and discharging recombination cycle. This improves the heat characteristics of the battery, as this is also one of the reasons for premature failure of batteries in India due to its climatic conditions and usage patterns, wherein proper ventilation is not provided at the place where batteries are installed, making them vulnerable to high operating temperatures. This results in obtaining a lower capacity, a fewer charging/discharging cycles, or both.

In a gel battery, sulphuric acid is mixed with silica fumes, which makes the resulting mass gel light and immobile. Unlike a flooded wet cell lead acid battery, these batteries do not need to be kept upright. Gel batteries reduce the electrolyte evaporation and spillage common in wet cell batteries, and boast of a greater resistance to extreme temperatures, shock and vibration. Chemically, they are the same as wet batteries except that the antimony in the lead plates is replaced by calcium.

HBL has innovatively designed a tubular gel battery with a tubular positive plate and gelled electrolyte. “The tubular plate is proven for cyclic and deep discharge performance. The cyclability of tub gel under PSoC is much higher than that of flat plate VRLA batteries,” says Avnish Arora. Excess electrolyte content in the form of gel helps ensure a good deep discharge recovery and better thermal management. This feature of the Triumph tubular model enables users to achieve a great reduction in operation expenses. This battery also uses pressure die-cast circular spine grids, which has excellent corrosion resistance, leading to higher service life. Its Triumph Plus batteries are a by-product of the effort to optimise the performance of flat plate technology in order to achieve higher service life with improved reliability. Besides the special lead alloy combination, these contain a smaller amount of gel to improve the thermal efficiency of flat plate VRLA batteries.

Absorbed glass mat: AGM is an advanced technology used in SMF batteries that eliminates water loss. Once the battery is filled with acid, the battery is permanently sealed and there is no need to top it with water or check the acid level. In batteries using AGM technology, electrolyte is absorbed into a mat of fine glass fibres. The plates in an AGM battery may be flat like a wet cell lead acid battery in a rectangular case.

In cylindrical AGMs, the plates are thin and wound into spirals, like most consumer disposable and rechargeable cells. The spiral construction allows purer lead in the plates, since the plate no longer needs to support its own weight as in traditional cells. “The specific power of these batteries is very good and they can be charged and discharged quite rapidly. However, their specific energy tends to be lower than the traditional flooded batteries,” explains Rakesh Malhotra, founder and managing director, Luminous Power Technologies Pvt Ltd.

Deep cycle: The latest innovation in this sector seems to be the deep cycle batteries. Deep cycle batteries are based on 4BS technology and can be easily charged even after deep discharging. The entire charging process is also faster compared to a normal SMF VRLA battery of the same capacity.

Grid technology: Another latest technology being used is expanded grid technology, by which thinner grids can be obtained to hold more active material. This increases the energy density of the batteries by reducing the lead required and thus reduces the cost. Many manufacturers are trying to switch over to it.

“There is a trend towards using better methods to chemically process the battery (to prevent electrolyte loss), use purer lead (to prevent plate corrosion), adopt newer technologies in the charging equipment (to improve battery life), and incorporate thicker plates (to decrease charging time),” says Aditya Arora.

Says Sunil Bhatnagar, “Nowadays, batteries are made for specific products or use, like for e-bikes, generators, solar applications, etc. This is done by closely monitoring chemical compositions and charging techniques. Manufacturers are spending on R&D to find the right chemical composition and charging technique.”

“SMF VRLA batteries have very low permeability, low resistance current path and fast recharge capability,” says Rajesh Gupta, director, Okaya Power. “We use inter cell welding of the inner cell, which provides a very low resistance current path. We also use an extra thick special alloy for very long life and to prevent water loss,” he adds.

Improved battery life: Advances are also taking place in reducing corrosion and improving battery life through various combinations of the plate paste mix. The process of battery charging is being experimented with the trial of different techniques including the use of fuzzy logic. “Usage of corrosion resistant alloys for longer life, innovative formulated paste for deep cycle applications, and low gas emitting alloys (Pb-Ca-Sn-Al) are, therefore, becoming common,” points out Ravi Mundra, CEO, Truepower International Ltd.

Discharge rate: SMF batteries were earlier available only for the C20 discharge rate. However, these batteries are now being designed for C10 as well as the C5 discharge rate. Manufacturers worldwide are trying various constituents to make lead acid batteries much lighter and more durable. They are using lead acid batteries with electrodes modified by adding calcium for low maintenance, low overcharging, low self discharge and a longer life.

Physical appearance: Another innovation is the smaller size of the front terminal batteries. “With a height of just 48.26 cm and a width of 58.42 cm for the industry standard panels in which battery banks are installed, we have made slim, low height and narrow front terminal batteries available. These make maintenance as well as staking very user friendly, requiring less floor space. These models are good for telecom station microwave towers or other places where office space is less. Power generating and distribution centres, railways, solar/wind power storage stations, etc, use these batteries. Also, for the various portable LED based solutions that require rechargeable batteries, we offer 4 V batteries from 0.7 to 4.5 Ah,” says Praveen Sood.

Buying tips

Long life, warranties, service support and competitive prices are some of the requirements of buyers. There is a growing requirement for gel batteries for solar and LED based lighting. Also, the market for deep discharged VRLA batteries is picking up.

However, if no effort goes into selecting the right solutions for backup power storage, it can lead to a situation where an office’s entire operations come to a standstill because of the unavailability of power.

Lack of awareness among consumers about the importance of the quality of batteries is one reason why most manufacturers and marketers do not bother about setting international standards for their products, introducing superior technologies or offering quality service. A battery is a consumable and has a definite service life, which can be maximised by users, provided they know how to choose the right product with the most appropriate features, ensure proper installation and follow ideal usage patterns.

“Customers should be informed about what batteries are being supplied and ask questions about the company, brand, support network, replacement policies, quality, life of the battery, etc. It is also important that they check on the quality of the UPS system or other equipment that they will use with the battery. In most cases, batteries are abused rather than used, simply because the solution provider is unaware of or ignores the basic precautions to be taken during installation,” informs Biju Bruno.

Sunil Bhatnagar suggests that buyers should select the right battery for specific applications and never compromise on quality because of price. “Always inform the battery company about the application in order to select the right battery. Also, avoid undersizing or oversizing the battery for a certain product. In short, buyers should look for reliability, good quality, timely service, technical support, lower cost of operation and long trouble free battery life.”

A buyer should be able to distinguish between a battery that uses pure lead and one with recycled lead. “In case a vendor is offering a battery at a very cheap rate, it means that the battery has recycled lead. Such a battery may initially offer good results but will eventually fail in a couple of months,” adds Ravi Mundra. A buyer should, therefore, purchase only from a known and established vendor and do a thorough background check of the company.

“Unscrupulous manufacturers and grey market operators can offer a cheaper product, which will not yield a proper return on your investment. Such batteries usually have a high internal resistance, resulting in an actual realised capacity that’s much lower than what is claimed, and even self discharge tends to be unusually high,” warns Rakesh Malhotra.

Adds Vikas Aggarwal, “Buyers should buy products that go through genuine quality tests. For example, all our products have test reports from government approved independent test labs. Buyers should also check the background of the company. Computech Systems has credibility in the battery market with its experience of 15 years.”

“For consumers, it is advised to buy batteries from authorised dealers, thus ensuring that they acquire only original brands. Cheap batteries from unreliable sources could be found underperforming and may also be hazardous. For OEMs, it is advised to evaluate batteries properly before approving any particular brand or buying batteries from new sources. OEMs can be attracted by aggressive prices and terms but a field problem can cause a much bigger loss, when compared to a minute difference in the initial price,” concludes Aditya Arora.

Products and their Features

Note: The names of the companies are in alphabetical order.

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