Sealed maintenance free (SMF) batteries, which are also pollution free, are becoming popular for a host of applications—from small UPS systems to large systems deployed in huge industrial plants. Currently, this technology is widely used in solar, telecom and power sectors, and to some extent in the railways. Despite its price being on the higher side, SMF batteries are becoming popular as customers are now more aware and do not mind spending a few hundred rupees more for these batteries, as they are safer than conventional batteries.
Thursday, February 23, 2012: What’s available in the market?
The plates of SMF VRLA batteries 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. Based on their rated capacity, SMF VRLA batteries broadly fall into three segments—small, which is 3 to 17 Ah; medium: 26 to 200 Ah; and large single cells: 2V 100 Ah to 2V 3000 Ah.
Absorbed glass mat: Absorbed glass mat (AGM) is an advanced technology used in SMF batteries that eliminates water loss. Once the
battery is filled with acid, it is permanently sealed and there is no need to top it with water or check the acid levels. “In batteries using
AGM technology, the 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,” informs Biju Bruno, managing director, Greenvision Technologies Pvt Ltd.
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. “AGM batteries always include a safety pressure relief valve, which vented (or flooded) batteries do not,” adds Biju Bruno.
Artheon Electronics Ltd offers SMF batteries from 4.5 Ah to 200 Ah, which are based on AGM technology. These are designed for all types of solar applications. It manufactures 2 V, 6 V and 12 V batteries in a joint venture with North Star of USA. “Artheon has a state of the art battery plant in Nasik and has invested more than Rs 750 million in the plant and machinery,” informs Sunil Bhatnagar, director, sales and marketing, Artheon Electronics Ltd. Artheon also offers North Star batteries based on thin plate technology, which are capable of a very high rate of charge and discharge. “These batteries are suitable for all telecom and solar applications where the partial state of charge (PSoC) conditions are much prevalent. “This battery technology is particularly suitable for Indian conditions, where in certain remote areas, power cuts go on for 14-16 hours,” adds Sunil Bhatnagar.
Base Corporation offers SMF batteries in the range of 6 V and 12 V, and from 1.2 AH to 100 AH in the VRLA segment. “We constantly make an effort to introduce the latest technology to make our batteries more reliable, user friendly and maintenance free. These batteries have a long life and are highly recommended for standby applications,” informs Aditya Arora, COO, Base Corporation. Base SMF batteries are based on AGM technology along with an electrolyte suspension system. Moreover, the effective gas recombination system needlessly eliminates any sort of maintenance like frequent topping up. The re-charging time of these SMF batteries is much less compared to that of flat plate or tubular plate batteries. Additionally, compact designs with immobilised electrolyte make these SMF batteries perfect for sophisticated low maintenance and space restricted applications.
Gel batteries: The latest trend in the SMF category is gel batteries. These batteries essentially incorporate all the properties of a pure lead acid battery, but have a much longer lifespan, better manageability, are leak proof, and are more effective in terms of amperage and current delivery. “The key reasons are 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 (a plastic container), and therefore, a smaller size can give a higher potential. This battery has a better operational life than those based on AGM technology, even at higher temperatures,” says Aditya Arora.
In a gel battery, sulphuric acid is mixed with silica, which makes the resulting mass of gel, light and immobile. Unlike a flooded wet cell
lead acid battery, these do not need to be kept upright. Gel batteries reduce the electrolyte evaporation and spillage common in wet cell batteries, and greater resistance to extreme temperatures, shock and vibration.
HBL Power Systems has developed two new series of SMF batteries using lead acid technology, and the products are suitable for both the domestic and the export markets. These are called the Triumph tubular gel VRLA battery and the Triumph Plus (advanced) VRLA battery. “These batteries are innovatively designed with a tubular positive plate and gel electrolyte. Excess electrolyte content in the form of gel helps ensure a good recovery after a deep discharge and better thermal management. This feature of the Triumph tubular model enables users to reduce operational expenses. This battery also uses pressure die cast circular spine grids, which have excellent corrosion resistance,
leading to higher service life. This technology incorporates the features of tubular technology with its maintenance free characteristics,” explains.
On the other hand, Triumph Plus batteries are a by-product of the effort to optimise the performance of flat plate technology in order to
achieve a 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. HBL has also launched a specialised PLT based SMF battery called ‘Ignite’ for retail automotive market. These batteries are manufactured in Nandigaon plant, Hyderabsd. HBL Ignite is a pure lead tin battery, suitable for both heavy and light motor vehicles. These are technologically advanced—high cranking current is achieved by employing thin plates of pure lead tin which have more active surface area compared to conventional flooded battery. A smaller capacity of PLT battery can replace the higher capacity of conventional battery. HBL has increased the number of plates in Ignite, which results in more cranking power in comparison with flooded batteries.
Deep cycle batteries: Deep cycle batteries are also based on the latest 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.
Greenvision Technologies offers deep cycle batteries designed to perform better in the extreme conditions faced in India. “These batteries have a much longer life than the conventional 7 Ah batteries,” says Biju Bruno.
Computech Systems is all set to launch gel batteries for motorcycles and e-bikes, along with 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 ensure 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 accepted by the Indian government, and are suitable for solar applications as they have a long life. Computech Systems also offers SMF batteries in the brand name ‘ipower’ for weighing scales, UPS systems, electronic bikes, emergency lights, etc.
Okaya Power Ltd manufactures SMF VRLA batteries and VRLA (2 V cells) for industries. “We have a wide range
of products, from 12 V/7.2 Ah to 12 V/200 Ah, and in the 2 V cell range, we manufacture 200 Ah to 3000 Ah,” informs Rajesh Gupta, director, Okaya Power Ltd. These batteries have very low permeability, a low resistance current path and fast recharge capability. “We use the design of an inter-cell weld for the inner cell, which provides a very low resistance current path, and we use an extra thick special alloy, which gives the battery a very long life and also prevents water loss,” adds Rajesh Gupta.
Amptek has introduced SMF batteries for motorcycles, e-bikes and LED lighting. It has seven models of SMF motorcycle batteries—the 12 V 2.5 Ah, 12 V 5Ah, 12 V 7Ah, 12 V 9Ah, 12 V 3Ah and 12 V 4 Ah. Amptek has also introduced various 4 V
SMF batteries exclusively for LED lighting applications like LED torch lights, LED solar lanterns, LED emergency lights, etc. “To keep up with the demands from 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. “The self discharge rate for Amptek SMF batteries is about 2-3 per cent per month at room temperature compared with 20-30 per cent for other common battery systems. We also utilise thick and massive calcium grids, to give our batteries a long service life. Since the internal resistance is low, the battery can provide a high rate of discharge. Amptek SMF batteries are rated at 20°C and will operate from -60°C to +60°C when fully charged,” adds Kapil Sood.
Another new technology being used is the 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.
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 of discharge and low internal resistance. Its thicker grids and corrosion resistance alloys help ensure a longer life and better output.
Latest trends and innovations
According to Aditya Arora, the trend is to use better methods to chemically process the battery (to prevent electrolyte loss), use purer lead (to prevent plate corrosion and water loss), adopt newer technologies in the charging equipment (to improve battery life), and incorporate thicker plates (to decrease charging time).
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 techniques.”
Improved battery life:
Through the use of various combinations of the plate paste mix, there have been advances leading to reduced corrosion and improved battery life. The process of battery charging is also being experimented with,; including the use of fuzzy logic. “The use of corrosion resistant alloys for longer life, innovative formulated paste for deep cycle applications and low gas emitting alloys (Pb-Ca-Sn-Al) is, therefore, becoming common,” points out Ravi Mundra, CEO, Truepower International Ltd.
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.
Another innovative improvement is the smaller size of the front terminal batteries. Batteries are now coming in models that are slim, and of low height with narrow front terminals. This makes maintenance as well as stacking very user friendly, apart from 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. They are also suitable for the various portable LED based solutions that require rechargeable batteries.
Key benefits of SMF batteries
- High quality and outstanding stability
- Maintenance free operation
- Multi-position usage
- Explosion resistant
- Compact design
- Leak proof/spill proof
- Multiple applications
- Operate over a broad range of ambient temperatures
- Long shelf life
- High discharge rate capability
- No corrosive gas generation
- Long service life
- Comply with Japan Industrial Standards
- Lead calcium grid alloy
- Absorbed glass mat technology
- Mono block ABS container
- High energy density
- High recovery capability
- Electrolyte suspension system
- Equipped with low pressure safety venting system
- Effective gas recombination system
- Computer controlled battery formation
- Manufactured at state of the art, world class, manufacturing plants
- 100 per cent visual and electrical inspection
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