First we are going to look at a table that indicates some factors between the Flat plate and Tubular plate lead acid batteries:
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Flat Plate
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Tubular
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Explanation of tubular advantages
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Charge cycles
(at 80% DOD)
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100–1000
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1100–1800
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Reliability
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Reliable
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More reliable
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Electrolyte
stratification risk
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Medium
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Low
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The external shape of the positive plate allows for easier movement for the electrolyte
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Float current
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Medium
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Low
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Thermal management
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Medium
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High
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Because of the higher relative electrolyte amounts and easier convective heat transport
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Interface
surface area
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Medium
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High
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Electrical resistance
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Mid-to-Low
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Low
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Well-defined pore sizes permit easy movement to the electrolyte
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Life expectancy
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15–18 years
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20+ years
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Charge retention
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Long
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Longest
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Because there is no electrolyte pollution from reinforcing agents
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Why tubular is looking better? The secrets are the multi-tube bag gauntlet and increased surface area of the positive plate.
Advanced multi-tube bag gauntlets are constructed of 100% polyester high-tenacity, multifilament yarns that are impregnated with an acrylic resin system and fixed crosswise to the tubes, while spun yarn is used lengthwise.
Gauntlet Characteristic:
• High porosity and low electrical resistance – Low electrical resistance can determine a well-defined pore size that permits easy movement to the electrolyte, but at the same time reduces the active material shedding to a negligible amount
• Good mechanical resistance and elasticity – The gauntlet resists the high pressure that the active material produces during its cyclical expansion. The fabric holds the paste pressed to the conductive lead spines ensuring stable performance. Mechanical resistance to abrasion during cell assembly reduces scraps and pollution
• Reduced release speed of antimony – The fabric keeping the active material all around the spines acts as a filter for the electrolyte, reducing the release speed of antimony from positive grids. In contrast, for pasted plates there is almost no distance between grid wires and electrolyte
• Semi-rigid stability – The semi-rigid woven fabric gives the multi-tube bag a stable shape that permits an easy and quick filling procedure with paste, powder or slurry methods
• High short-circuit resistance – Gauntlets can be supplied with a special solution for the two lateral tubes that result in dramatic increase in plate short-circuit resistance. In particular, the ISM solution (where the external tubes have half of their fabric completely closed) gives the best protection against short circuits between positive and negative plates with only a minor increase in electrical resistance
Due to increased positive plate surface area, tubular batteries have 20% more electrical capacity than flat plate batteries of comparable size and weight. With less positive plate shedding, tubular batteries also provide up to a 30% longer service life than flat plate batteries. In addition, battery engineers attest that tubular cells are more widely used because they deliver energy at a faster rate.
Other Stationary Tubular Advantages
Doubters of tubular construction might argue that flat plate batteries — due to their simpler construction — are generally less expensive to make and maintain. However, tubular batteries have been shown to have both a longer life and supply more power faster in an equivalent size, while still being produced at a competitive cost.
Tubular plates deliver energy faster due to:
• Compact structure
• Increased mass and surface area of the active material
• Ease with which acid circulates around the tubular plate design
Perhaps most importantly to
stationary applications, the tubular positive grid does not require horizontal bars, which virtually eliminates positive plate growth and therefore post seal leaks and jar cracking. As a result, in applications which require a long service life,
tubular plate batteries provide the best and most reliable power for the money spent.
