The Baghdad Battery, the first known battery design, is over 2,000 years old.
It consisted of a clay casing, a copper cathode, an iron anode, and an acidic electrolyte, probably vinegar. On a conceptual level, it wasn’t too different from today's batteries, which also use an electrochemical reaction to supply power. However, battery efficiency has improved dramatically in the last two millennia. Lead-acid batteries rank among the most significant technological advances. Even after over a century of production, lead-acid batteries continue to improve.
Two such improvements are flat plate and tubular batteries.
These battery designs are popular choices for industrial battery applications. They’re similar in many respects, and the nuanced differences are often difficult to spot. However, selecting the best option for your application can make all the difference for your ROI.
Here’s what you need to know to choose between flat plate and tubular forklift batteries.
Like their Baghdad Battery predecessors, lead-acid batteries are electrochemical batteries.
As the name suggests, lead-acid batteries use lead alloys as the primary metal in galvanic reactions. At a basic level, these batteries consist of a lead cathode and anode submerged in sulfuric acid.
In a closed circuit, ions move between the cathode and anode, creating an electric current. Sulfate ions flow from the negative plate to the positive plate during discharge. During recharge, the direction reverses.
By definition, sulfate ions always flow from the cathode to the anode. Therefore, the positive plate is the anode during discharge and the cathode during recharge. To avoid confusion, this article and many others refer to the cathode and anode in their discharge state. From this point forward, the terms “cathode” and “negative plate” are interchangeable, as are “anode” and “positive plate.”
This reversible, stable reaction is what makes lead acid batteries reliable and rechargeable. Flat plate and tubular batteries use the same galvanic reaction and are very similar in most respects. They both use sulfuric acid as the electrolyte and a plate cathode.
Their defining difference is the anode design.
Flat plate batteries don’t use a solid lead plate.
Instead, their anode is a lead alloy grid. The grid design increases the anode’s surface area, allowing more contact with the electrolyte solution and active material. Flat plate batteries are inexpensive and reliable.
However, increased surface area has its pros and cons.
There are two primary advantages to flat plate battery design:
Lower Investment Cost. A flat plate is a simple, easily manufactured design. Consequently, these batteries are less expensive than tubular batteries. Both the initial setup cost and individual battery prices are around 30% lower than those of tubular batteries, making them a popular choice for tight budgets.
Heat Dissipation. All lead-acid batteries generate heat. Flat plates’ increased surface area dissipates heat faster than tubular designs. This makes the flat plate a smart choice for high-heat workspaces.
When considering this battery type, keep these two disadvantages in mind:
Positive Plate Growth. During cycling, the active material in the positive plate swells. This expansion is normal, but over time, it stresses the battery casing and the positive terminal. Flat plate batteries have no mechanism to control this swelling. Thus, they tend to experience grid-growth-related failures around the four- to five-year mark.
Shorter Lifespan. Factors like terminal design, casing materials, active material placement, and electrolyte concentration all affect battery longevity.
Many of these factors differ from brand to brand. However, unchecked positive plate growth in the flat-plate design damages terminals and casings, leading to cracks. Likewise, reduced contact between the plates and the swollen active material shortens battery capacity near the end of life. These factors frequently limit flat plate batteries to a five-year lifespan.
Tubular batteries ditch the grid in favor of vertical tubes.
A layer of active material covers each lead alloy tube, and a polyester sleeve covers the active material. The tube construction gives the positive plate more surface area than a flat grid, and the sleeves protect the active material.
That combination of surface area and protection is what separates tubular batteries from flat plate designs
Tubular batteries offer significant benefits for matched operational needs:
Longevity. One of the most significant limits on battery lifespan is positive plate growth. This growth occurs in tubular batteries, just like in flat plate batteries. However, the polyester sleeve constricts the active material, compressing swelling. This reduces grid growth and increases battery lifespan to around eight years.
Higher Amp-Hour Capacity. The larger surface area of a tubular positive plate holds more active material, so a tubular battery of the same physical size can deliver more amp-hours than a flat plate battery. For operations that need more capacity from the same battery compartment, that extra runtime is often the deciding factor.
Improved ROI. Improved battery lifespans mean fewer replacement batteries. Over an eight-year period, an operation might need to purchase two flat plate batteries rather than one tubular battery. Over this lifespan, most tubular battery users save around 30% per battery cycle.
The primary drawback to tubular batteries is initial investment.
Initial Investment. Tubular batteries are more expensive per unit than flat-plate batteries. Likewise, the initial setup cost is higher. However, when balanced against longevity, tubular batteries provide better ROI.
How and where your fleet uses industrial batteries makes a big difference.
As such, there is no “best” battery, only the best battery for your application. In fact, mixed applications sometimes benefit from a mix of batteries. The only way to know for sure is to examine your operation’s individual needs.
A power study is the fastest, easiest way to discover your real-world battery demands and make informed decisions.
We offer free power studies to support that crucial discovery period. Our experts install monitoring devices on your forklifts to determine your facility’s unique power requirements and provide you with a comprehensive report.
Then, we help you select the right batteries for your applications.
We offer complete motive power solutions, including flat plate and tubular batteries, for every budget. So, you’ll never have to compromise when it comes to keeping your fleet powered.
Let us empower your business. Schedule your risk-free power study today.
To learn more about industrial batteries or to schedule a free power study, contact us online or at one of our 15 locations:
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