Absorbed Glass Mat (AGM) vs Li-ion Battery
Executive Summary
· AGM is a relatively new technology compared to traditional lead-acid. AGM batteries no longer require daily maintenance like adding distilled water; however, they have many other disadvantages of lead-acid technology: limited capacity, inconvenient charging, voltage drop with battery discharge, energy losses due to battery heating, cooling requirements, and so on.
· These disadvantages typically do not allow a single-battery operation with an AGM technology. Two to three AGM batteries are required per forklift to be swapped between shifts.
· The total cost of ownership of a forklift fleet powered by AGM batteries is 20–40% higher than lithium-ion batteries.
· TPPL is a type of AGM that has one distinct advantage: a high charge absorption rate at the initial stage of charging; yet TPPL retains the key disadvantages of lead-acid batteries.
AGM battery meaning
What does AGM battery mean? Absorbed Glass Mat (AGM) is a modern variant of a lead-acid battery. This battery should not be confused with a gel battery because there are significant differences between these types. A gel battery is engineered using a gel paste that suspends the electrolyte inside the battery case. In an AGM battery, the electrolyte is stored in a glass mat and can never spill. AGM has a big safety advantage in a head-to-head comparison of AGM vs a standard battery.
For a hundred years lead-acid battery chemistry remained unchanged. The first significant technology improvement came with the introduction of the “pasting process” instead of flat plates in the construction of electrodes. These electrodes consist of a lead-alloy grid filled with a porous lead paste and can now provide more energy than foils or flat electrodes.
The second major modification was the use of AGM separators instead of conventional separators. This invention resulted in a sealed lead-acid battery, or SLA battery. In an SLA battery, including the AGM type battery, gas recombination occurs, and electrolyte concentration remains constant. Today an AGM deep cycle battery is widely used in pallet trucks, forklifts, and so on.
Another important modification was the use of pure lead instead of lead, calcium, and tin alloy in plates of decreased thickness, giving the technology the name “thin plate pure lead”, or TPPL. This new technology can absorb more charge than the standard AGM battery, and at a faster rate. However, this is only true for the initial stages of the charging process; the charging rate decreases sharply as the battery reaches a state of charge (SoC) of 70–80%. Charging time remains considerably higher than any lithium battery (for more information, see Lithium vs. TPPL Battery Overview).
Lithium-ion deep cycle battery
Most modern off-highway industrial vehicles, such as forklifts, can benefit from using lithium-based batteries. A power pack capacity may be in the range of 100 to 1000 Ah, though the capacity can be further increased by adding cells in series or parallel.
Material handling equipment has specific requirements based on the particulars of operations:
o Equipment utilization is high, with up to 18 work hours per day with short breaks.
o Chargers are located nearby.
o Unlike with an EV, battery weight is often welcome as a counterweight in bigger trucks.
You can learn more about the design of lithium cells used in forklift batteries here: What’s Inside the Black Box? The Form, Design, and Chemistry of Lithium Forklift Battery Cells.
Comparison of key technology indicators
