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Battery thinking

23 May 2018

Enersys considers its advanced lead acid battery solution Thin Plate Pure Lead (TPPL) in the light of ten factors important when upgrading a battery fleet.

While traditional lead-acid types remain popular and reliable, newer and more innovative lead-acid technologies, as well as alternatives such as lithium-ion (Li-ion) are giving operators more opportunities to improve operations and reduce TCO.

Below are ten key points for users to consider while seeking to benefit from these new technologies:

1 Downtime

Challenge: When using vehicles with traditional batteries in multi-shift operations, production time is lost as discharged batteries must be exchanged. The spare batteries required also incur extra cost and space requirements.

Solution: Thin Plate Pure Lead (TPPL) VRLA batteries allow vehicles to be used continuously, even in a multi-shift environment. TPPL batteries accept high charge rates, and allow opportunity charging during natural breaks within a shift; the batteries stay within the truck, so swap out time is eliminated.

2 Charging

Challenge: Flooded cell batteries release oxy-hydrogen gas and acid vapours during charging. Therefore, they must be charged within a dedicated room with extraction capability to avoid health risks and product contamination.

Solution: Choose batteries that do not gas during charging to eliminate these risks. The cost and space of supplying an equipped charging room is avoided, as is the disruption of vehicles traversing between production, warehouse and charging areas.

3 Maintenance

Challenge: Flooded cell batteries have a significant maintenance requirement, with a need for regular water top-ups. These are time-consuming, pose risks for operators and to the factory floor and, in larger facilities, incur substantial water bills.

Solution: More recent VRLA lead-acid types save maintenance time, risk and costs as their internal recombination processes mean that they do not require water top-ups.

4 Costs

Challenge: Flooded lead-acid batteries require overcharging levels of 10-20% to generate acid mixing and minimise stratification. This adds to the facility’s energy costs and impacts its green footprint.

Solution: Battery technologies available today require lower overcharging, at typically 8-10%. Up to 30% energy savings can be achieved by using such batteries with suitable chargers.

5 Replacement

Challenge: Ongoing capital costs for traditional batteries are higher than necessary because of their operational life cycle limits.

Solution: Innovative lead-acid batteries offer cost-savings through improved operating life, with expectation of 1500 – 1600 cycles at 60% Depth of Discharge (DoD) for current designs. They are ideal to be used in Partial State of Charge (PSoC) applications.

6 Space

Challenge: Compact trucks are required for narrow aisles and other confined areas.

Solution: Plate sizes have reduced from 9 mm to just 1 mm thickness in some products; this allows 30% space savings compared with equivalent AGM types.

7 Storage

Challenge: Conventional batteries must be recharged once every six to twelve weeks during storage. Resources are required for monitoring the open circuit voltage of batteries in inventory, and boost charging when necessary.

Solution: Latest-technology lead-acid AGM batteries can be stored for up to two years at 68°F when starting from a fully-charged condition; this reduces the monitoring and boost charging requirement and cost.

8 Capital costs

Challenge: There is widespread industry interest in Li-ion batteries as a replacement for lead-acid, but one drawback of Li-ion technology is its cost.

Solution: The latest lead-acid battery technologies, while offering many technical advantages, have a cost factor of 1.4 to 1.6 compared with standard lead-acid types. By contrast, many Li-ion batteries carry a historical cost factor of 4 to 6 over lead-acid.

9 Recycling

Challenge: As all batteries have finite operating lifetimes, disposing of them responsibly with minimal environmental impact and cost is always a concern.

Solution: Against this background, Li-ion batteries present difficulties. All Li-ion types must be chemically analysed to determine whether they contain any valuable materials. Lithium iron phosphate (LFP) battery recycling is currently hardly worthwhile, while with lithium cobalt oxide (LCO) batteries the cobalt can be recovered and corresponds to about 10 per cent of the new cell value. However, Li-ion recyclability is anticipated to improve. Lead-acid batteries, however, are easily and virtually completely recyclable.

10 Robust batteries

Challenge: Batteries can be subject to harsh environments, with shock and vibration, wide temperature ranges and heavy-handed treatment from inexperienced operating personnel.

Solution: The grain structure of the pure lead used in TPPL batteries makes the plates far less susceptible to corrosion. The batteries are also resistant to harsh shock and vibration conditions, due to their rugged construction and a vibration-resistant compound. They also have a much wider operating temperature range than other lead-acid battery designs.