Using modular chargers with carefully

designed charging profiles eliminates this tendency and prolongs battery life.

• KEEPING TRACK OF ENERGY SAVINGS POTENTIAL Modern, modular battery chargers are known to offer energy-saving benefits – but what is actually possible? For example, internal tests have shown

that, depending on locally prevailing energy costs, a 120V 1500Ah battery that would typically cost €50 to charge using a ‘50Hz’ charger would cost approximately €37 with the modular charger type. This represents significant possible savings when multiplied over the entire battery fleet’s daily operations.

by Martin Walsh, EnerSys EMEA W

arehouse operators are under continuous pressure to handle

stock more quickly, and maximise power efficiency while doing so. One reflection of this is a growing trend to replace heavy duty internal combustion engine fork lift trucks with electrically-powered types. These larger electric trucks need larger batteries, together with chargers capable of charging them efficiently, quickly and reliably. These challenges can now be met using

High Frequency (HF) technology modular chargers. Capable of supporting 96V and 120V operations, and ratings to 21kW, they allow charging of the largest electric materials handling vehicles. Below is a list of key issues that such chargers must overcome to improve productivity and power efficiency for users operating trucks of all sizes.

• SUPPORTING LARGER-SIZED MATERIALS HANDLING VEHICLES Until now, a solution for charging 120V batteries at 21kW has not been available on the market from a large industrial charger manufacturer; the legislative and technology barriers have been too high. Modular chargers with the correct HF

technology can now overcome these barriers. This means that owners can support vehicles of all sizes with a single charger range. Additionally, the chargers’ modular design adapts to a wide range of battery capacities, allowing a potential reduction in the number of chargers on


site; freeing-up valuable space while improving charging flexibility.

• MAXIMISING POWER EFFICIENCY As warehouse operations intensify, use larger-capacity vehicles and consume more power, improving power efficiency has become essential. Because of their high-frequency design

and modular topology, modular chargers can achieve OPEX savings over the traditional ‘50Hz’ charger types. This can be further improved through the use of modern batteries with more advanced technology and lower input impedance.

• MAINTAINING POWER EFFICIENCY THROUGHOUT THE ENTIRE CHARGING CYCLE As a battery approaches full charge, its load on the charger reduces; this causes traditional chargers to operate less efficiently. Modular chargers can have up to six

modules sharing the load. These are progressively switched off as the load falls, so the modules remaining on line stay well-loaded and efficient throughout the entire charging cycle.

• ENERGY WASTAGE AND REDUCTION IN BATTERY LIFE THROUGH OVERCHARGING Conventional chargers tend to overcharge their connected batteries by up to 20 per cent; this wastes energy and can reduce battery life.

Life iQ charger

• ACHIEVING HIGH RELIABILITY As warehouses face ever-increasing pressure to move stock fast, they cannot afford to lose productivity through an inoperable charger. Modular chargers share the load across

their multiple modules. If one fails, the others continue to support the load at reduced power without stopping the charging process. For particularly critical operations, extra modules can be added for N+n redundancy.

• REDUCING THE CHARGING TIME Chargers can adversely affect warehouse productivity through excessive charging periods as well as by failing. Using optimised charging profiles

reduces charging times by one or even two hours, depending on battery type.

• INCREASING MAINTENANCE INTERVALS Further loss of productivity arises if maintenance interval periods must be shortened. As each 60 litre water top-up can take 20 to 30 minutes, with the battery being unavailable for use, this is another strong consideration. Intelligent charging can extend the

maintenance intervals for some batteries to up to eight weeks, compared with just one week to 10 days for conventional chargers.

EnerSys T: +44 (0) 1617 944 611

• MITIGATING THE EFFECTS OF POOR POWER FACTOR Conventional chargers with a poor input power factor mean that supply cabling and switchgear must be upsized, while the mains supply is overloaded with reactive power and subjected to AC distortion.


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