Lithium ion revolution?

Published:  08 July, 2011

Standfirst: At the recent CeMat show in Hannover, Germany, there was a considerable amount of interest shown in a power source technology that many believed could revolutionise the forklift truck industry. Gus Whyte, sales director – National Accounts and Systems at Hoppecke Industrial Batteries – puts the hysteria into context. 

One of the most important goals for warehouse operators and others involved in lifting, handling and storage of materials is to get the absolute maximum efficiency and productivity out of the equipment they use.

In terms of the forklift truck, reach truck, powered pallet truck, high or low-level order picker, this means making sure the vehicles are up and running in the operation as much as is physically possible. And the main element in any truck that controls its level of 'uptime' is the battery.

It would be no exaggeration to say that most operators in the materials handling industry do not fully understand the options available to them in terms of fork lift truck batteries. And a great deal of them are certainly unaware of how choosing the right battery can make a massive difference to productivity, efficiency and – ultimately – the success of their business.

The vast majority of fork lift trucks use lead acid batteries, mainly because they are the most economic and most recyclable on the market. Hoppecke Industrial Batteries – which has supplied batteries to some of the leading names in materials handling for decades – converts over 60% of used lead acid batteries into brand new manufactured items.

One of the main problems associated with standard lead acid batteries, however, is that like a car battery they have a limited amount of capacity that can be used between time consuming recharge periods. This could mean the possibility of them running out of power during an extended working shift, creating a real problem in the middle of a busy warehouse.

Other disadvantages include the fact that the batteries' deionised water reserves need to be replenished roughly once every week and it can take between 8 and 12 hours to recharge a lead acid battery, which may have to be removed from a fork lift truck and put into a special charging area. Also, lead acid batteries degrade over a period of time and release hydrogen gases during this recharge cycle. And the highly corrosive elements of lead and acid mean that the batteries need to be handled with great care.

That isn't to say that lead acid batteries are a bad choice for warehouse operators, of course. Indeed, many vehicles powered this way are in operation 24 hours a day, seven days a week.

To counter many of the issues associated with lead acid batteries Hoppecke has created its Trak-Air range of products, which includes batteries and high frequency chargers. Trak-Air batteries have a much longer life than standard batteries, which cuts down on replacement and disposal, and they reduce expensive energy use by over 30% and water consumption by up to 70%. At the sametime, the high frequency chargers can cut charging times to around 2.5 hours when used in conjunction with a rapid charge system.

However in certain operations, a better alternative than lead acid is the fibre nickel cadmium (FNC) battery which combines high energy density with high levels of resistance to cycling, minimal susceptibility to vibration and shock, greater long-term stability and considerably longer life expectancy than other energy sources.

FNC cells are perfect for long-life applications because there is no drop of power supply during operation and they can be put through more than 8000 part charge/discharge cycles. Also, the batteries can be charged without removal from the truck, with charging taking between 10 minutes and three hours, depending on the rating of the charger.

But it was lithium ion battery technology that generated so much interest at CeMat. Among the many benefits of these batteries is that they are light and small, maintenance free and never need to be refilled. Other benefits include longer life, zero degradation and higher capacity than any of the other technologies.

Also, lithium ion batteries have a much greater cycle life and a better weight to power ratio. But like the FNC batteries they have the ability to work at very low temperatures and they can be 'opportunity charged' very quickly. In fact their rapid recharge times are very similar rates to FNC batteries, eliminating the need to keep changing batteries or to use two batteries per shift which is usually the case with lead acid units.

To compare the three technologies, reduction in capacity of a lead acid battery, if discharged quickly over a 1hour period, is around 32%, whereas FNC offers between zero and 2% degradation while lithium ion batteries don't degrade at all. If an FNC battery was discharged to 50 per cent and recharged, it would offer around 8000 cycles compared to just 1500 with a lead acid battery. By contrast, a lithium ion battery could achieve up to 10,000 cycles.

And in terms of price, FNC batteries are around three times more expensive than lead acid while lithium ion are nine times dearer.

But considering all the excitement, why isn't the materials handling industry wholeheartedly embracing the light and small lithium ion batteries?

The answer lies in the question. The main benefit of lithium ion being lightweight and compact is that truck manufacturers will be able to design equipment that is radically different to what is currently in use. But until this happens having a smaller footprint and weighing less won't be of much benefit in existing trucks. This is because the batteries won't save any space on an existing forklift truck and they could even cause problems in terms of balancing a truck to keep it stable.

FNC still offers most of the benefits of lithium ion but without the expense – and the technology is available here and now.

This isn't to say that lithium ion technology won't have a bright future in the materials handling sector. But we predict that this will be some distance away yet.

Until then, current demand from the handling and storage industry for greater productivity and reliability will see FNC battery technology leading the way for the foreseeable long-term future.


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