Self-cooling batteries: more power for large electric forklift trucks

In heavy-duty applications, such as in the paper industry, the conventional lead acid batteries of large electric forklift trucks often reach their temperature limits. With self-cooling PowerPlusLife batteries, the renowned forklift truck manufacturer and intralogistics specialist STILL has developed a costeffective solution. Lünewell, the corrugated board manufacturer, is already reaping the benefits. Two STILL RX 60 electric forklift trucks (8-tonne load capacity) were fitted with the patented battery system to meet the demands of handling up to 3.8-tonne paper rolls.

Lünewell: “The art of corrugation”

The medium-sized family business Cartoflex has been converting corrugated
board into intelligent packaging systems for 35 years. In its new production hall in
Lüneberg, its subsidiary company Lünewell now produces more than 150 million
square metres of its own corrugated board per year using cutting-edge technology. It
is now applying its specialist knowledge of the packaging industry’s specific requirements
for the corrugated profile, acquired over many years, to its own corrugated
board production.

Handling heavy paper rolls with electric forklift trucks

Thirty STILL electric industrial trucks are used to transport the delicate products.
The full service means they are always available and the costs easy to calculate.
Lorries deliver some 72 paper rolls to the production hall every day. The magnificent
rolls weigh up to 3.8 tonnes and stand 2.5 metres high. Two new RX 60-80 electric
forklift trucks were purchased from STILL specifically to cope with the challenge of
handling the heavy rolls; they were each fitted with one of STILL’s air-cooled Power-
PlusLife batteries for high handling capacity. The powerful RX 60 forklift trucks are
able to unload the lorries and transport the products to the warehouse, where up to
three paper rolls are stacked up to a total height of 7.5 metres to save space. They
also feed the paper rolls into the production machine.

Electric forklift trucks versus forklift trucks with combustion engines

Until now, diesel trucks, in particular, have offered high load capacities. The engines
often had to be fitted with additional components such as diesel catalytic converters,
particle filters and SCR (selective catalytic reduction) catalysts to reduce nitrogen
oxide emissions (NOX) for indoor use. Andreas Isermann, Head of Maintenance,
confirms this, adding: “In addition to the strict requirements and contaminated air,
which would have soiled the paper rolls, we would have had to install a tank system.

Diesel trucks are also louder than equivalent electric ones and increase the room
temperature, which is already high from the corrugated card production.”
Electromobility is gaining more and more momentum – electrical energy storage
systems are becoming increasingly efficient, and volume effects are sure to bring
about a reduction in prices in the future. The costs of servicing and maintaining electric
forklift trucks are considerably lower than for equivalent diesel trucks. With the
increasing efficiency of the energy storage systems, more powerful components are
also being installed. Consequently, electric vehicles, which are more efficient than
ones with fossil fuel drives, will increasingly encroach on the domains of vehicles
with internal combustion engines.

PowerPlusLife battery technology

In heavy-duty electric forklift truck applications, that is, ones which consume a lot of
power such as the handling of heavy paper rolls, the core temperature of lead acid
batteries can get too high. Until now, the only solution was to install additional or
particularly expensive specialist batteries with a high energy density.
In contrast, STILL’s PowerPlusLife battery draws on tried and tested lead acid
technology and offers a cost-effective solution thanks to its patented self-cooling
system. In the new STILL PowerPlusLife battery, a number of temperature-controlled
fans cool the battery’s core effectively in any situation. The air cooling system lowers
the temperature of the battery in the forklift truck, at the charger or at the point of supply. That eliminates the need for cooling cycles after driving and loading. Andreas
Isermann: “STILL’s battery technology came just at the right time. We now have
enough capacity for a full shift. After that, the batteries can be recharged quickly.
Additional replacement batteries are no longer necessary.”

The electric forklift truck’s power enters the domain of the IC truck

The reduction of the core temperature by up to 20°C significantly conserves STILL’s
PowerPlusLife battery. That drastically increases capacity. The acceleration and
lifting speed, for example, can be increased by up to 25 percent. If necessary, the
maximum driving speed can be increased by 18 percent from 17 to 20 km/h.
STILL’s 8-tonne electric forklift trucks in the RX 60-80 series therefore have a
comparable load capacity, until now reserved only for powerful forklift trucks with
combustion engines!

Andreas Isermann emphasises: “The reduction of the forklift truck battery’s core
temperature is the crucial factor. In STILL’s PowerPlusLife battery, cooling prevents
a loss of capacity. Lowering the temperatures also reduces the physical load. The
batteries therefore do not need to be changed as often. Together with the fast lateral
battery change and the manoeuvrability of the RX 60-80, the bottom line is an
increase in load capacity.”

Longer service life, fewer replacement batteries

The reduction in the operating temperature of the STILL PowerPlusLife battery
increases service life by up to two years, even in the most heavy-duty applications.
“The elimination of long cooling cycles means we only need two replacement batteries
for both RX 60-80 trucks as opposed to five. So there is much less strain on both
our batteries and budget,” sums up the satisfied head of maintenance.