Press release
Fronius unveils innovative Ri charging process with highest levels of energy efficiency
New battery charging system saves electricity and reduces CO2
(Wels, Austria) Fronius, the Austrian battery charging system specialist, has developed a generation
of battery charging systems for traction batteries that is both a world first and totally in keeping with
today's requirements: resource-conserving and cost-effective. In addition to a much longer battery
service life, one of the most impressive features of the new Ri charging process is its maximum
energy efficiency.
It's unfortunately a fact: more than half of all the battery charging systems used in Europe to charge forklift
truck batteries still rely on the old 50 Hz transformer technology. The efficiency levels of such systems are,
by today's standards, frighteningly low. The power loss means that device efficiency hovers around the 80
percent mark. And the charging efficiency, at just 70 percent, is even lower. Bringing both together gives a
total efficiency figure of about 56 percent. Or, to put it another way, of all the energy drawn from the socket,
an average of 44 percent, almost half, is lost when the vehicle battery is fully charged. And in times when
everyone is increasingly trying to conserve resources, such wastage is hardly justifiable.
A step in the right direction – albeit a small one – was taken with the introduction of battery charging systems
employing inverter or HF technology for traction batteries. This technology boasts a certain amount of
intelligence, checks the battery and monitors the charging process from start to finish. But with a total
efficiency of approximately 68 percent, these battery charging systems still consume comparatively large
amounts of electricity. The reasons for this are the high charging losses at the start of the charging process
and the overcharging at the end.
A more significant change of tack towards greater efficiency was the development by Fronius, the Austrian
battery charging system specialist, of “Selectiva” battery charging systems with “Active Inverter Technology”
for intralogistics applications. This high-frequency based technology returns a total efficiency figure of around
74 percent. Proven in the field since 2005, it delivers significant savings in energy costs and results in less
maintenance of the batteries while extending their service life. The small footprint of the system frees up
valuable storage space and the technology helps the environment by dramatically reducing CO 2 emissions.
All in all, the Total Cost of Ownership (TCO) is significantly lower.
Real customer benefit as a result of reduced power requirements
During times when intralogistics represents a growing cost factor in many businesses, a trend towards
greater efficiency is becoming increasingly apparent. In addition, fresh requirements are emerging from
within the logistics chain, the topic of sustainability being a good example. In many cases, it is precisely
energy costs that make up such a large proportion of the overall costs. To reduce these costs even further,
the Fronius specialists have developed a new generation of “Selectiva” systems with three-phase
connections for the 24, 48 and 80 Volt traction batteries typically found in electric stackers, narrow-aisle
stackers and electro-tractors. The new systems – distinguishable by their fresh black and red design – were
unveiled to the public at the LogiMAT 2013 show in Stuttgart. They impress with their maximum energy
efficiency, maximum battery service life and maximum levels of safety and, with the new, groundbreaking Ri
charging process introduced by Fronius, will change the battery charging system landscape for ever.
As batteries are being charged and discharged, the effective inner resistance of the cells (Ri) causes heat to
be released. This results in the loss of some of the energy used in the charging process. The relationship
between the amount of energy available from the battery to the energy applied during charging is referred to
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as the charging efficiency. In other words, the lower the charging losses, the higher the charging efficiency.
This is where the Fronius specialists came in. They complained that the charge losses were being caused by
predefined charging characteristics in which a preset, and sometimes too high, charging current was applied
to the battery at the start of the charging process, regardless of the state of charge of the battery. To alter
this state of affairs, the Austrian engineers came up with the Ri charging process with its own characteristic.
The Ri charging process – a stroke of genius from Fronius
The effective inner resistance of the battery “Ri” is a battery-specific value that changes during charging and
discharging due to fluctuating acid concentrations and parasitic effects, such as diffusion processes,
polarisation-overvoltage or the conversion of lead sulphate into lead oxide. The really special feature of the
unique Ri characteristic is that the charging voltage is determined by measuring the effective inner
resistance. This ensures that the charging current adapts automatically to remain in line with the effective
inner resistance curve of the battery. Hence, if the effective inner resistance rises such that the current-input
capability of the battery is lower than when charging began, then the charging current will be lower and
charge losses avoided. Should the effective inner resistance drop during charging (current-input capability
increases), the charging current is increased automatically so that it can be reduced later during the charging
process, again as a function of the increasing effective inner resistance, since the battery will now be fully
charged and its current-input capability correspondingly lower. This means that every charging cycle for
every battery is a one-off with its own individual characteristic.
To enable the battery charging system to specify the starting value and the ongoing progression of the
charging voltage, the current battery state of charge is continually recorded. During this process, the type of
battery in question, how old it is, its temperature and discharge level are all monitored. The battery charging
system software then uses this battery information to modify the individual charging phases by keeping the
voltage curve constant and regulating the charging current in line with the effective inner resistance curve.
The Ri charging process from Fronius is therefore a self-regulating process – a true stroke of genius. The
charge losses at the start of charging shrink to a minimum due to the lower power requirement. The
consequences: a saving in energy and only insignificant warming of the battery. There is hardly any
overcharging at the end of charging, as the current drops.
Thanks to the individual Ri charging characteristic, the newly developed “Selectiva” devices achieve charging
efficiency levels that were previously inconceivable: a staggering 90 percent. Combining this with device
efficiency, which Fronius has been able to increase to 93 percent by commercially acceptable means, results
in a total efficiency value of 84 percent – a figure that has never been attained before.
Particularly energy efficient is the fact that one only has to specify the battery voltage and the charging time,
as in reality many batteries that are connected to the battery charging system tend to be only partially
discharged. By specifying a charging time, however, the charging process can be extended over the whole
period. This enables the battery to be charged very gently due to the lower energy input and the
correspondingly lower warming effect. For companies with fluctuating forklift truck utilisation levels, harmful
overcharging is prevented and the precious batteries remain undamaged. Furthermore, peak currents are
prevented in situations where the charging of a number of forklift truck batteries starts simultaneously at the
end of a shift. Peak currents are to be avoided, as they drive up costs.
Enhancements that shift the limits
Achieving maximum battery service life is only one of the many features that make the new generation of Ri
characteristic devices from Fronius so attractive. The new devices boast many other enhancements that
supplement the outstanding features already present in the existing “Selectiva” range. A few key facts: the
largest variant (80 V with 180 A) now weighs only 30 kg instead of 40 kg and is smaller in size. The
ventilation system has also been reworked. It now reduces contamination inside the battery charging system
even further. The focus for the Fronius developers was to significantly improve safety, user-friendliness,
service and system monitoring. Our highly trained employees in the Fronius Sales and Service network will
be able to tell you about other energy-saving and trail-blazing features of the “Selectiva” series with the Ri
characteristic.
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For more information, see: Ri charging process: www.fronius.com/ri-ladeprozess
Photo 1
The new generation of “Selectiva” battery charging systems with the
innovative Ri characteristic sets new standards in terms of energy efficiency
and battery service. life
(Photo: Fronius)
Image file: Fronius_Selectiva_Ri_Energieeffizienz_01.jpg
Photo 2
In each phase of the Ri charging process, the battery only receives the
energy that it can actually absorb during that phase. Maximum energy
efficiency levels are achieved as a result.
(Photo: Fronius)
Image file: Fronius_Selectiva_Ri_Energieeffizienz_02.jpg
Photo 3
As battery charging consists of two sequential processes, logistics decisionmakers need to consider the total efficiency figure.
(Photo: Fronius)
Image file: Fronius_Selectiva_Ri_Energieeffizienz_03.jpg
Copyright to photos: Fronius International GmbH, reproduction free of charge
About Fronius International GmbH
Fronius International GmbH is an Austrian company with headquarters in Pettenbach and other sites in Wels,
Thalheim, Steinhaus and Sattledt. With 3,239 employees worldwide, the company is active in the fields of
battery charging systems, welding technology and solar electronics. Around 93% of its products are exported
through 19 international Fronius subsidiaries and sales partners/representatives in over 60 countries. With its
innovative products and services and 864 active patents, Fronius is a global technology leader.
Fronius International GmbH
Enquiries: Boris Ringwald, +43 664 602416436, ringwald.boris@fronius.com
Copies: Boris Ringwald, Froniusplatz 1, 4600 Wels, Austria
Fronius U.K. Limited
Enquiries: Ross Adams, +44 7580 076988, adams.ross@fronius.com
Copies: Ross Adams, Maidstone Road, Kingston, Milton Keynes, MK10 0BD United Kingdom
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