Boost to battery life

28 March 2017

Alongside its purchased equipment, the Hungarian subsidiary of forklift manufacturer Linde has a rental fleet comprising 1500 forklift trucks, 230 of which are for short-term use, at its site near Budapest. To ensure most of the electric-powered vehicles are ready for use, the dealer relies on technology from Fronius.

The charging system with four Fronius Switch Boxes, which Linde Hungary has been using since the start of the year, uses just four chargers to optimise the condition of 40 batteries, all with different voltages and capacities, and ensures the permanent availability of the fleet.

The trend of renting rather than buying is becoming increasingly popular in the intralogistics industry. For companies that do not need a forklift truck all the time or only need to meet a temporary increase in demand, buying is not cost-effective, making renting a significantly cheaper alternative.

Linde Hungary has responded to this trend and specialises in the rental of forklift trucks from its Budapest location, sited close to the motorway and around ten kilometres from the city centre. The company, which was founded in 1996, is a subsidiary of the Linde Group, whose corporate department Linde Material Handling is a world leading manufacturers of counterbalanced lift trucks and warehouse equipment. Linde Hungary generated a turnover of 18 million euros in 2015, and employs around 80 people. Their clients include national and international firms from all sectors of industry. To meet the high demand for forklift trucks, Linde has a fleet of around 1500 vehicles – 1200 for long-term lease and 230 for short-term hire. 1000 of these forklift trucks are electric powered and for this Linde Hungary uses more than 1500 24V, 48V and 80V batteries with various capacities. 

Maintenance of the 230 forklift trucks in the short-term rental fleet, which predominantly runs on batteries, is particularly demanding. "A real challenge for us is that the equipment has to work perfectly and be ready for use again as soon as possible, despite continually changing users," explains Tamás Sándor, MD of Linde Hungary. "We often have to get the equipment 100% ready for use and out to the next client within 24h." Before Linde Hungary can lease or sell on the used forklift trucks, the equipment is made ready in line with internal quality standards. In spite of this, they often experienced problems with their electric-powered vehicles in the past. "An important factor in terms of availability is the batteries. The main problem was that the charged batteries would often self-discharge when not in use. Not only was this bad for the batteries, it also delayed the entire process, sometimes by as much as a whole day", recounts Tamás Sándor. "In order to be sure that every client got a fully-charged battery, we had to recharge the batteries before every delivery." 

To solve this problem, Linde opted for innovative battery charging technology from specialists in this area Fronius. "We have worked with Fronius for a number of years and sell the Selectiva battery charging systems," explains Tamás Sándor about the partnership. At the beginning of February the technology leader, with headquarters in Pettenbach, Austria, installed a Switch Box system at Linde Hungary to charge the rental forklift truck batteries. This consists of four Fronius Switch Boxes, each of which is connected to a high-frequency Fronius battery charging system from the Selectiva 8090 range. Each box has several outputs that can charge up to ten batteries one after the other.

Selectiva battery charging systems automatically adjust to the condition, age and temperature of the battery using the innovative Ri charging process. Automatic voltage recognition allows the devices to flexibly charge batteries from 12 to 80 volts. The connected rechargeable batteries receive the precise amount of charge that they need and can no longer self-discharge before they are next used. Employees can programme the length of the charging cycle as desired. If a battery has charged up before the set time, the control system will automatically detect this and switch to the next battery. Once each battery has been charged in turn, the cycle is repeated until the batteries are removed. A particular advantage is that the extension cable allows the batteries to be charged not only in the installed unit, but also on the vehicle itself, saving on storage space in the factory.

"We developed the Fronius Switch Box specially for companies like Linde Hungary that have large rental fleets of electric-powered forklift trucks that they need to be able to supply around the clock," explains Markus Weinberger, Fronius Area Sales Manager for Eastern Europe and Scandinavia. Around 80% of Linde Hungary's 230 short-term rental forklift trucks are in use at any given time. This means an average of roughly 30 forklift trucks remain in the warehouse. "The four new Switch Boxes provide us with the capacity to charge a total of 40 batteries, which means we have enough space to charge all the rechargeable batteries in the factory before they are next needed. If one of our clients requests a rental vehicle, we can simply take the battery off the shelf and deliver the forklift truck straight away," summarises Tamás Sándor. The MD is also aware of another benefit of Fronius' innovative technology: "The new charging technology means one battery charging system can serve ten batteries simultaneously, regardless of voltage or capacity. All we need are the right charging plugs. This allows us to save on the costs associated with investment in additional devices." 

Minimising faults

Before Linde Hungary switched to Fronius' innovative technology, it had problems with faulty batteries. "Our batteries had a relatively short service life and would develop faults, which severely affected the availability of our rental fleet," explains Tamás Sándor. This was caused by long storage periods and overcharging. Not only did this increase the number of faults, it also reduced the service life of batteries, all of which impacted on customer satisfaction and significantly increased repair and purchasing costs. "With the Switch Box, which automatically switches to the next unit and preserves the charge of the rechargeable batteries, overcharging and the harmful sulphation that arises from self-discharge can be prevented. This prolongs the service life of the batteries significantly," emphasises Markus Weinberger. 

Not only did Fronius deliver the Switch Boxes to Linde Hungary, it installed the entire infrastructure. With the appropriate charging modules, adapters and safety devices, the specialist ensured that the new charging station complies with all current standards and regulations. Even the forklift truck dealer's employees benefit from the new technology. Operation, via an external display, is very user-friendly and self-explanatory. In the event of a battery malfunction during the charging process, a message appears on the display that has to be acknowledged by an employee, allowing faults to be detected before delivery to the client.

"Another problem was that we had no information as to the condition of the batteries," continues Tamás Sándor. To avoid delivering a relatively new forklift truck with an old battery that is not fully functional, Linde Hungary also uses a discharger in combination with the charging technology from Fronius. "We use this device to log the condition of the battery and to make informed decisions about continued use, repair or disposal."

"Since we started using the Switch Box system, the availability of our rental fleet has increased dramatically and the rental devices are now in tip top condition. From planning to installation, the partnership with Fronius has been flawless," summarises Tamás Sándor. "Fronius has fulfilled all of our requirements and we have already recommended the system to other Linde sites."