Saving time, power and water
01 October 2016
Daimler Mercedes–Benz in Bremen has switched to EnerSys NexSys TPPL (Thin Plate Pure Lead) technology batteries for their fast charging, opportunity charging and zero battery change capabilities
The NexSys range is suitable for an extensive range of vehicles including lift trucks, order pickers, pallet trucks, Automated Guided Vehicles /Laser Guided Vehicles and cleaning machines.
Mercedes Benz in Bremen is the second largest Mercedes automotive factory in Europe and produces more than 300,000 vehicles per year. Recently the company built a new production hall. The aim was to reduce the number of battery changes for its forklift fleet and to close the charging rooms in favour of decentralised charging near the production line. This posed a challenge however, as charging gases and acid aerosols cannot be allowed to contaminate the vehicle production environment, which meant traditional flooded batteries couldn’t be used.
The emergence of a new type of lead-acid battery using TPPL technology offers a practical, affordable and environmentally friendly alternative to conventional batteries and Lithium-ion designs. EnerSys says it offers significant operational benefits such as the ability to charge repeatedly from any depth of discharge (up to 80%) without affecting the condition of the battery. Moreover the increased reliability and elimination of water loss ensures that TPPL batteries are low maintenance and cost-effective.
EnerSys offered the solution with its NexSys TPPL batteries with absorbed electrolyte as a virtually maintenance-free technology. As they are completely sealed, the creation of oxyhydrogen is minimised and the formation of acid aerosols is completely eliminated.
TPPL builds on the proven capabilities of traditional lead-acid batteries with some significant technological advances. In traditional lead-acid designs the positive and negative plates are typically over 4mm thick but with TPPL they are thinner, circa 1mm. More TPPL plates can therefore be fitted in any given size of enclosure which in turn increases the total surface area available, providing inherently higher volumetric and gravimetric energy and power density than conventional units of the same size.
The other significant difference with TPPL, says EnerSys, is that the conductive grid is manufactured using lead that is much purer (typically 99.99% pure) than in conventional designs. This purity results in significantly reduced side reactions within the electrochemistry, which leads to improvements in charge acceptance and cyclic capabilities of the batteries. It also ensures the plates are much less likely to corrode and have longer shelf-life while extremely high recombination levels ensure water losses during recharge are minimised to provide optimum life.
A major advantage of this advanced technology is that the need to exchange a battery with a fully charged replacement at the end of the shift can often be eliminated. Christian Wessolowski, sales area manager at EnerSys Motive Power, pointed out: “In automotive manufacturing there is always the problem that batteries must be changed. This takes time and it is potentially dangerous, posing risk of injury to the operator."
Instead, the TPPL battery can be recharged for short periods whenever there is an opportunity, such as when an operative is on a break or completing some task away from their vehicle. Wessolowski continues: “We have on one side the power of a conventional flooded lead acid battery, on the other side, the reduced maintenance of a gel battery, used in a multiple shift operation. All this comes associated with a rapid charging system, which brings the batteries back to full charge within the shortest time. By switching to the new battery technology, more than 24,000 battery changes at Daimler can be saved per year.”
In addition to being cost-efficient, safer and virtually maintenance-free, NexSys batteries are environmentally friendly. Up to 90% of the materials used in lead-acid batteries can be recycled. As Daimler found out, choosing TPPL technology resulted also in saving 21,750 litres of water, and 247,500kwH of electricity.