The Arcus E is equipped with a battery-system utilizing Li-Ion cells of the type SAFT VL41M. Lange Aviation was worldwide the first manufacturer to utilize these cells, but meanwhile an impressive array of other users have recognized the advantages of this cell, and its field of application is constantly broadening.
Lithium is the lightest of all metals, and has the highest negative standard potential. The low weight and high voltage level of the system result in a high specific energy density. Compared to other currently available Lithium based cells (Li-Po / Li-Su), SAFT VL41M exhibits very high current capability and very good cycleability. This qualifies SAFT VL41M Li-Ion cells for application as aircraft energy storage before all other available cells.
Performance
A full charge will deliver the Arcus E up to 3100m above its starting point (See technical data for more details). It is off course possible to divide the available energy into one or more takeoffs and climbs. An extra takeoff costs approximately 100m climb altitude.
As with all batteries, the performance of Li-ion batteries is affected by the battery temperature. To counter this effect, the battery-packs are equipped with electrical battery heating. If the battery charger is connected to the power grid, then the energy required to heat the batteries can be provided by the battery-charger. In the air, the battery modules use their own energy to maintain optimal battery temperature. This process happens automatically. It is possible to turn the heating off and on in flight in order to conserve energy during very long flights. With the battery heating turned off, the good isolating properties of the wing ensures that it takes a long time for the batteries to cool down to a temperature where the performance of the battery is affected.
Battery life
The life expectancy of the Arcus E drive battery is determined by two factors:
- the number of charge/discharge cycles
- the natural chemical aging
Charge / discharge cycles
The capacity of a battery diminishes with the number of charge-discharge cycles it undergoes. According to the latest knowledge, the battery will withstand more than 3000 SAE cycles. One SAE cycle consists of a full charge, and a discharge down to 20% of battery capacity. A partial charge and discharge equals a partial full cycle. After 3000 SAE cycles, the cells will retain at least 80% of their original capacity. For the pilot, this means that the drive battery will yield approximately 4.150.000 m (13.615.000 ft) climb altitude before it should be replaced.
Natural aging
More relevant to the practical application is the natural chemical aging of the battery. If the battery is stored at an average temperature of 20°C (68°F), then it is advised to change the battery after 20 years. At this point the battery will have a remaining capacity of 80% of the original capacity.
Availability
As a user of SAFT VL41M cells, Lange Aviation is in good company. SAFT VL41M are also used in most new European satellites, the RQ-4B Global Hawk UAV, the F35 Joint Strike Fighter, the Airbus A380 and in many other high-tech applications.
Next to being a great vote of confidence to SAFT VL41M cells, the military implementations mean that the cells which are now being built into the Antares 20E will be available at least until 2031.
Battery location
The two battery packs are positioned in the leading edges of both inner wings. The battery packs are installed and removal through an opening in the wing root rib. These jobs each take only 20 minutes to perform.
Since the addition of batteries to the wing results in increased weight, the Arcus E will come standard with a modified version of the popular Antares rigging aid.
The rigging aid, reduces the effort and rigging time to a minimum. One person can rig the aircraft alone, but as always, being two people makes things slightly more pleasant and convenient.