The ground station of our kite power system has been equipped with a new battery storage unit.
Over the last week our development team has been working hard to replace the old Lead-Calcium battery unit of our ground station with a brand-new Lithium-Iron-Phospate battery unit. This battery is used to store the energy that is produced by the kite power system and to supply energy for the reel-in phase and computers.
The old battery unit consisted of 27 Lead-Calcium batteries with a total capacity of 55 Ah. It needed replacement for two reasons. One was that the internal resistance of the battery unit was too high. Typically around 1 kW was lost while charging the unit. The second reason was that Lead-Acid batteries are generally not very good at absorbing currents of more than 20 Amps. The currents that the kite power system generates are over 50 Amps. This meant that about half of the energy that was generated was lost in the charging process. The new LiFePO4 battery has an internal resistance that is 3.5 times lower and can handle charge currents of up to 180 Amps. It goes without saying that this is a big step forward for us.