System summary
The BECA project is a sealed lead-acid battery, to be used as a backup battery for aircraft avionics system. The battery is made to fit into a ARINC 404 ¼ ATR tray, and uses DPXB-13-34B connector. The connector is customizable according to customer needs.
On the front part, the battery has a DB-25 connector used for maintenance and storage purposes. The front also has a test button to run functional checks during on wing maintenance, and a circuit breaker to protect the battery output.
The battery is made according to Technical Standard Order (TSO) number C173-a. This TSO lists, among other requirements, DO-293A for functional and environmental qualification and DO-254 for electronic hardware qualification.
The MTBF of the battery electronics is above 50.000 hours, making cell replacement cost-effective.
Functional summary
The backup battery main function is to provide emergency energy for any electrical subsystem. To achieve this function properly and safely, the battery is developed with an internal heater and a power bypass to allow energy to freely flow from the input to the output if needed. Protections are built to increase battery reliability and Built-In-Tests are also developed to help during maintenance.
The battery functional envelope, with estimated values for total useful discharge time at 120 W is shown in the graph from 100% and 72% SoC to the end point voltage (19.5 V). The cold degradation starts at -20 ºC. The battery heater can create a 25 ºC difference to the environment. The overtemperature protection triggers at 55 ºC.
The battery ON BIT considers that the battery turns on when more than 350 mA is passing through the output. The maximum current is 15 A, protected by an output circuit breaker.
