Backup Power

Status: In operations

Night VFR certification requires backup power source for some instruments.

In order to comply with the requirement the CAN HUB board has been modified to accommodate additional battery charge circuit.

With three 3000mAh 18650 batteries the unit provides 2 hours of power (about 30W*Hrs) to all avionics onboard excluding radios and the transponder.

Backup Battery Charge Controller

Essentially CAH_HUB ver 3 is the same as CAN _HUB ver 2 with a battery charge controller between the switch-mode power converter and the input power.

Charge controller is based on MP26123 chip from Monolithic Power (MP26123 Datasheet). It is reasonably priced, readily available and provides sufficient control over safe charging for three 18650 Lithium-Ion batteries.

Key features and controls:

• The unit is configured to charge at initial current not above 1.3 A  (R3=150 mOhm).
• Charging process will stop if the battery temperature goes outside of a safe range  (0C – 50C).
• Charging will also stop if it runs for more than 3 hours (indication of faulty battery).
• Fully discharged battery will be trickle-charged with charge current of about 130mA until the batteries reach level of 3V per element.
• The unit has 4 output ports for monitoring the charger and the battery status. The ports are monitored by Module-A (see Module-A page for details).

Connecting the CAN HUB unit to the rest of the aircraft electric circuit.

Same image in PDF format: CAN_HUB_3_Interconnection.pdf

Battery Unit