External Hardware

Solar Panels

There are five P110 solar panels from Gomspace and one Top solar panel from ISIS. Each solar panel is composed of two Azur Space 3G30A solar cells connected in series. The solar panels are connected two-by-two in parallel. The electrical characteristics for full sunlight in LEO are as follows:

Parameter	Condition	Min	Typical	Max	Unit
Voltage	Optimal Voltage	4.64		4.84	V
Current	Current at Optimal Voltage	490		508	mA
Power	Maximum Power	2270		2400	mW
Efficiency		29.8	30	30.2	%

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Batteries Board

The FloripaSat batteries are not on the EPS PCB due to size restrictions. An auxiliary PCB contains the batteries and it is connected to the the EPS PCB using a power header. The Batteries, ICR18650-30B, are two lithium-ion connected in series that supply up to 22.2 Wh. The electrical characteristics are displayed in the Table below.

Parameter	Value	Unit
Nominal Capacity	2950	mAh
Nominal Voltage	3.78	V
Charging Voltage	4.35	V
Standard Charging Current	1475	mA
Max. Charging Current	2950	mA
Max. Discharging Current	5900	mA
Discharge cut-off Voltage	2.75	V
Operating Temperature	0-45	ºC

The batteries are fixed in the batteries PCB by a 18650 battery holder. Also, a mechanical holder is placed over the batteries and screwed to the board. One heater is placed around each battery.

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Batteries Charger

The EPS subsystem has an external batteries charger to recharge the batteries before the flight. The board uses a BQ2057wsn chip that controls the batteries charging procedure. The External Batteries Charger PCB shall be connected to the EPS PCB using wires in the headers. The Table below shows the charger parameters and procedure to perform batteries charging through this PCB.

Parameter	Min	Typical	Max	Unit
Vcc	4.5		15	V
Vo	8.317	8.4	8.484	V
Vsns	113.6	125	137.5	mV
Ireg	1.385	1.52	1.677	A
Iterm	293	170	48	mA

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