Battery System Requirements
Coastal Profiling Float Primary Battery System

2021-07-26	ECM	adapt from HD Battery req'ts doc

1.	Physical

1.1.	Battery pack, plus battery control circuits, should fit into designated annular volume within Float pressure housing.  Dimensions are approx 2.7” ID x 8.0” OD x 9.2” OAL, with ability to be installed and removed radially (i.e. 2.7” clearance).

1.2.	Ambient temperature limits are 0-50 degC.  Most discharge will take place around 10 degC.

1.3.	Pack plus control circuits should tolerate normal shipboard oceanographic environment:  TBD any axis shock, 20-99% RH, and filtered salt air. 

2.	Electrical

2.1.	Battery system actual energy capacity will be determined by the designated volume.  Desired capacity is ~3.2 kWh at 20 degC.  It is expected that the available volume will accommodate an 8S4P arrangement of DD cells, plus monitor and control circuits.

2.2.	Battery system output bus voltage should be 20-32 V continuous, 24 V nominal, 42 V absolute max.  It is expected this will allow an 8S lithium primary architecture.

2.3.	Battery system max discharge current is 11 A.  Wiring and fusing should support this load.

2.4.	Typical daily discharge profile is 10 min pumping at 8 A, 1 hr profiling at 0.3 A, and ~23 hr sleeping at 0.004 A.

2.6.	Battery system internal consumption should be less than 5% per year, not including cell self-discharge.  This implies standby power during Sleep (see Features, below) less than 10 mW.

2.8.	Battery pack discharge current should be integrated by the control circuits, with TBD time resolution and measurement accuracy, to yield total pack charge (coulomb count) in real time, to TBD resolution.

3.	Interfaces to Float system

3.1.	Connection to Motherboard (CPF Microcontroller):  The battery system should present I2C on two signal lines at 100 kbit/s, 24 V battery power output at 3.2 A max, and I2C 5 V logic power input at 100 mA max (for Mobo-related interface circuits in the battery pack)..  It is expected that the I2C connection will provide CPF Micro access to the battery system fuel gauges, pump power controls, and sleep timer.  A Harwin M80-5100842 connector is desired for compatibility.

3.2.	Connection to Pump Drive: the battery system should present 24V battery power at 8 A max.  A Harwin M80-5000000M3-04-332-00-000 connector is desired for compatibility.

4.	Features

4.2.	Battery system should include sleep timer logic able to switch the system outputs off for programmable periods from 1 to 64 minutes.   The sleep function should be armed and triggered over the I2C connection to the Mobo/Micro.  (Existing LHE functionality.)  Standby power in the sleep state should be less than 10 mW.

4.3.	Battery system outputs should be switched on/off from the endcap by two momentary contact reed switches.  (Existing LHE functionality.)  Power when switched off should be less than 10 mW.

4.4.	Battery system should include power switching, fault reporting, and energy monitoring for the Pump Drive power output.  The power, fault, and monitor functions should be controlled over the I2C connection to the Mobo/Micro.  (Existing LHE functionality.)

4.4.1.	Pump Drive power switch should include soft start inrush control with a current limit of 10A and be able to charge 1000 uF of downstream capacitance.
4.4.2.	Pump Drive power switch should include Electronic Circuit Breaker function with a trip rating of 10A and trip time of 15 msec.
4.4.3.	Pump Drive power feed should use a large TVS diode(s) for pump regen control.  An active regen control circuit is not required.
4.4.4.	Pump Drive power feed should include an energy monitor circuit.  The energy data should be accessible to the Mobo/Micro over the I2C bus.  The LTC2946 device is desired for compatibility.
4.4.5.	Pump Drive power switch should include a watchdog with TBD functionality.

5.	Safety

5.1		The pack should be supplied by the manufacturer with cell shunt diodes, series string diodes, and fuses, as required to ensure safe operation while meeting the discharge requirements specified in Section 2 above.

6.   Battery Pack Requirements (for cell manufacturer and pack integrator), abstracted from above:

6.1  Pack must operate safely over the range 0-50 degC.   If possible, performance should be characterized at 10 degC.

6.2  Assembled pack must tolerate normal shipboard oceanographic environment:  TBD any axis shock/vibration, 20-99% RH, and filtered salt air. 

6.3 Output voltage should be 36 V max, 20 V min, at 8 A discharge rate.

6.4 Max discharge current (for wiring and fusing) will be 11 A.  The typical discharge profile will be 10 min at 8 A, 1 hr at 0.3 A, and ~6 hr sleeping at <0.004 A.