Clyde Space

Battery Lot Acceptance Testing

Every new batch of cells received by Clyde Space is subjected to a range of Lot Acceptance Tests, which are described below.   The test procedure was determined following extensive cell characterisation, balancing, and thermal testing, carried out in collaboration with ESA. 

Visual Inspection

 Cells are inspected visually for signs of shipping or other damage, any damaged cells are rejected.

Physical Measurements

All cells are marked, and measured for length, width and height, as well as weight. 

Electrical Measurements

Open circuit voltage readings are made on all cells

Destructive Parts Analysis (DPA) 

A sample of cells undergo DPA to verify the cell structure.  The cells are cut at the bottom, and the outer packaging carefully removed.  The components are separated, and examined visually and dimensionally for any changes in structure, or materials. 

Standard Capacity Measurement

A sample of cells are subjected to a standard capacity measurement.  The cells are charged with a constant current to 4.2V at a C/5 rate, and then discharged to 3V, also at a C/5 rate. 

Capacity at Various Temperatures and Rates

The capacity of a sample of cells is measured at a C/15 rate at temperatures of 20°C, 0°C, and -20°C.  Capacities are also measured at a C/2 rate, at 20°C, and 0°C. 

Vacuum Cycling

Vacuum cycling, at 19mbar, is performed at room temperature on a sample of cells.  Ten cycles are performed at a C/2 rate, and capacities measured before, during, and after testing.