Amprius Technologies SiCore SA08 High Power Pouch Cell

The Amprius SiCore SA08 is a high-power silicon-anode pouch cell from Amprius Technologies of Fremont, California. It is intended for medium multicopters. Unlike a fixed-wing aircraft in cruise, such drones draw high current continuously in the hover, so the cell needs more current capability than a pure endurance cell.

At 11,000 mAh the manufacturer specifies continuous discharge of up to 5C. That gives 55 A, a value calculated from C-rate and capacity. The price of the high current is energy density: 345 Wh/kg stays below what pure energy cells with a silicon anode reach, because current capability and energy density can only be traded against each other in one cell. The cell measures 144.5 × 52.0 mm in length and width, and the cycle figure is 250.

In a pack several cells are connected in series, and the same current flows through every cell in a series string, so the 55 A applies to the whole pack. At this load, cell connectors and protection electronics help decide the usable power, so assembly belongs in a specialist workshop with test and protection equipment. For transport, UN 38.3 requires proof of testing, and for air travel the IATA limits of 100 and 160 Wh apply to spare batteries.

When choosing, the motors' hover current matters: it should stay well below 55 A so that reserve remains for manoeuvres. 250 cycles are few; with one flight a day they are used up in less than a year. Heat in the fuselage and continuous load at the limit shorten life further; the pouch format is sensitive to pressure and needs room to expand.