Performance of INTELSAT V Ni-H2 Batteries in Orbit (1983-1991) 929090

The INTELSAT V Spacecraft F-6 (launched in 1983) was the first geosynchronous earth orbit (GEO) satellite to use Ni-H₂ batteries. Since then, seven more of these INTELSAT V satellites (F-7, F-8, F-10, F-11, F-12, F-13, and F-15) have been successfully launched with Ni-H₂ batteries. The last one, F-15, was launched in the spring of 1989. Two 27-cell 30-Ah batteries are used on each INTELSAT V spacecraft. A description of these batteries is presented, including the cell design features and the mechanical, thermal, and electrical design features of the battery. The batteries in the first six spacecraft are discharged to 56 percent depth-of-discharge (DOD) during eclipse periods, and the batteries in the last two spacecraft to 67 percent DOD. Performance data are presented for these batteries from the time they were launched through the Fall eclipse season 1991. These data include (1) the battery minimum end-of-discharge (EOD) voltage observed during each eclipse season and the minimum individual cell voltage within each battery; (2) the reconditioning capacity measured prior to each eclipse season; and (3) the end-of-charge (EOC) and the end-of-discharge (EOD) pressure measured during each reconditioning cycle. Data are presented for the 14 batteries on F-6, F-8, F-10, F-11, F-12, F-13, and F-15 spacescraft. The reconditioning capacity for these 14 batteries in orbit has become stable with time, and the capacities are closely matched. The range in capacity for all 14 batteries was between 38.3 and 43.4 Ah for the Fall 1992 reconditioning. There has been no increase in the reconditioning EOD pressure after eight years of operation. The average EOD pressure for all 14 batteries in the Fall of 1990 was 32.3 psi, as compared with 31.7 psi average at the beginning of life. These data show that there is no oxidation (plaque corrosion) occuring within these cells. The EOD voltage is stable with time during eclipse operations. It is difficult to predict the lifetime of these INTELSAT V Ni-H₂ batteries because they show very little voltage loss after 8 years in orbit. The expectation now is that these batteries will last beyond 15 years in orbit.