The supply of electrical power is one of the most important functions required by the diverse payloads of satellites. A fault in the corresponding subsystem might lead to mission or even vehicle loss. Among the causes of such faults, we highlight the phenomenon of thermal avalanche in batteries. It can be explained as an energetic unbalance where the rate of heat generated in the interior of the system exceeds its capacity to dissipate it. This occurred to the OAO1 of NASA just after its launch on April 8, 1966; and with the CBERS2 of CAST and INPE already in orbit in 2007 and 2009. This work presents a discussion on the causes and effects of thermal avalanches in artificial satellite battery charging and discharging systems. To do so it: 1) revises the literature on the known causes and effects; 2) develops a block diagram model for a battery charging and discharging system in artificial satellites, based on macroscopic principles which can be generalized to a wide variety of topologies and technologies of power supply and batteries; 3) discusses new causes and effects. Such discussion allows: 1) explains the thermal avalanche occurred to OAO1 and CBERS2; 2) estimate whether this will occur or not to other similar satellites as the CBERS3&4.