Strategy for maintaining state of charge of a low-voltage battery bank in a hybrid electric vehicle having a high-voltage traction battery bank

摘要

A hybrid electric motor vehicle (12) has a combustion engine (14), a high-voltage battery bank (28), a low-voltage battery bank (30), an electric generator (32) driven by engine (14) for recharging battery bank (30), a DC-to-DC converter (46) for recharging battery bank (30) from battery bank (28), a monitor for indicating voltage of battery bank (30), a recharge initiate timer that, while battery bank (28) and not generator (32) is recharging battery bank (30) via converter (46), is started by the monitor indicating that voltage of battery bank (30) is below a recharge initiate threshold and whose rate of timing is a function of voltage indicated by the monitor as the timer times. If the timer times to a recharge initiate limit, the generator begins recharging battery bank (30).