from the dc bus lines 43 and 44 during power outages on ac power lines 48 with each of these types of systems the auxiliary power system 40 does not normally provide dc power on the lines 41 and 42 as long as proper ac power is provided from the lines 48 when extended power outages occur on the lines 48 the system 40 as described further below determines when an extended power outage has occurred or when the battery 45 cannot meet the demands of the load and turns on to provide the dc power in the lines 41 and 42 to take over the supply of power to the ups and thus supply power to the load the system of fig6 utilizes the auxiliary power supply 40 with a constant dc load such as a telecommunication system 50 which normally receives power from the dc bus lines 43 and 44 across which the battery 45 is connected when ac power is available from an ac power system on power lines 51 a charger 52 is operated to supply power on dc lines 53 to the bus lines 43 and 44 to maintain a charge on the battery 45 and supply power to the load 50 upon failure of the ac power system the auxiliary power system 40 is turned on to perform the duty of supplying charging power to the.