[Float and Float cum Boost charger – Single Battery – Single load]
The Battery Charging equipment comprises of Float charger & Float cum Boost charger.
Float charger has only Constant Voltage mode. It is capable to supply trickle charging current to battery as well as supply the station load.
Float cum Boost charger has two modes of operation i) Constant Voltage Float Mode, ii) Constant Voltage / Current Boost Mode (as applicable as per the battery type).
Normally, Float charger will supply the trickle charging current required for the batteries and will also feed the DC continuous load as required. During this time, the float charger and the battery are across the DC load terminals. If float charger fails, the float cum boost charger will operate in float mode either Manually or Automatically depending upon the circuitry logic provided in charger as per customer specification.
During an emergency when AC power fails, the battery supplies the load and discharges to certain extent depending upon duration of emergency and the intensity of the discharge current. When AC power is restored, the battery needs to be boost charged for which operate Float cum Boost charger in its boost mode.
When there is a power failure, the battery readily meets the DC loads. When power resumes, the battery has to be recharged for which operate the Float cum Boost charger in Boost mode either Manually or Automatically depending upon the circuitry logic provided in charger as per customer specification. During this period of boost charging, the DC contactor will gets open, thus higher voltage during boost charging will not appear across the load and the load will be supplied through Float charger.
In this scheme of Battery Charger, the use of Float charger for boost charging of battery is not possible in case of failure of Float cum Boost Charger.
To overcome on the above, next scheme is Dual Float cum Boost charger – Single Battery – Single load.