Standby & Cyclic definitions

Standby and Cyclic definitions for industrial VRLA battery applications.


A float STANDBY application is one where a battery is maintained, using a float charge voltage, in a 100% state of charge ready to support an attached load immediately should the mains supply fail. The float charge voltage ensures the correct current flow to compensate for any self-discharge characteristic1.  A typical application for an industrial battery system would be an Uninterruptable Power Supply (UPS).

Yuasa consider a float STANDBY application to be where a battery

Has no more discharges than is indicated on table below

DOD ² Allowable Discharges per Year (average)
0.1 – 10% 16-18
11- 30% 10-12
31- 100% 2-3
  • Is expected to have prolonged periods of float charge, > 3months, between discharges on average and at least 72 hours recharge between planned consecutive discharges (unless the battery you are using has repeat duty sizing for reduced charging times).
  • Is expected to spend >99.9% of its life on float charge.
  • Is never left in partially discharged condition.

Yuasa VRLA STANDBY Battery types: NP, NPL, SWL and EN


A CYCLIC application is one where a battery is discharged and charged on a regular and/or planned basis. A typical application for a CYCLIC industrial battery system would be an electrical power load shedding system.

Yuasa consider a CYCLIC application to be where a battery

  • Is regularly3 subjected to charge times of <72 hours between discharges.
  • Is regularly3 discharged to any depth of discharge.
  • Following first use is subjected to periods longer than 1 month without charge in any 6 month period.
  • Following first use is left in a partial state of discharge for >1 week.

Yuasa VRLA CYCLIC Battery types: NPC, REC, ENL, SLE


  1. Float charge can include intermittent charging patterns, having periods when fully charged batteries stand at open circuit. However, to ensure battery strings are correctly equalised for state of charge and charge acceptance characteristics, continuous float charge conditions should be applied for at least 6 months after commissioning or alterations to battery configuration.
  2. Depth of Discharge (DOD). 100% Discharge in regards to this document should be considered to be end of calculated autonomy period at any given load. A 10% discharge would be a discharge time of 10% of the calculated autonomy at a given load.
  3. ‘Regular’ could be considered as more than twice per month on average.