Optimate III Deep Discharge Howto


Optimate III when connected to the battery, lit only the power LED, none of the four status lights.


Optimate III won’t even try charging a battery if the voltage left is < 2V (what’s called a deep discharge).


  • Disconnect the battery from the bike (to prevent damage to the electronics)
  • Hook the charger up to a working battery
  • Quickly move the cables from the fresh battery to the “dead” one. If the charging light goes out before the charger gets reconnected, you’re too slow.
  • Wait patiently

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