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error Schumacher
Error Code SUL
The charger has detected a sulfated battery and is going into desulfation mode. If unsuccessful, it will move to abort mode.
? What Causes This
Battery may have been left unattended for an extended period leading to sulfate build-up on the plates.
✓ How to Fix It
Unplug charger, check battery condition. Replace if necessary after checking voltage with a multimeter and measuring specific gravity of electrolyte.
Source: page 10 of the official manual
From the manual
This error code appears in:
Schumacher Sc1308