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Schumacher SE-1555A Failure Codes and Troubleshooting Guide
SE-1555A Failure Codes
FAILURE CODE	DESCRIPTION	CAUSE
F01	The battery voltage is still under 10V (for a 12V battery) or 5V (for a 6V battery) after 2 hours of charging.	Could be caused by trying to charge a 6 volt battery on the 12 volt charger, or the battery could be bad; have it checked or replaced.
F02	The charger cannot desulfate the battery.	The battery could not be desulfated; have it checked or replaced.
F03	The battery was unable to reach the “full charged” voltage.	Could be caused by trying to charge a large battery or bank of batteries on too low of a current setting, or the battery may have a shorted cell. Try again with a higher current setting, or have the battery checked or replaced.
F05	The charger was unable to keep the battery fully charged in maintain mode.	The battery won’t hold a charge. Could be caused by a drain on the battery or the battery could be bad. Make sure there are no loads on the battery. If there are, remove them. If there are none, have the battery checked or replaced.
F06	The charger detected that the battery may be getting too hot (thermal runaway).	The charger automatically shuts the current off if it detects the battery may be getting too hot or the battery may have a shorted cell. Have the battery checked or replaced.
If you get a failure code you have to check the connections and settings and / or replace the battery.
SE-1555A Troubleshooting Guide
PROBLEM	POSSIBLE CAUSE	SOLUTION
Battery clips do not spark when touched together.	The charger is equipped with an auto-start feature. It will not supply current to the battery clips until a battery is properly connected. Meaning, the clips will not spark if touched together.	No problem, this is a normal condition.
The charger is making an audible clicking sound.	Circuit breaker is cycling.	The settings may be wrong. Check the charger settings.
	Battery is defective.	Have the battery checked.
	Shorted battery cables or clips.	Circuit breaker cycles when current draw is too high. Check for shorted cables or clips and replace if necessary.
	Severely discharged battery, but otherwise it is a good battery.	The battery may not want to accept a charge due to a run-down state. Allow charging to continue until battery has a chance to recover sufficiently to take a charge. If more than 20 minutes, stop charging and have the battery checked.
	Reverse connections at battery.	Shut the charger off and correct the lead connections.
Charger makes a loud buzz or hum.	Transformer laminations vibrate (buzz).	No problem, this is a normal condition.
	Shorted Diode Assembly or Output Rectifier Assembly (hum).	Have charger checked by a qualified technician.
CONNECTED (red) LED is not on.	Clips are not making a good connection to the battery.	Check for poor connection to battery and frame. Make sure connection points are clean. Rock clips back and forth for a better connection.
	Connections are reversed.	Unplug the charger and reverse the clips.
	Battery is defective (will not accept a charge).	Have battery checked.
Short or no start cycle when cranking engine.	Drawing more than the Engine Start rate.	Crank time varies with the amount of current drawn. If cranking draws more than the Engine Start rate, crank time may be less than 3 seconds.
	Failure to wait 4 minutes (240 seconds) between cranks.	Wait 4 minutes of rest time before the next crank.
	Clips are not making a good connection.	Check for poor connection at battery and frame.
	AC cord and/or extension cord is loose.	Check power cord and extension cord for loose fitting plug.
	No power at receptacle.	Check for open fuse or circuit breaker supplying AC outlet.
	The charger may be overheated.	The thermal protector may have tripped and needs a little longer to reset. Make sure the charger vents are not blocked. Wait and try again.
	Battery may be severely discharged.	On a severely discharged battery, charge for 10 to 15 minutes in the 55 amp charge rate to help assist in cranking.
Charger will not turn on when properly connected.	AC outlet is dead.	Check for open fuse or circuit breaker supplying AC outlet.
	Poor electrical connection.	Check power cord and extension cord for loose fitting plug.
	Function switch is in the OFF position.	Turn Function switch ON.
The battery is connected and the charger is on, but is not charging.	Clips are not making a good connection.	Check for poor connection at battery and frame. Make sure connecting points are clean. Rock clips back and forth for a better connection.
The measured current is much lower than what was selected.	The charger reached the maximum voltage and is reducing the current.	No problem, this is a normal condition.
Schumacher User Manual Link

When a charging problem arises, make certain that the battery is capable of accepting a normal charge. Double check all connections, AC outlet for a full 120-volts, charger clips for correct polarity and the quality of the connections from the cables to the clips and from the clips to the battery system. The clips must be clean.

When a battery is very cold, partially charged or sulfated, it will not draw the full rated amperes from the charger. It is both dangerous and damaging to a battery to force higher amperage into it than it can effectively use in recharging.