Troubleshooting

The information on this page is meant to address common troubleshooting issues, and as a result, is not comprehensive of every occurrence you may experience with your Schumacher product. It’s always best to refer to your product’s specifications and features to ensure you’re using the correct voltage/amperage at any given time. If you’re still having issues with your Schumacher product, please contact customer service either online or via phone.

What does this error code mean?

While not comprehensive, here is a list of digital battery charger error codes that are commonly seen along with a troubleshooting tactic to fix it

Error Code	Description	Reason/ Solution
F01	The battery voltage is still under 10 volts (for a 12-volt battery) or 5 volts (for a 6-volt battery) after two hours of charging.	The battery could be bad. Have it checked or replaced.
SUL	The charger has detected a sulfated battery.	The charger will go into desulfation mode. If the desulfation is not successful after 10 hours, the charger will go into abort mode.
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	This may be caused by trying to charge a large battery or bank of batteries on too low of a current setting. Try again with a higher current setting or have the battery checked or replaced
F04	The connections to the battery are reversed.	The battery is connected backwards. Unplug the charger and reverse the connections to the battery.
F05	The charger was unable to keep the battery fully charged in maintain mode.	The battery won’t hold a charge. This may 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 deteced 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. Have the battery checked or replaced.
F07	The charge shut off because its internal temperature exceeds limit.	Make sure the charger does not have the side ventilation holes blocked. Move the charger out of the sun and into the shade.
F08	The battery voltage dropped too low during the maintain mode.	This may 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

Why am I getting a low or no output voltage reading from my inverter?

Either you have poor connection at the terminals, or you are using an incorrect type of voltmeter to test the output voltage. Check and clean the 12-volt connections to see if that improves connection at the terminals. To ensure you’re getting the proper output voltage reading, make sure you’re using a true RMS reading meter.

Why is the red LED on my inverter on?

There are several reasons the red LED on your inverter is on. Here are just a few reasons along with troubleshooting tactics you can use to address the issue:

When the power input from the vehicle’s battery drops below 11 volts, low battery shutdown occurs, and the inverter shuts off; try recharging or replacing the battery.
When the power input from the vehicle’s battery exceeds 15-volts, high voltage overload protection occurs; try reducing the voltage range so that it’s between 12-volts and 14-volts.
Install a new fuse that is the exact same type and rating. The continuous load demand from the equipment or device being operated exceeds the continuous load rating of the inverter being used; try using a higher capacity inverter or lower rated device.
If the case temperature becomes hot (exceeds 145°F), allow the inverter to cool. Do not block the cooling slots or air flow over and through the inverter. Reduce the load on the inverter to the continuous rated output.

Why is the low battery alarm always on?

There can be several reasons why the low battery alarm is on. Here are a few reasons and troubleshooting tactics you can use to address this issue:

The power input from the vehicle’s battery is below 11 volts; try recharging or replacing the battery.
The battery is in poor or weak condition; try recharging or replacing the battery.
Inadequate power is being delivered to the inverter or there is an excessive voltage drop; try checking the condition of your cigarette lighter socket. Clean or replace if necessary.

I am trying to operate a TV with my inverter, but the TV doesn’t work. What can I do?

Try turning the inverter on, then off, then on again. Contact the TV manufacturer for startup surge rating and/or if the TV is compatible with a modified sine wave. An inverter producing a larger power output may be required.

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