A: Generally, a 12V battery with a voltage lower than 8.5V is damaged and cannot be charged normally. If the battery is damaged or Er4 error is reported, you can select the 12V Supply mode to recover battery charging. Q: Why does battery voltage drop to about 13V after it is charged to above 14V (or when charging stops)? A: The voltage of a fully-charged 12V lead-acid battery is between 12.8V and 13.4V. For effective charging, the battery voltage will reach between 14V and 14.4V during charging time. Therefore, battery voltage will drop to about 12.8V to 13.4V when charging stops (or when charging enters Step 9).
After the battery is fully charged, the charger will resume charging with a small current if the battery voltage is detected to drop to 12.8V. You can also change the resume charging voltage of Lead-acid Battery mode in Step 9 of the Expert Mode . Q: The TB6000Pro Bluetooth cannot be found or connected? A: Check if the Bluetooth icon on the charger screen flashes. If it flashes, turn on Location Services and Bluetooth on your phone (which is necessary for getting the available Bluetooth devices). Then open the app and tap the Bluetooth icon to establish connection. If it remains still, the charger has been connected to another device. 20