Click here for the details, https://earthxbatteries.com/our-batteries/battery-charging. In the event you have to charge the battery, do not use a charger that has a de-sulfate mode;  an automatic de-sulfate mode; or a charger that will pulse above 15 volts!  This will void the warranty and damage the battery. Use an approved “modern” lead-acid battery charger or Lithium battery charger. By “modern” we mean a charger that was built in the last 10 years that automatically turns off when the battery is fully charged (based on volts).  If you are unsure of the charging voltage,  use a voltmeter to check the voltage while charging (do not exceed 14.6V).