Lithium batteries require a special charger. The Optimate TM-291 Lithium charger will charge and maintain your lithium battery with 5 amps. This charger can also restore a Lithium battery that has been over discharged, by being left idle for long periods(>year). To reset an EarthX battery that is in the over discharge protection mode, connect alligator clips FIRST, and then plug unit into the wall. You will see the lights go to the save mode. Use with ETX-24C for example.