noeifevo 88 2 v 5a lithium battery charger for 77 7 v 21s battery automatic shutoff aluminum case with fan silverDue to some batteries with M25 charging connectors that have integrated charging protocols, our charger cannot support batteries with built in charging protocols. Please confirm with the battery supplier before purchase whether the battery has an integrated charging protocol. For M25 (2+1+5) and M25 (2+4), the standard polarity is 1+ for positive and 2 for negative. If you require a different polarity, please let us know. Contact options: You can