Due 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 purchasing 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:You can reach us online or send an email to sale@noeifevo.de.