Due to some batteries with M25 charging connectors that have built-in charging protocols, our charger cannot support batteries with integrated 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 reach us online or send an email to sale@noeifevo.de.