noeifevo 29 2v 2a 3a 4a 5a lifepo4 battery charger for 8s 24v 25 6v lifepo4 battery cool fan automatic shutoff greenDue 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 need a different polarity, please let us know. Contact options: You can reach