If you buy new batteries make sure they have the same balance tap since your E-flight charger uses it to charge your batteries. E-flight uses what is ofter called an Align balance tap. If you get a new charger you will most likely have to buy a separate balancer and other hardware. It can be a very deep rabbit hole to climb out of. You may want to check in the battery forums and do some reading there. Lots of info, just takes some time to read and make sence of it all. Best of luck