Huawei H715BL low battery life?

I have a Huawei H715BL phone (along with my brother) and I really like it. Only thing is, battery runs down pretty quickly. Both of our phones. It's not anything we installed because before we installed anything we realised that it runs down pretty quickly. I want to know how to fix this. Did we both get bad batteries? If not, is there a battery upgrade I can buy or something? Please let me know! Thanks!