Before you replace your battery, let alone install an auxiliary battery, it's important to make sure that there isn't a parasitic drain in the system.
Tupu ị dochie batrị gị, ka ọ bụrụ na ị wụnye batrị inyeaka, ọ dị mkpa iji jide n'aka na ọ dịghị ihe nchịkọta parasitic na usoro ahụ.