Home Green Accessories Guide Why am I getting lesser voltage while using Sears Diehard battery?

Why am I getting lesser voltage while using Sears Diehard battery?

I have an issue with a 03 Wildwood camper. I have a new battery 24m Sears Diehard, connected to a PD4655 converter charger. When connected to shore power everything in the camper runs. No issues at all. When the AC power is gone I get the chirp of the fault and everything goes dark. I tested the charger by using a volt meter on the battery terminals while connected to AC and I am getting a 13.7 volt reading. This is the same reading coming from the posts on the board from converter/ charger. While using the battery I get 12.75 volt at the battery posts and 11.4 volt at board. Even with all the fuses pulled I’m only getting 11.8 volt. Sears tested the battery and told me the battery is fully charged and have no issues. I’m stumped and don’t what direction to move next. Why am I getting lesser voltage while using Sears Diehard battery? Please help. Thanks in advance.