You have an inverter.. Likely an inverter/charger.. The Charger module is either deffective or turned off by you by accident.
I have such a device,, However It is aftermarket,, the original converter is still in place.. Because I like the "Programming" better on the original (Progressive Dynamics 9180 with wizard) I turn off my Inverter's charger module. Most of the time.. (Long story the 9180 is a plug in model,,,sometimes it is not plugged in).
Home is where I park it!