Warning: To use this adapter properly, we recommend using a fuse thats rated about 30% higher than the max current you expect to draw. We also recommend adding a low voltage disconnect circuit or a timer to prevent the battery from dropping past low voltage threshold (which will damage the battery or shorten its life span); (Max battery voltage/4.2)*3.3 = typical low voltage threshold. To protect your device you should convert your voltage using a DCDC converter to match your device's acceptable voltage range. We do not recommend buying this item without fully understanding how to use it properly, protect the battery, and the device you intend to power.