There is no instruction manual or similar. There are no detailed explanations of the operation of the Power Supply and voltage adjustment. Using a 12V, 7Ah lead battery it is mandatory to adjust the output voltage of the switching power supply to 13.8V. Otherwise the battery not reaches fully charge. Is sold as a 12V supply, but cannot be used with a 12V output. The battery was discharged until the protection at low voltage turned off the output, when the voltage dropped to 11V (Not 10V as described in the advertisement). This means that I have a very narrow operating range: on the one hand, the battery does not reach a full charge and on the other hand, the low voltage protection shuts off the output early. The time of the power supply running after the power failure is very short! The CHUX Official Store does not answer any post about this since Dec/03. (18 days ago.)