First post, hope this is appropriate for forum: I am wanting to build a friend a cabinet which will house a record player which will go to one speaker. This is going to be in a cabin and I don't want a stereo sound. I want it to sound "old." Anyway he uses a generator for electricity and eventually he is going to be putting batteries up there which the generator will charge. But for my project I was thinking of having 1 or 2 motorcycle batteries or possibly one bigger car battery housed in the cabinet which will run the record player. In addition to running the record player it will need to power the speaker. Lastly, depending on the speaker I get and the record player I may need an amplifier, so all together there could be 3 sources drawing electricity. So my question is, how can I calculate the total draw on the battery and then calculate how long will this play the record player. I assumed I would need a converter that took the 12 volts and converted to 120, but if there is a better answer I am all ears. I am happy to study and do the research, but would appreciate being pointed in the right direction. Thank you.