Ok kids classtime

I think one of the issues here is, and I do not mean this offensively, you do not understand how the math behind this works.

Please allow me to help.

Most batteries are termed in volts and amps or amp hours to be specific.

Most devices are in watts of power per hour of use.

Thus if you have a device that draws 50 watts of power and you have a 12 volt battery with 20 AH [amp hours] to see how long it will run "roughly" use this formula.

W=watts

E=volts

I=amps

W/E=I

So in our example

50/12=4.1666 amp use per hour so a battery with 20 AH will run the device for about 4 hours give or take.

This is a simplified view as you have to take into consideration the battery type amd amount of discharge it can handle per cycle.

Hope this helps...and I hope I didnt miss anything, not much coffee yet