09-12-2019, 08:23 PM

I'm new to all this so have mercy please. I need to power my laptop for 15 hours max between charges. My laptop uses about 20 watts. Is my math correct? 15x20=300 watt hrs/12 volts=25 amp hrs x 2 (max 50% drain) = 50 amp hr + (how much for inverter draw?) = X amp hr battery needed. Thanks.