Jackery 240 vs Goal Zero 200X Staying Warm Winter Tent Camping

I tested out ways to stay warm when winter roof top tent camping. I used a 12V heated blanket that's about the size of a throw blanket and made for cars with a 12V car plug. The Jackery Lasted 13 hours and the Goal Zero lasted about 6 hours. I have no idea why Jackery did so much better.