Having backup power in case of outages is critical for many households. The right system can keep vital medical equipment going or prevent food from spoiling. Even folks who enjoy off-grid living need a backup in case larger generators fail. But these systems can be pricey. Luckily, thanks to an early Black Friday sale in conjunction with an exclusive offer code, CNET readers can save big time on one of our favorite whole-home power sources from EcoFlow. Right now at Wellbots you can save more than $1,500 on the EcoFlow…