Why does my chevy tahoe have no power at all?

If Your Chevy Tahoe has no power at all make sure the in-line fuse holder is tight. Also check the ground from the battery to the frame. I've replaced 3-4 of those wires because the crimped end came loose from the wire. If that's not Your problem then it could be the new battery. Your car battery provides the zap of electricity needed to put electrical components to work. It also converts chemical energy into the electrical energy that powers Your car and delivers voltage to its starter. And it stabilizes the voltage (a.k.a. Energy supply) that keeps Your engine running. Important, indeed. Depending on power, size, and quality, prices for a replacement car battery range from about $40 to $250.