There is absolutely no way these clamps could be used at 800A. Or even 400. 1. The cable clamps are too small to accommodate over 1-0 cable. And that would be too big to crimp. Solder, only if very proficient. 2. Copper strap connecting cable to jaw way too thin. 3. Only jaw on one side is electrically functional 4. Surface contact area of jaw too small.