Add to Cart OutBack Power Systems OutBack Power FM80-150VDC FLEXMax 80 Charge Controller $399.98 OutBack Power FM80-150VDC FLEXMax 80 Charge Controller 80A. The FLEXmax family of charge controllers is the latest innovation in Maximum Power Point Tracking (MPPT) charge controllers from OutBack Power. The innovative FLEXmax MPPT software algorithm... Compare Add to Cart Add to Wishlist