2005 Polaris 500. 3000 lb winch. Was working great. All of a sudden if I try to raise or lower the blade, the engine dies. If I hook a battery charger to the winch, it lifts and lowers no problem. In other words, if I idle the atv with the charger hooked to the battery, no problem. If I try to run the winch from the power of the atv, it idles good until I try to use the winch. Battery voltage is 12.5 volts so I think the sealed battery is ok. What could cause this? Engine will die instantly if negative cable is disconnected.