Most PTO clutches draw around 4 to 6 amps. 50 to 70 watts of power. This is a continuous draw. A starter motor amp draw with no load is around 50 amps and under a load over a 100 amps. Around 1200 watts of power. This is a very short term draw. The battery in a mower is an energy storage tank that is designed for large current draws for a very short period and then be recharged fairly quickly. The charging system on MOST engines is designed to provide enough power to operate the PTO clutch AND replace the relatively small amount of energy the battery used in starting the engine. This takes a few minutes depending on the battery and charging system. If the battery is low on charge and a jump pack is used to start the engine and the PTO engaged the charging system will be putting out its max current for a much longer time like an hour or so trying to power the PTO and put a lot of energy into the discharged battery. Most small engine stators are not designed to do that and they overheat and get fried and sometimes the regulator also. I have seen the AC wires from stators burned off the insulation from this.
