As long as the DC output voltage of the generator is equal to the voltage at the battery terminals. The generator has high power and the battery power is low, so there will be no impact. It has nothing to do with the power of the generator and can be used with confidence.
Give an example. The voltage of the mobile phone is 4.3 V. If the 4.3 V charger is plugged into the 220 V electricity network, it does not take into account the power of the electricity network (tens of thousands of kilowatts) and it can be used normally.
The generator is equivalent to the power grid, the DC output voltage of the generator is equivalent to the output voltage of the charger, and the battery is equivalent to the cell phone battery.