The nominal output voltage of the 12V battery pack is 12V, but batteries do not supply as robust an output as wall transformers or vehicle lighter adapters. Therefore a 12V battery pack can be used on the 9V breast pump.
For the 9V Portable Vehicle adapter, the car will output 12 volts (as stated in the car manual) and those 12 volts input into the vehicle adapter which is then converted to output 9 volts into the pump. A 12 V vehicle adapter, like the one your friend gave you, would not be converted and would output 12V into the pump, which is too robust a voltage for the 9V Pump in Style Advanced. We would not recommend using a 12V Vehicle Adapter with your 9V breast pump as it could cause damage.
We hope you find that information helpful. Have a great day!
Date published: 2019-01-24