During normal engine operation it learns and adapts to driving style, engine component performance, does mild "tweaks" here and there. The learning process is running all the time during operation. One of components is the throttle plate position. When you disconnect the battery, all that information is lost, but when you sit back behind the wheel, the learning continues same as before the battery disconnection. It takes few hundred miles for the engine ECU to relearn - get to the point of learning where it was.

Think of shoes, that were old and comfy and you've got new ones - you'll need to adapt. This is same if you fit a new engine component, ECU need to learn it.
However, if you forgot how your shoes were, and need some time to get used to them again - this is battery disconnection.

If you need to disconnect the battery, feel free to do so. You may feel the car responds a bit different later, but it will become same after few hundred miles.

 

Thank you.

 

If you have a radio that requires a code, you will need to re-enter that code, so make sure you have that handy.