Let me preface this post by saying that similar to me not being a certified legal expert, I am neither a certified automobile expert. Every car is different. Whether or not an ignition interlock has an effect on your car depends on the car’s condition, among other things.
Caveat aside, for the most part, if you drive your car regularly, you should not have a problem with battery drainage. The only time you may expect your battery to drain is if you don’t use your car for an extended period time. Truth be told, you can drain your battery a lot quicker if you leave your lights on than if you have an ignition interlock.
Be sure to talk with the technician about your car’s battery life to ensure no issues will happen.