There was a time when it was a simple old one out, new one in task. But replacing the battery on a modern vehicle is now much more involved. It is absolutely essential the battery on newer vehicles is replaced with one of the correct specification. If a vehicle is fitted with an AGM Start-Stop battery then the replacement must also be AGM Start-Stop. The same applies to EFB specification products. The fitter also needs to tell the vehicle what has been done.