Inflated / bad batteries can cause a lot of issues the most concerning being a fire and or explosion..
How can you tell if a laptop batter is bad or inflated. You cant always sometimes they even test as good, but subtle things will indicate they maybe inflated and a danger to you and your home.. For example the laptop pictured above is plugged into a known good charger but not charging..
This example of an inflated laptop battery you can clearly see the palm rest of the laptop is budging upward it also made the touch pad very difficult to use as the pressure from the inflated battery is causing it to not seat correctly..
This particular laptop should have a slight curve in this area but not as much as it currently does this is an indication the battery is inflated..