OK, now check how much the battery indicator say, when you just get the laptop fully charged, as soon as you unplug it from power. You might find a funny number, such as 10 hours or so. The battery indicator, (in practically all Linux) sort of settles around the mid time area. The top and the bottom levels are not really true. Anyway, how about checking how long one charge would last until the laptop goes off? A few times like that, you’d really know how long the battery life is.