Less battery life after dropping

About 6 months ago, my computer fell from the hook on a door to the ground. Although it was in a case and a backpack, the top left corner of the inner panel separated a little from the outer cover panel and the metal panel that is inside there also got a little warped. Everything has worked fine, but the battery life since then has sucked. Sometimes it seems to charge slower than it should, but mostly there is just less battery life than there used to be. I'm wondering if this is perhaps because the charger is in the same area as where I dropped it, or if the battery is just old, or maybe something else. I don't know what to fix.