My IPhone seven battery health draining FAST

So my iPhone seven USED to have a battery health of 83%, not too bad, due it being relatively old. I had dropped it and it had sustained significant cracks, including a complete shattering of the bottom left half of my phone. That was about 6 months ago. The cracks have been getting slightly worse, but not too much worse due to occasional dropping. Here’s the problem. I noticed about a month ago a noticeable difference in battery life. I was worried so I checked the battery health, and it said service. It was on 79% health. I was a tad worried but no to much sweat. I thought I might be natural. But over the last few weeks the health has been plummeting. It is now 70%. Is this anything to do with my cracks? Will fixing the cracks solve my problem? Please help.