Grasshopper 932 Stalls Unexpectedly

My Grasshopper 932 stalls unexpectedly while mowing. It doesn't cough or sputter, it just dies. After restarting, I can mow for a few minutes before it dies again. The first time it did this, it started right up the next day without battery charging. The second time, I had to jump it with my pickup truck. The 3rd time, I tried jumping it with my pickup truck but it just clicks when I engage the key. I assume this is a alternator or starter issue but I would like someone else's opinion before buying new parts.