z10 automatically turns off when battery level is below 10%.

When I was surfing internet this morning, z10 alerted me about battery level below 10%. I didn't turn it off because I was on my way to home. I thought z10 (st100-1)) should hold up and I'd charge it when I was home. I put z10 in my pocket and walked to my car. When I got in my car, z10 was off .

After I charged my phone at home, everything is normal.

I'm using OS 10.1.0.4543 .