[tzsuzuki]

I purchased a 2015 xc300e racing this past June. The battery that came in it failed in 6 weeks. The dealer gave me a new one, thought nothing more about it. A month ago that battery seemed to get weak, wasn't spinning starter. I was using a battery tender on it to keep it up even though I ride it at least once a week.
I bought a Lithuim ion battery this time around, partly for the weight savings. This morning it wouldn't spin the starter. I kicked it took many kicks to get it started which I thought odd, it was cold though.
I rode about ten miles returned to the truck for a break. When I went to start it it wouldn't. This time the lights didn't work or the horn. No spark either.
When I got home I put the old lead acid battery in, lights and horn work, kicked it over started. I measured the voltage when running 14 volts.
Do I have some underlying problem causing this?
Why wouldn't the bike start with a dead battery? I remember reading that once a lithium battery is discharged to a certain point it has some protection built in that prevents further discharge and damage.
Any thoughts?