Over the past month, the only way I have been able to start the lawn tractor has been by jumping it. I had a portable booster, but it died.

I suspect a bad battery, but it's about a year old (not talking about the booster).

The voltage on the battery reads 10V. When I do start the engine by jumping it, the voltage goes up to 14.5V, which I believe means that all charging systems are working fine (coil and cables). The voltage reads the same from the battery to the starter (10V).

However today, something happened that might narrow down the problem (before I change the battery). When I jumped the battery with my car (which I turned off), the tractor started fine. However, as soon as I removed the jumper cable, the tractor started to choke, with exhaust fumes spitting out, and eventually stalled. I'm assuming that it flooded because I have not been able to start it back right away (even when jumped). It will turn, but soon after will stop. It will turn again when I turn the key, but will again stop soon after. There are some fast clicking sounds in the mix as well and the starter doesn't rise to the fly wheel (although it does turn).

I hope that I'm making sense. One thing that confuses me is why would it start to choke up after removing the jumper cable. Is the battery still performing some function to the engine running? I have no head lights or auxiliary systems.

The one thing that I wasn't able to do is voltage drops, as that needs 2 people.

I'm open to do any tests. All feedback will be appreciated.