My Kohler Command 25 hp now runs WOT on its own

[Bleach]

I hope it didn't fry my ignition coils. I replaced them last winter. I've lately gotten tired of throwing money at this thing although it hasn't been much over a $100 yet. It's still less than a new mower.

 

[cpurvis]

I doubt that it did...otherwise, it wouldn't have been running for you to shut off.

More likely something in the charging circuit.

Who knows? Maybe your diagnosis of the 9 year old battery giving out is correct.

 

[Bleach]

I'm hoping that it's just the battery. It's just odd to see a battery seemingly boil like it did. I wasn't paying attention to the gauge before this happened. It was cranking perfectly until about half an hour before this. I had shut down the mower and then when I wanted to start again, the battery seemed like it was low on charge. I hooked up a charger and after a short charge was able to restart easily. It ran ok for a while and then it happened.