Outdoor Power Equipment and Small Engines - John Deere Ztrak 727 won't hold charge

Tried to start this morning, nothing at all happened. Attached battery boost, started and held for about 5 minutes then cut off.
With boost continuously in on position, everything worked fine until boost ran down.
Turning on PTO led to quicker battery drain as expected.
Parking break switch is acting up but not sure if this is a separate issue.
I think it is more than just the battery, something is causing a drain down, Any help appreciated.

I really don't understand,,(Attached battery boost, started and held for about 5 minutes then cut off.) Did you crank it for 5 mins, than it wouldn't crank?? (With boost continuously in on position, everything worked fine until boost ran down.
Turning on PTO led to quicker battery drain as expected.) Is this a booster pack you're using?? Have you actually tested the battery with a load tester, (not just check the voltage on it)?? Clear up some things & we'll get to the bottom of it... Roger

Roger, have not load tested the battery. The mower would not
start. I could hear the starter when the key turned, but no other sound was present.
I then attached a charge booster. The mower started right up.
I immediately removed the charger. I was able to ride around for a few minutes without engaging the PTO. As soon as I turned on the PTO, the mover cut out.
I tried again, this time leaving the charge booster attached. Again the mover started right up and even allowed me to engage the PTO normally. I then shut off the PTO, took off the charger/ booster and waited. THe engine continued to run for about 3 more minutes, then died.
I don't think this is simply a dead battery. Something caused it to drain down in the first place since I last used it 1 week ago.
David

How old is the battery. Have you checked to see if the engine is charging the battery while it is running?

Had a simular instance on my personal unit where I found the cable to the battery had a bad connection of the connector on the cable. Ended up replacing the cable end and everything worked good. It also sounds as if your engine is not putting out a charge. With a good charged battery, you can troubleshot your units electrocal system, even if you have a good jumper set up to a good battery and your battery still in the unit. A good volt meter should show between 13 and 14.4 volts with the engine running at the battery. The center post on the voltage regulator on the engine and ground should have 12 volts with the engine off and the ignition switch on, if not look at a bad connection on the switch or a bad switch. If that is okay then with the engine running, you should show about 14.4 volts between the center lug on the regulator and ground. If not then the regular is a problem. Good Luck