Small Engines (Lawn Mowers, etc.): Battery issue?, briggs stratton, key switches

Question
I have a Yardman 15.5HP OHV riding mower.  Engine info: Model: 28N777, Type: 0642-A1, Code: 970123ZD. The engine is made by Briggs & Stratton. I changed the battery & used it 1 time. Next time battery was dead. I charged the battery & had it tested & was told it's ok. I put it back on the mower and the next day it was dead again.  Any suggestions?  Also do you know where I can get a manual for this engine?

Answer
The link below provides a great description of your mower's electrical system.

http://www4.briggsandstratton.com/miscpdfs/RNT/alternator_replacement.pdf

I have found bad key switches drain batteries as well as a diode (once) that drained the battery.

If you have a voltmeter, I would measure the battery voltage draw with the mower shut-off to determine if the there is any voltage being drawn.

Let me know if the link helps.

Eric