Small Engines (Lawn Mowers, etc.): charging system, john deere lx178, battery down

Question
QUESTION: i have a john deere LX178 riding mower, with a kawasaki FD440 engine.  it doesn't charge.  it drains the battery dead. can you tell me what i need to check and how to test the voltage regulator and whatever else i might need to test. maybe you can give me a step by step on testing with a meter.  thanks

ANSWER: This is not a FD440 manual but the regulator should be very similar is not the exact same.

http://www3.kawpowr.com/enginesecure/ServiceManuals/FC290V.pdf

Do you have a voltmeter?  Can you use the mower if you charge the battery and then start it?

Eric

---------- FOLLOW-UP ----------

QUESTION: i do have a voltmeter.  i can start the mower and drive it.  then after a while it shuts down.  i went an bought a new battery and it cranked. i had like 12.44 volts. when i put the blade on and checked the volts again it started going down to 11 something and more, so i turn off the mower. something is draining the battery down.  this mower was given to me by my father-in-law.  he bought a new battery and put it in wrong.  i forgot what he said happend.  anyway when he had it would run but shut down.  that is because the battery won't stay charged.  so he must have burnt something.  i did check the fuses and they were good.  maybe this might help you solve the problem.  thanks

Answer
I have casued regulators to fail when hooking up the battery backwards.  Does your engine have a 3 pin or 6 pin regulator?  The manual link covers testing the regulator.  Most manufactures only use a couple of regulators so I'd recommend checking the regulator resistance, per the manual, and then measuring the AC output of the alternator and the DC output of the regulator.

A quick and dirty test to see if the battery is being charged is to start the mower, run the engine up to full speed and then check the DC voltage at the battery.  You should have at least 12v DC, minimum, at the battery.

Let me know what you find.

Eric