Small Engines (Lawn Mowers, etc.): scotts, trickle charger, battery cables

Question
Hello Eric. I have a question regarding a scotts lawnmower model# s2348. My question is with the battery and key switch. My friend has the mower and he wants me to look at it. Some times when he cuts grass the blades will just cut off and mower dies. somebody told him it was pto switch. But it wasn't the switch. The battery keeps discharging. Bought a new battery about 2 weeks ago and it worked fine pto and everything, to cut grass.Now it is dead again. Also the key switch won't work. you turn to run and lights come on, but you turn to start it won't work. It almost is like when you turn to start it goes back to run. He has been crossing solenoid to get to crank. Any ideas on what could be causing this problem. I have experience with multimeter and know how to bypass switches. What ever it is it keeps killing battery. Do you think it could be regulator or bad ground somewhere. Or do you think the switch could be causing problem. I have looked on john deere site and there is some kind of sensor it says battery discharge for comments. Also the switch don't work and he crosses solenoid but the battery light stays on all the time. Any help would be helpful. Just that i would ask a expert first. The engine is a kohler cv23s

Answer
First, dis-connect the battery cables and clean both the cable ends and battery terminals with a wirebrush...I have solved a lot of problems doing this.

Charge the battery with a Battery Tender or trickle charger.  Reconnect the battery and check the voltage with the engine off.  Record the reading.  Start the mower and measure the voltage with the engine at full speed.  Record the value.

As for the starting issue, there is most likely a bad safety switch.  On the solenoid, there will be one or two small wires.  If there is only one wire, it should have 12 volts DC on it when the key is in the start position.  Of course make sure the blades are off, the clutch depressed...just as if you were starting the mower.  If there is no voltage then you obviously have a problem.  If you have two wires one is ground and the other is the exicter (12 v DC) when in the start position.

Go to this site to check the switch...you should have one of the switch configurations listed.

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

Although the site is Briggs, the key switches are pretty much all the same, 5 pin or 6 pin.  Remove the switch so you can see the letters, if there are any, on the underside of the switch.  The "S" or pin 4 should send 12 v DC to the solenoid when in the start position.  If there is no voltage on the switch then a safety switch in the circuit is open.

Let me know what the voltage readings are after you charge the battery.

Eric