Having problems with my lawn mower, need some help

A

Andrew Holley

Well-known member
I have a older Simplicity front deck mower, out mowing lawn tonight and the mower deck stopped spinning, thought I busted a the belt but no. Looked underneath and I saw the negative battery cable dragging, had melted the terminal off the battery (motor still running). Drove it into the garage, with the motor running, put the meter probes on what was left of the negative battery terminal and the negative cable and got 12.83 volts??? With the motor off, I get nothing.
Thinking the start is shot, leaking voltage thur it's housing to the frame, terminal was the weakest link and melted off from the heat of the resistance.
Holding the ignition key to start, and tapping the negative cable to the battery, I can start the motor, but large sparks/flash and doesn't stay running.
Any good free advice out there? Not really wanting to take it somewhere, too cheap.
Thanks in advance.
 
Andrew, I don't have a really clear picture of what you are finding but if you can jump to the starter and it starts it seems to me the starter is OK. The 12.83 you are reading when it is running is output from the charging system. I doubt the terminal melted off from being the weakest link, more likely it came loose and then the high resistance melted the terminal/ cable end. The part about it not staying running is a puzzle yet but I would fix the cable end first and then check battery voltage neg to neg and pos to pos with your meter. When you hooked your meter up between the battery and cable were you checking volts? Also if your battery is shot just go get a new one and then proceed with caution. Remember free advice is usually worth what you pay for it.
 
Tom, I would usually agree with you about free advice, but I am ever amazed with the knowledge you can get off this board.
Here is what I have been playing with:
With the igniation key on, from the negative battery cable to what's left of the negative battery terminal, I get 12 volts. To me, that means the frame is now positive instead of negative, correct? So somewhere I have a short.
Now here is what I didn't notice the first time, there is a mesh grill on the side that made contact with the line (battery) side of the solenoid, got burns/melted metal.
I have disconnected every module/solenoid/sensor I can find and still have voltage from the frame/ground cable to the negative battery terminal.
SO, did the contact between the mesh grill to the solenoid cause the terminal to melt and my voltage test is nothing? Or do I have I have a problem in the wiring harness, that something melted together??
Thinking about buying a new battery, hooking it up and seeing what happens, but I remember a car battery exploding in high school shop class, and that scares me.
 
Working backwards, batteries can and do explode. I blew a couple of big ones up in the navy that was epic, my dad almost sprayed his face with acid by blowing up a tractor battery. But I digress. Right now I suspect the solenoid is shorted to the frame (ground). I find people use he term "short" fairly loosely to describe any electrical problem but it does sound like you do have a short and more specifically a short to ground or "dead short". I used to teach that there are only three kinds of electrical problems. 1. Open- an example would be a broken wire. 2. Short- an example would be wires in a wound coil that have bad insulation creating a shortcut for the current. That would show up as a lower resistance than spec. And actually that is fairly rare. 3. And then the granddaddy of them all the dead short, that is when the battery is connected somehow + to - direct = big sparks, heat and possibly BOOM. Back to my best guess, the positive side of the solenoid shorted to ground and burned off the ground cable. When you hook up the new battery just make sure that the area is ventilated well and if it sparks disconnect it. Another safety tip is to make the final connection away from the battery if you can. What explodes is the hydrogen gas produced by a charging battery so if it is just out of the box it should be OK. You could just fix the ground cable and then use a jumper to the starter to see if it is good. Good luck and let me know.
 
Put in the new battery, replaced a couple of wires in the harness, that I believe were causing the short and she started right and finished mowing lawn.
Thank for the help Tom, hope to see you in Lacrosse in October, I owe you a beer.
 
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