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PK., Small Engine Technician
Category: Small Engine
Satisfied Customers: 1052
Experience:  Retired Owner of a full service shop and national parts sales website.
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My JD 120L riding mower drains my battery during every use

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My JD 120L riding mower drains my battery during every use to the point that I cannot start the mower without a jump from my car battery. Any ideas?
Hi, does the engine die while you are using it or does it not want to start after using it?

How old is the battery?

Thanks, PK.
Customer: replied 3 years ago.

It does not want to start after using it. I bought a new battery. I still needed to jump start the mower with my car battery.

Does it start just fine every once in awhile but most of the time the engine just won't turn over and the starter makes a humming sound or sounds like it's struggling?

If you have a voltmeter, can you check the battery voltage?
Customer: replied 3 years ago.

The engine does not turn over at all. Nothing happens when I turn on the key. It struggles to start when I jump start it. I do not have a volt meter.

You'll really need a voltmeter to track this down. A decent one can be had for around $20 at any auto parts store.

It could be a bad battery cable connection, a bad ground between the engine and frame, a bad battery cable, a bad starter, a battery that's failing, a key switch issue, an alternator problem or that the valves need to be adjusted.

What we would do first is establish the battery has a little over 12 volts. Then we'd establish the ground between the starter housing and the negative post on the battery is good. Then that the starter is receiving 12 or so volts when the key is switched to Start. If all that checks out, then it may be that you have a compression release that's not functioning and that requires adjusting the valves.

I can walk you through all of this and we should be able to find the problem, but a voltmeter would be required.

Thanks, PK.
PK. and 2 other Small Engine Specialists are ready to help you
Customer: replied 3 years ago.

I'll purchase a voltmeter and then respond to you when I am ready to troubleshoot. Thanks for the guidance so far...I'll be in touch.

Thanks! I'm usually on here off and on Saturday and Sunday and most weeknights. Just reply back with what you find and I'll reply when I log in.
Customer: replied 3 years ago.



Thank you for the follow up. I have been out of town on business all week. I plan to have a voltmeter by next Saturday. I'll contact you then. Thank you and take care!

Just let me know when you get a chance to check it out.
Customer: replied 3 years ago.
Will do. I appreciate it.
Customer: replied 3 years ago.
PK - "on the road again". I hope to be able to follow up with you this weekend (8/24-25). Thanks for standing by. Have a good week!
Thanks for letting me know!