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Riding Mower Battery Won't Hold a Charge

Category Lawn Mowers
How can you get the lawn mowed when the battery won't hold a charge? Perhaps a bit of troubleshooting will help you discover the cause and make repairs. This is a guide about riding mower battery won't hold a charge.
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Ask a QuestionHere are the questions asked by community members. Read on to see the answers provided by the ThriftyFun community or ask a new question.

May 7, 20121 found this helpful

I have a Craftsman riding mower. Every time I use it after about 15 minutes of cutting, it cuts off. It drains the battery which I then have to recharge. I have replaced the battery, ignition switch, had the starter rebuilt, solenoid switch replaced, and seat wiring. Any suggestions?

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By NS

Answers

June 7, 20151 found this helpful

Check the part called "Protection Wire Loop". This nothing more than a diode that allows the stator (from your starter unless your model has a full blown alternator) to send one half of the a/c electrical signal (IE: just the positive part of the the alternating current (a/c) sign-wave) back to the battery to charge it. It's a simple way for getting "dc" voltage from an ac source and therefore recharging the battery. IF the diode is bad the battery can't be recharged.

Look at a wiring diagram for your mower and it will probably be labeled something like "Charging System Output." It may even state the rating - IE: 3 Amp @ 3600 RPM.

It's a cheap (maybe as little as 10 cents) part at Radio Shack or order one online for a few bucks. It's an easy cheap thing to check for a fix. My diode had a part number of 1N5404. Hope that helps. Good luck.

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June 10, 20150 found this helpful

In my previous answer I thought they were using the stator from the starter. This is incorrect. The stator is part of the overhead flywheel assy. However, the diode issue is still likely the problem. The diode on my mower was located in the wire harness on the right side at the back of the engine. Trace the wire coming from under the left side of the flywheel around the back of the engine. Begin to open the wire harness just before it joins into the main harness. You will find the diode spliced into a wire. The diode starts the split so that one wire (the continuous one) runs the lights and the diode goes to recharging the battery. The diode will likely be broken and literally fall apart.

I apologize for the misinformation. I'm surprised ThriftyFun does not allow for editing ones own post. Hope that corrected information helps someone.

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September 12, 20160 found this helpful

Would a bad diode also explain the stalling?

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November 14, 20160 found this helpful

I believe I have a ranchero by MTD, it won't hold a charge on the battery while it's running.

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July 19, 20171 found this helpful

Hi NS, I believe you will find that your alternator is not keeping the battery charged as it discharges. For example, the electro-mechanical clutch used to engage the mowing blades consumes roughly 3 to 5 amps when engaged. As the battery voltage drops, there isn't enough electrical power to hold the electronic fuel shutoff solenoid. The solenoid will then close and block fuel from entering the engine. If you have headlights running with 1156 bulbs, which draw 28 watts x 2. To round it off, lets call it 60 watts. 60 divided buy 12 (volts) is roughly a 5 amp draw. A fully charged battery has the capacity of 12.67 (2.12 amps per cell) generally have a 25 amp hour rating. If the amperage draw causes the battery to under 10 volts, the fuel solenoid no longer has enough volts to keep it open after roughly 30 minutes or less when you factor in a 75 amp draw to start the engine. So, to verify, using a voltmeter, start the engine and run it about half throttle or more and take the voltage reading at the battery terminals. If charging properly the voltage should 13.6-14.2 volts. if it is staying at 12 volts, the most likely reason is a defective voltage regulator or a bad connection in the red wire exiting the voltage regulator. Unplug all connectors of that red wire and clean them and if the unit is still not charging, replace the regulator. Hope this helps!

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Kevin,
Kevins Small Engine 03908

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By 0 found this helpful
June 27, 2010

I have a MTD Pro 15.5 hp riding lawnmower that will not stay charged. The battery is new and once charged the mower will run until shut off and will then need to be re-charged. Any suggestions/comments?

By sdokis from Ontario

Answers

June 28, 20102 found this helpful

My John Deere does the same thing. So I bought a charger for 50 bucks at a auto supply store. Now a couple of hours before I mow the grass I hook up the charger. If it is still sluggish I put the charger on boost and have my lady disconnect the charger after the mower starts. Crappy but it works for me.

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April 29, 20111 found this helpful

Our John Deere mower does the same thing!

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June 10, 20151 found this helpful

Check the part called "Protection Wire Loop". This nothing more than a diode (P/N 1N5404) that allows the stator (unless your model has a full blown alternator) to send one half of the a/c electrical signal (IE: just the positive part of the the alternating current (a/c) sign-wave) back to the battery to charge it. It's a simple way for getting "dc" voltage from an ac source and therefore recharging the battery. IF the diode is bad the battery can't be recharged.

Look at a wiring diagram for your mower and it will probably be labeled something like "Charging System Output." It may even state the rating - IE: 3 Amp @ 3600 RPM.

The diode on my mower (Craftsman 16HP LT-1000) was located in the wire harness on the right side at the back of the engine. Trace the wire coming from under the left side of the flywheel around the back of the engine. Begin to open the wire harness just before it joins into the main harness. You will find the diode spliced into a wire. The diode starts the split so that one wire (the continuous one) runs the lights and the diode goes to recharging the battery. The diode will likely be broken and literally fall apart.

It's a cheap (maybe as little as 10 cents) if you can find someplace that has them. Or I ordered one online for a few bucks. It's an easy cheap thing to check for a fix. The diode used had a part number of 1N5404. Hope that helps someone. Good luck.

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September 20, 20150 found this helpful

After you're done using your mower turn it off and raise the seat up and leave it up. Pop had the same problem until he tried that and it works.

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July 30, 20110 found this helpful

I have a 16.5hp MTD riding mower and the battery keeps being drained. We purchased a new battery. As soon as we put it in we had to jump it off. Now it won't even jump off. This is only the second time we have tried to use it since the new battery was installed, 2 weeks ago!

By Michelle

Answers

July 31, 20110 found this helpful

1. I would have the battery checked to see if it indeed drained.
2. What kind of engine do you have.
Reason I ask is I have a John Deere L120 with a Briggs and Stratton engine and it would not start. I though it was the battery. I had it checked at a battery store and they told me it had a full charge. They told me there may be an open ground on the mower. I bought a new battery with more cranking power. I installed the new battery and not even a burp from the engine. I asked a JD dealer what could be the problem. He said the valves were out of adjustment. ( Two dealers have told me the same thing.) He explained I had a Briggs and Stratton engine and they have made junk engines for the past 10 years. He gave this bit of information for me to try. On the top of the engine is the air intake screen. With your hands move the screen in reverse or counter clockwise until you have resistance to the turning. Stop and try starting the mower. It worked for me. So every time I want to start the machine I have to counter turn the air screen untill I feel the resistance. Then it starts. As for the open ground,I checked all the connections as well as the safety connections and found nothing. Maybe this will be of some help for you.

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October 9, 20161 found this helpful

You saved me! Thank you!

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February 19, 20171 found this helpful

I have the same similar issue, but when I place the battery charger on in the start option and wait 10 seconds the motor will turn, but not start

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September 7, 20130 found this helpful

Last year it was working perfectly. After the first lawn cut I turned the tractor off. On the next use it was dead. I noticed the black negative battery cable was all messed up and melted. I bought a new cable and battery and it fired right up, but after each use the battery is dead and needs charge. Any suggestions? I have no way to take it to a shop nor do I have the money. I am living on SSD. It's not the battery. Help! It is an old, but in good shape, Poulan Hyrodrive.

By Roger B

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June 13, 20130 found this helpful

My John Deere Sabre riding lawn mower battery keeps dying? I have changed the starter and the solenoid, but the battery keeps dying between uses. How can I find out if there is some short or if there is a constant drain on the battery?

By David

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April 15, 20130 found this helpful

I have a Poulan pro rider. Something is draining the battery. I replaced it twice and I still have to charge every time we mow.

By Julie from MO

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By 0 found this helpful
September 16, 2010

I have a Murray riding mower. It has a brand new battery and solenoid, but I have to jump it off because the battery won't stay charged while running. How can I fix it?

By Stephen from Memphis, TN

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