# briggs and stratton engine drains battery while running



## sfreda61 (Oct 30, 2012)

"I have a riding mower with a 12.5 hp briggs and stratton engine (model 289707-0154-01). The battery holds a charge but engine the drains the battery when running. I get about 2 time around the yard and the engine sputters and dies. There is barely enough juice to start the mower again. I re-charge the battery and it starts right up. Any idea as what might be causing this? I'm thinking it could be the magneto armature or the alternator or both?


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## Basementgeek (Feb 7, 2005)

Hi and welcome to TSF

Does the mower have a power PTO for the deck? A power PTO will be a switch you turn on/off to engage the blades.

If so, try running the mower for a while with the blades off. Does it restart OK? If so the PTO has short in the wiring.

BG


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## sfreda61 (Oct 30, 2012)

It seems to run just fine until i engage the blades. Then it drains the battery. Perhaps the safety switch for the blades is grounding out. It's an older model MTD, so I don't have a PTO, I engage the blades with a handle. There are several safety switches, seat, must be out of gear & blades must be disengaged before it can be started.


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## Basementgeek (Feb 7, 2005)

Do you have a volt meter that does both DC volts and AC volts? If so measure the voltage of the battery when it is not running, measure with running and again running with the blades. Post those voltages.

Now repeat the voltage test this time using the AC setting with the engine running.
Anything?

BG


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## Danhunt1981 (Aug 13, 2013)

Did this guy figure out this issue? I'm helping my neighbor out with his cub cadet, 22 hp b&s motor and its doing the same thing. 12.4 volts on battery, when running and no pto 14.7 volts, when blades engaged 11.9 volts. Guess I'm looking for a short in the pto switch or wiring? (not a very good electrician...)


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## Basementgeek (Feb 7, 2005)

Hi and welcome to TSF

We never heard back, so we don't know. 


I think the big question for you is, does the mower always start, on its on? own

BG


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## Danhunt1981 (Aug 13, 2013)

Thanks for the reply.
The mower does not start on its own. It will crank but slowly. The service manual says at full charge the battery should read 12.7 volts, but when I read it the other day it read 12.4. My neighbor says its a brand new battery beginning of this season, if I get time tonight I will check and make sure its sized right.


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