# Craftsman Riding Lawn Mower - Model No. 917.275670



## FlemingtonNJ (Oct 9, 2010)

My Craftsman riding mower wont start. I have to jump start the mower every time. I charged the battery (it is a one year old battery) and the mower started up. Mowed half the lawn, turned the mower off; the mower started back up without being jumped. Mowed more lawn, turned the mower off, then the battery was dead. Jump started the mower (again). Checked the battery charge and it was dead, so the battery is not charging while the mower is running. So far, I have done the following:

1. Cleaned the battery terminal connectors and the terminal posts.
2. Tested the solenoid. It is good.
3. The ignition works, so no need to check it.
4. Checked the starter using a test light on the grounding plate, the test light lit up, so I am assuming the starter is good as well.

Any ideas what the issue might be?

Cordially,

FlemingtonNJ


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## Bill Kapaun (May 8, 2007)

That engine has a 15 Amp charging system, so it "should" be capable of charging the battery without strain.

Measure the battery voltage OFF and then with the engine running at high speed.
The voltage should increase from about 12.6V up to 14ish.

The alternator can be checked by unplugging it and measuring the AC voltage between the 2 stator leads. It should be 28 VAC MINIMUM at high engine speed.
Between the 2, you should be able to tell if the Voltage regulator is the problem. (make sure VR is grounded well via the mounting screws)

L&G batteries are always suspect, no matter the age.
Most auto parts stores will load test them for free, in hopes of selling a new one.
I suggest you do that to avoid 'chasing your tail".

Briggs OHV engines also need the valve lash correctly adjusted for the compression release to function. It's one of those maintenance items that's usually overlooked.
There IS a "correct" procedure- Piston 1/4" past TDC.


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## FlemingtonNJ (Oct 9, 2010)

Mr. Kapaun;

Apologies for tardy reply. Thank you for the information. Started reading your reply this past Monday; took me some time to read-up on my engine and mower and learn what a Regulator/rectifier is; what an alternator versus stator is, and of course where the heck this stuff is located. Then, I had to learn how to measure DCV and VAC (I initially thought VAC was short for vacuum.....yea I was less than brilliant on that one!). Had to purchase a digital meter since my eyesight could not read my very old analog meter any longer. Then, add in the 50+ you tube videos I had to watch....you can imagine took some time. Now, you have to also add in the time my wife is huranging me for wasting so much time on this 'project' and advising me to take it to the lawn mower shop to have it fixed.....ahh the life of a DIY guy. So far, I have:

1) Checked battery with engine off and it reads 12.75 DC.

2) Checked battery with the engine running at max RPM and it read max 12.65 VDC 

3) Checked VAC output from the Alternator/Stator and it reads 30.5 to 32.1 VAC.

4) Checked DC output from the regulator to the battery at full RPM, it reads 10.5 VDC max.

I will purchase a new regulator and hopefully this solves my problem of a dead battery.

I have not done any reading / you tube on checking correct valve lash / compression release. That will be next.

Thank you for assistance.


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## Bill Kapaun (May 8, 2007)

Sounds like the Voltage Regulator is bad.
HOWEVER- I see a Red Flag....

With the engine running, Voltage at the battery should be the SAME as that of the VR output since they are connected through the key switch. (how else would the battery charge?)

I'd check the connections at the key switch.

There should be an electrical schematic in the Owners Manual.
If you don't have an OM, you can download one at-
searspartsdirect.com


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## FlemingtonNJ (Oct 9, 2010)

*Bad Voltage Regulator but possible Red Flag*

Hi Mr. Kapaun, 

One of the first things I did (before posting on tractorforum.com) was check continuity on the key switch. At the time, it was ok, though I failed to mention this in my first post.

Question: If the VDC is 10.5 from the regulator to the battery, doesn't this mean the regulator is bad / going bad? If the VDC is 12.75 or higher, that would mean the regulator is good? Yes? No? From your first post, I am assuming since the regulator did not go above 12.75 V's, this means it is not charging the battery, and this is the reason I keep getting a dead batter.

Sincerely,


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## Bill Kapaun (May 8, 2007)

FIRST-
I don't know what meter you have, but do this simple test--
Measure a 1.5V penlight/flashlight battery and see how close you are to 1.50V.
I've got one of those "free" Harbor freight meters. It reads 1.62V or 8% high.
Just saying....

I believe when you measured the 12.7 you had the key OFF. That would disconnect the battery from anything else at the key switch.

The RED FLAG is-
When running, the battery IS connected to the VR through the key switch. ERGO, the Voltages SHOULD be the same.

The key switch may test good, but the connector may be "cruddy".
I assume you noticed the "truth table" at the lower left of the schematic depicting the different switch positions.

I just go by Bill. Mr. just makes me feel old.


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## FlemingtonNJ (Oct 9, 2010)

*Bad Voltage Regulator but possible Red Flag*

Finally found some time today to re-attack my riding mower electrical issue.
I did the battery test you suggested with my Craftsman voltmeter. Got 1.62 volts as you said I should.

Also did the following:

1) Battery Test: Turned on mower. Checked voltage for drop. Battery was not charged. Dropped to under 11 volts while mower was at full RPM; I turned off the mower at that point.

2) Checked VAC output from the Alternator/Stator and it reads 30.5 to 32.1 VAC.

3) Checked DC output from the regulator to the battery at full RPM, it reads 10.5 VDC max.

4) Took battery to local shop and had it load tested. The test showed the battery was not holding a charge. Bought a new battery.

5) Also, purchased a new key switch. The key switch looked ok, but it was in-expensive so thought it better to replace it.

I’ll let you know in a month or two if this was the solution.

Thank you for all your assistance.


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## Bill Kapaun (May 8, 2007)

Your Voltage Regulator is bad.
It should be putting out well over 13 V.


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## Bill Kapaun (May 8, 2007)

BTW you SHOULD get 1.50 V on your penlight battery.
My point was to show how INACCURATE these cheap meters may be.
Expect all your DCV readings to be 8% high.


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