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Good evening guys. I'm having issues with a battery draw on my Gravely 260Z. It has a Kawasaki FH7521V 25 HP motor in it. It runs great when I first start it (I keep it on a trickle charger). However, after an hour or two of mowing, if I disengage the blades and try to reengage, it acts like it won't always reengage them. It doesn't have enough power to activate the blades again. I found a youtube video (https://www.youtube.com/watch?v=3Qt1ykP5ddc) to help troubleshoot the problem between the alternator and voltage regulator/rectifier. I believe the issue to be with the voltage regulator/rectifier, but just wanting to clarify before I order parts and make sure I did the testing correctly (I'm not very familiar with voltmeters). I believe the issue may have stemmed from when I jumped my mower with my truck potentially damaging the electrical system.

I've tested the stator as shown in the pictures below (should be 13 at idol and 40ish at full throttle). With the engine running at idol, I got a reading of 13.25 . With the engine running at full throttle, I got a reading of 33.

I tested the voltage regulator as show in the pictures below (should be 13-14.5 running full throttle). With the engine running at idol, I got a reading of 8.39 With the engine running at full throttle, I got a reading of -1.131 .

I tested the amps on the voltage regulator(should be 3-4 amps wide open). With the engine running full throttle, I got a reading of 1.28.

Based upon these findings, I believe it to be the voltage regulator. Please correct me if I've set the settings on the voltmeter wrong or am interpreting this improperly.

Thanks for your input!

If you are charging your battery every time you mowing might have a battery issue so check if good and your mowing is charging correctly might have a clutch that is failing and pulling to many amps and pulling all the battery juice out. Might even have a worn belt if it engages and takes a bit for the blades to turn and pick up top speed also might check the air gap on the clutch.

Ok. I'll look into that. I took the voltage regulator off and am going to have it tested to find out for sure if that's part of the problem. I did replace the battery last year thinking that was the issue, but the problem has persisted.

I should also note that I don't always leave it on the trickle charger. I haven't had it on there since the last time I mowed and it's reading 12.3 volts on the battery.

Leaning more to the clutch or belt unless the switch is bad. When you try to engage the pto with the motor off after you been mowing can you hear it engage the loud clank. What happens when you been running and you stop and you stop and engage the pto. Good clank to clutch slow to pick up blade speed smell burnt belt. Need just a bit more info and what mower is it on

It's on a Gravely 260Z. I can hear it trying to engage the blades, but acts like there's not enough juice. Sometimes it will engage again then other times I have to put it on the trickle charger and then it'll engage.

I would test the clutch. Make to check battery voltage before start and again after you start it should be a high voltage when running at wot. Check ohms on the clutch and do a draw test on clutch. Betting the clutch is going bad. Keep us posted.

Looks like the rectifier is toast.
Check the voltage, ground to power output in AC mode.
If you get a reading higher than the DC reading then a diode in the rectifier is recti fried.
I am not a lover of battery tenders cause this is exactly what they can do depending upon how the charging circuit is wired up.
Reading between the AC outputs you should get a bit more than double the DC charging voltage ~ 14 V DC.
Between either AC outputs and ground you should get 1/2 the AC output between them both
You should see no AC between the DC output and ground.

I had the voltage regulator tested and it tested good. I should probably mention that I had jump started the mower with my truck running one time. I'm wondering if that may have fried the alternator. Not sure what else the problem could be since the regulator is good.

The B+ prong on the regulator to ground with a volt meter should show battery voltage, So either your battery voltage is dropping lower than what is required to close the trigger in the regulator, or you have a bad wire between the regulator and the battery that could be the problem. Try hooking a wire directly from the B terminal of the regulator to the positive battery post and see what voltage you get with the engine running.

So evidently I've been jumping cars wrong all my life. What happens if you connect both positive/negative cables to the battery of the dead battery vs putting the negative to a ground on the vehicle that you're jumping? I'm leaning towards possibly a damaged alternator with the issue that I'm having with the battery draw. Gonna try and test it. Although I already tested it in the first post and it showed 33 volts vs the 40 that it should have.