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I have a grasshopper 720K and i have to boost it with the charger each time to start it, i put a voltage meter at the battery and it shows it is charging low, about 11 - 12 volt. The only way that the starter will spin fast enough to start the motor is if i have the charger set on boost otherwise it turns very slow as if the battery is weak, i've taken the barrey in and had it check and it comes back fine????? been told there is a bad ground?? checked everything and repairs some worn wires but still have the problem, Is there a voltage reg. or a part that could be bad that would cause this to not charge the battery?? and if so what are the chances that this too would be the starting problem

Yes the 720 has a voltage regulator. Here's how to check out this problem...
#1 Start the GH up....what ever you got to do, do it.
#2 With it running, set your volt meter on the battery (of course on DC voltage)
#3 At half throttle you should be reading 12.8 to 13.7 volts.
#4 Now, work the PTO electric clutch.....should still read 12.8 to 13.7
#5 Shut down the enging AS you watch the volt meter....it should not go down to 12.5 no sooner than 30 seconds.
#6 Now restart it with NO HELP...If it voltage drops below 9.5 volts- You need a battery.
If you never get a reading of over 12.5 volts when running, start a charging system check.
If you need I can help you threw that....GoodLuck:thumbsup:

I'll give that a try, i do know that i will need to boost it to restart, i can run this unit all afternoon, stop for a break and when i hit the key the engine either turns slow or not at all, hook the boost to it and it fires right up???????? When i checked the voltage before i did so without running the PTO, it was just running at half throttle.

I had same problem last yr. turned out to be bad bat. bought new one and no problems since.note I don't have your model so I would do what cajun says because he has the expertise...russ

started the unit, run the voltage check, 13 volt with and without PTO running, meeter says charging system weak,,,,,,, hold down the button to put draw in the system and it reads weak?? turn unit off and the voltage stays at 13volts, hit the key again and it turns slow and clicks, hook the charger / booster to it, run the charger for a few minutes, still turns slow and then clicks from low voltage to starter, switch over to boost, wait two minutes, hit the key and off we go,,,,,, run the unit for over 2 hours, turn it off and the whole thing starts over again, had to go retrieve the booster.:frown:

A Battery can fail and still have voltage! Doing a load test IN the mower is a bad idea! The Stater/Alternator charges at about 5-12 amps.. So if you engaged the electric PTO the voltage would have dropped. This could be a starter worn out too, have it checked OFF the mower. If it looks good inside then the problem "IS" the battery. Replace it with a 230 CCA at least, a cheap-o battery won't work.

If you used an automotive load tester, they pull far more amperage than the typical OPE alternator can supply (15A in my Grasshopper versus 160A in my truck, for instance)...so it is a bogus test.

If you are only seeing 13V, it sounds (to me) like its not charging correctly...start by looking at the switch (bad contact) and the regulator (bad unit), those are the two biggest issues I have encountered. You can also test the output of the alternator at the source if needed.

I assume you have checked all the fuses???

I have the same prob. on a 1997 721 3cyl. Kubota gas, with 1800 hrs. on it. Have replaced in order, battery (biggest autozone had gold 800cca., )then took it back and swapped it for another new one, then did the same thing with an alternator, then a voltage regulator. new post bolts,cables look good, . steved, when you say the switch do you mean the ignition (key)? I checked fuses also. I am about to pull my hair out any other ideas? thanks, a lot.:confused2:

BTW, my meter says not quite 12 amps. after charging the battery completely. then it starts dropping till it dies.

12 Amps? How are you connecting the meter for this measurment?

The best approach for checking a starter problem and also helpful diagnosing a charging system problem is a Voltage Drop Test. A digital voltmeter is best for this. You can get a pretty good one for $22 at Sears.

Connect the meter, set up for VDC across each connection one at a time. With the meter connected hit the starter switch. You should not be dropping much Voltage across each connection. If you find a connection that is dropping more than a few tenths of a Volt, that is a weak link in the chain and should be dealt with. The connection across the starter solenoid secondary side will probably drop more than a few tenths. If everything else is in good order you might could stand to drop almost a Volt across the Starter Solenoid contacts.

Before doing any electrical testing, Check Voltage across the battery with engine off, then check it again with engine running at medium speed. With a properly operating charging system, you should see about 12Volts with engine off and 13.5 to 14.5 with engine running. If you are seeing the same voltage across the battery with the engine running as you see with the engine off, either the alternator isn't working or you have a bad connection somewhere in the charging system.

Hope this helps.
Larry

I just went through the same issue with my 725. First checked alternator voltage. Don't know what the specs say, but mine was in the neighborhood of 30-50VAC depending on RPM, so I called it good. Next, I checked external regulator and wasn't getting anything out of it. So I ordered a new one. However, when the new regulator came and I actually disconnected the old regulator, I noticed one of the spade terminals had come partially out of the plug (on tractor side). After testing the new regulator and verifying the system was charging correctly, I switched back to the original regulator which turned out was also working correctly.

So I've got an extra regulator now if anyone's interested. Replaces Grasshopper 185530, Kubota RP201-53710, 6 contact plug. $48 - PM if interested.

The voltage on my 725 still occasionally goes low. There's a little corrosion starting on my fuses, and by moving the fuse my voltage varies. So next I need to clean the fuse contacts and grounding points while I'm at it.