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I'll let y'all catch up with me:

I have an Ariens 46in lawn tractor with a 22hp B&S Intek V-Twin/Twin Cylinder engine. The model is: 407777-2217-G5. Bought the mower brand new in 2012, since then it's been having hard-start/no start issues. You'd turn the key and it would hesitate before turning over or sometimes you'd have to turn the key multiple times to get it to start. The battery is brand new replaced, the solenoid is getting 12.5V in and out to the starter. The starter checks out. Well every time you'd charge the battery after say 15 minutes, the engine fires up instantly. Therefore I know the issue must be with the charging system because the battery isn't being charged fully even though it claims it has 12.5v on the multimeter. As the service manual states, I have either a 10amp or 16amp charging system. The owner's manual says in the spec box that the charging system is: "16 @3600rpm" and I'm assuming 16 is amps. The output of the stator is only 16-17v AC but the service manual says it shouldn't be lower than 30v!!!! The only way to tell if it's a 10 or 16 AMP system (other than the owner's manual saying so), the flywheel magnets are small for a 10 amp and large for a 16amp. My flywheel has a ring of square magnets and IDK if that's the large or small. Either way even for a 10amp system the output is low(should be no lower than 20v). I replaced the stator with a brand new one from B&S and it still only gives me 18v. What is going on?

Check the charging system where it matters the most--at the battery.

Check the voltage of your battery with the engine off. Start the engine, rev it up. Check the voltage across the battery terminals again.

If the voltage is the same (or lower) your battery is not being charged. Typical value for a charged battery is ~12.7 volts. Typical reading for a working charging system is 13 to 14 volts. ( edit: A 12.5 volt reading with the engine running is not indicative of a battery being recharged.)

If it's charging, something may be draining your battery when the mower isn't being used. Most multimeters have an amp meter function that can check this by removing a cable from the battery (with the engine off) and putting the multimeter between the battery post and the cable. Amp draw should be zero or very close to it.

Another possibility is a bad battery that simply goes dead by itself.

And if it is not charging, check the earth strap on the rectifrier. It is the usual suspect.

cpurvis said:

Typical reading for a working charging system is 13 to 14 volts.

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So you're saying the 18v given from the stator is good enough at 3600 rpm even if it shouldn't be lower than 30? I'll check the charge on the battery with the engine running too.

And if it is not charging, check the earth strap on the rectifrier. It is the usual suspect.

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I shall look at that as well.

saltlife97 said:

So you're saying the 18v given from the stator is good enough at 3600 rpm even if it shouldn't be lower than 30? I'll check the charge on the battery with the engine running too.



I shall look at that as well.

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18 volts at the battery is actually too much. Batteries boil off their electrolyte if the recharge voltage is too high. 14 volts at the battery is more than enough to recharge 12 volt batteries.

cpurvis said:

18 volts at the battery is actually too much. Batteries boil off their electrolyte if the recharge voltage is too high. 14 volts at the battery is more than enough to recharge 12 volt batteries.

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The 18v AC is coming directly from the stator I mean. Before it enters into the rectifier to be turned into DC. The output voltage from the alternator is below the specifications mentioned in the service manual (30 volts at 3600 rpm).

That is all well and good, but what is the voltage at the battery with the engine running? That is what ultimately matters.

cpurvis said:

18 volts at the battery is actually too much. Batteries boil off their electrolyte if the recharge voltage is too high. 14 volts at the battery is more than enough to recharge 12 volt batteries.

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Only on a open toped flodded cell battery.
The maximum recharge voltage depends upon the state of charge of the battery and the chemistry of the grids and grid paste .
The current available and the current ( Amps ) rate of charge depends principally upon the surface area of the plates.

To charge properly you need both volts & amps.
Week magnets will always put out full volts as that is a function of the actual windings and the speed that the magnets energise the coils.
But it is very common to find an old Pommie motorcycle alternator that still puts out 14.5V but only at a paltry 2 or less Amps because the magnets have become weak. That is why we went to field energised alternators for general use & not permanent magnet alternators.

And as an aside, pressure valve regulated batteries are no where as sensative to over voltage as open topped batteries another good reason to spend the extra $ 10 on a sealed battery for mowers which do not have a particularly good charging regulating system.

I'll still check the voltage across the battery at wide open throttle, but could a defective regulator rectifier be the issue too? Like with the mower off, could the rectifier allow voltage to leak back through the rectifier and into ground?

As I said, 18 volts going into a 12 volt battery is too much. Open cell, closed cell, it makes no difference.

Once you figure out what is happening, then you can start diagnosing why.

cpurvis said:

As I said, 18 volts going into a 12 volt battery is too much. Open cell, closed cell, it makes no difference.

Once you figure out what is happening, then you can start diagnosing why.

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At W.O.T, the max charge of the battery was 13.82v. After shutting down the battery was flickering between 12.78 and 12.79 back and forth.

OK, it's charging.

Now, if you have a multimeter with an amp meter function, disconnect the negative battery post an put the multimeter leads on the now-disconnected battery terminal and the ground cable.

There should be no current flow at all but it may show a milli-amp draw. Anything higher than the milli-amp ranges shows that something is draining your battery.

If it shows little to no current drain, let it set a couple days and re-check the battery voltage. If it's down a few tenths of a volt, have the battery tested. Even a relatively new battery can be bad.

cpurvis said:

There should be no current flow

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There was no current flow at 10a, 200ma, nor 20ma. I'll let it sit for a few days and check the voltage then. Thanks for help so far guys

I forgot one other thing to check and that is to test the voltage across the battery with the engine running and all electrical loads on (mower, lights, and anything else you may have). This is to make sure the charging system has enough capacity to run all of that stuff and charge the battery, too.

Might be a bit tough with the mower running with the seat needing to be down, but I'll check it out thanks!

saltlife97 said:

Might be a bit tough with the mower running with the seat needing to be down, but I'll check it out thanks!

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Yeah, you'll probably need a helper monkey for this check. I have used weights in the seat before but don't recommend it. Keep your feet away from the mower, too!

As much as I hate telling people how to bypass safety devices, this is one time that you will need to do it.
From memory your seat switch is a pancake type with a keyhole mount in which case you rotate the switch and it will drop out ( may need some encouragement )
These get clamped closed then the mower things you are there so you access the battery without being on the mower, just remember to reconnect it when your are done testing.
The other pin types usually have one pair normally open & one pair normally closed so you will need either need to strap the plunger down with a cable tie or disconnect the switch and jumper the wiring pins.

Things seemed normal with the electrical loads on. Left it for almost a week and checked the batt voltage and it's at 12.58v which seems to be normal. So it should start up easily the next time I'll run it. I guess the best test is to wait and see if it'll hold up for a few rounds of lawn mowing and see if it starts strong every time. Could've been the stator after all

Update: The regulator has two blown open diodes. Think I found the problem.

Hmmmm....

In post #11 you said the battery was receiving 13.8 volts with the engine running, which is above the normal 12.7 volts for the battery. This indicates the battery is being charged.

Then two posts above you said things appear to me normal with the electrical loads on. I'm assuming the voltage was still in the 13-14 volt range during this test?

If those two conditions are true, I'm not sure what replacing the regulator is going to do for you. How did you test these diodes to determine they were blown?

cpurvis said:

Hmmmm....

In post #11 you said the battery was receiving 13.8 volts with the engine running, which is above the normal 12.7 volts for the battery. This indicates the battery is being charged.

Then two posts above you said things appear to me normal with the electrical loads on. I'm assuming the voltage was still in the 13-14 volt range during this test?

If those two conditions are true, I'm not sure what replacing the regulator is going to do for you. How did you test these diodes to determine they were blown?

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I forgot to mention I didn't do my load test right and with the loads on, the voltage was below the recommended specs. but I Did an ohms test and the meter readings indicated the diodes were stuck open

Testing diodes is beyond my ability, but is an ohm meter the right tool to test them? The way I understand diodes is that they will have very, very little resistance with voltage applied in one direction and almost infinite resistance when voltage is reversed.

My mistake you're correct. I meant resistance. Nonetheless I used the diode function on the multimeter and it read OL in both directions. That's how I know the diode is blown open.

saltlife97 said:

My mistake you're correct. I meant resistance. Nonetheless I used the diode function on the multimeter and it read OL in both directions. That's how I know the diode is blown open.

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If the diodes are open circuit then there will be no DC coming from the regulator as that is how the regulator turns AC to DC, the diodes only allow the power to go in one direction,

bertsmobile1 said:

If the diodes are open circuit then there will be no DC coming from the regulator as that is how the regulator turns AC to DC, the diodes only allow the power to go in one direction,

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There are four diodes in the regulator I have. I did this test with my older friend who knows everything about this system. I can't accurately describe what we did but I do know two of the diodes are open while the other two are good enough to allow some charge to go through but not all. Therefore giving it's giving a crappy charge to the battery.