Not charging battery

[LawnWizard]

Trying to sort a charging issue on Ariens Max Zoom 60 / Kohler Courage Pro 25. Just acquired used. Dead battery. Former owner said the blades quit the the engine died. I assumed bad battery. Partially correct, battery would not take charge from charger. Replaced, started, ran great. Shut off, had trouble restarting. Checked voltage 12.6 at battery. Checked fuse (only found one 25 amp). Checked all battery connections. All tight, no corrosion. Checked voltage at middle wire of VR. 0V with key off / 0V key in run position.
Installed new VR. Still showed 0V key off but 12.5 key on. Checked AC volts on outside wires of connector = 40V AC with engine running. Started engine- still 12.45 coming back to batt. Retested VR now 0V on center wire key off or on. Also almost 0 with enrunning WOT. I'm assuming the new VR is fried? Question is why? And where is my open pos? If stator was bad, why 40V AC? Is there another fuse somewhere?
Any suggestions will be greatly appreciated.

 

[bertsmobile1]

Check that the VR has a ground
Usually the case is ground but if bolted into a plastic blower housing it needs a ground strap ( or two ) from a metal part of the engine .\
Remember electricity flows in a LOOP so there must be a connection to both +&-
To test the VR you unplug it then measure the voltage from the DC connector to the case
It should read around 13 V or better at full speed
Kohler use a brass strip that sits in a recess in the blower housing on a lot of their mowers to make the ground connection and after a while it cracks through or will fall out then the blower housing is taken off.
I make 2 ground wires and run them from different bolts to either side of the VR

 

[LawnWizard]

Check that the VR has a ground
Usually the case is ground but if bolted into a plastic blower housing it needs a ground strap ( or two ) from a metal part of the engine .\
Remember electricity flows in a LOOP so there must be a connection to both +&-
To test the VR you unplug it then measure the voltage from the DC connector to the case
It should read around 13 V or better at full speed
Kohler use a brass strip that sits in a recess in the blower housing on a lot of their mowers to make the ground connection and after a while it cracks through or will fall out then the blower housing is taken off.
I make 2 ground wires and run them from different bolts to either side of the VR

Thanks Bert.
The VR bolts onto the metal shroud just under the flywheel. I did make a seperate wire and attached to the engine block. I did a test with it unplugged, got 0.1 V DC at the center wire at WOT, 40+ volts AC on the outside 2 wires.

 

[bertsmobile1]

In that case the VR is shot

 

[LawnWizard]

Thanks Bert.
The VR bolts onto the metal shroud just under the flywheel. I did make a seperate wire and attached to the engine block. I did a test with it unplugged, got 0.1 V DC at the center wire at WOT, 40+ volts AC on the outside 2 wires.

In that case the VR is shot

I figured. Next step?

 

[StarTech]

I figured. Next step?

Well for most of us we replace the bad voltage regulator.

 

[LawnWizard]

Well for most of us we replace the bad voltage regulator.

Nice reply STAR! If you had read the op, I said I replaced the old VR with a new one. Now the new one test bad. Do "most of you" buy them by the case for one time use?

 

[LawnWizard]

In that case the VR is shot

Bert,
My understanding of the system is that the VR rectifies the AC current into DC then regulates it to +/- 14V DC to charge the battery. Without the VR plugged in, why should the middle wire show anything? Doesn't it work as a pathway to provide DC from the VR back to the battery? Also, according to everything I've read, there seems to be an open Pos to cause this situation. Can you think what it would be, other than a blown fuse? As stated, I can only locate one 25A. I would think that there would be a seperate charging safeguard somewhere, no?

 

[bertsmobile1]

If the VR is getting an AC feed then it will be converting it into DC even if the DC has nowhere to go
So the meter measures the POTENTIAL between the + and - , not the FLOW which would of course be Amps
Remember a voltage reading is just that , the electrical difference between 2 points
When connected to the mower then you are measuring the potential between the battery posts minus any voltage drop caused by bad/ dirty / corroded connections as the plug is connected directly to the battery , some times via the key switch
If you measured from one AC post to the engine ground then you would get a reading of 20V
This stuff should have been taught in high school science I know it is in OZ but it is amazing just how few understand any of it.
I have a side hussle with a friend to rewire old motorcycles called IR Wiring , the IR bit being Idiot Resistant as we use different connectors at every connection so it can not be connected wrong

Right now there is another poster trying to wire a 3 Amp alternator into a mower that requires at least 7 to work.
Despite being told twice it will end up in tears he is ardent that because the motor runs it will be fine
B & S put out a wonderful publication called "the Repower Guide" with everything you need to know about mower electrical systems & testing them.( google it )
In a tounge in cheek mannar Toro called their electrical manual "the Demystification Guide" because very few seem to be able to understand mower electrics .
And the tragedy behind all this there is almost nothing in a mower that requires a skill above 15 year old high school electrics apart from the sealed modules .