How to check 12V charging system

I have a JD 40 I recently converted to 12V and after about 2
months the battery goes dead. This has happened twice and
I?m not sure if the charging system is even working. When the
tractor is running and I take one of the terminal wires off the
battery the tractor shuts down. Should it stay running even
without the battery connected if the alternator is working
correctly? If not is there a way I can check the alternator to
make sure it?s charging the battery? Thanks!
Greg
 
Disconnecting the battery cable while running may damage alternator. Are you sure the alternator was good? Did you add a diode or idiot light to circuit to bleed off current so engine will shut off? If you added diode or idiot light, is it installed correctly?
Do you have voltmeter or ammeter in circuit?
No answers, just questions!
Most automotive shops can test alternator if you bring it in. Off or on vehicle. Chances are the weather is better now than the next time it won't start!
 
The alternator I ordered online from advance auto so I?m assuming it?s good? And nothing new was installed except for a new coil. I have checked the voltage while it was running and it did read 14v. Thanks to the quick responses!
 
(quoted from post at 22:33:20 10/17/18) The alternator I ordered online from advance auto so I?m assuming it?s good? And nothing new was installed except for a new coil. I have checked the voltage while it was running and it did read 14v. Thanks to the quick responses!

At the battery measure voltage.
Then start it up and measure voltage again.
You should see something like 12V then 14V +/- a volt.

Also, with switches in the "on" position but engine not running, is the back end of the alternator shaft area magnetic?. If yes, it is working but not getting to the battery.

Maybe resurface all connections at the battery and tighten.
Sometimes corrosion at the battery terminals can prevent the alternator from recharging the battery. But will arc when the starter is engaged and allow it to start and run.
Then eventually the battery is dead.
 
Disconnecting the battery cable while running it not a good way to check an alternator. Doing so will damage the alternator and if you where to get in line with the cable you take off and ground it can KILL you. Disconnecting it like that makes the VR got to max charge and max volts so it is putting out 35 plus amp which is 35 million time the amps it take to kill and max volts can be 90 plus which is more then enough to push the amp to kill you. Just plain and simple a stupid way to do it.

Correct way to check is a volt meter check and a magnet test. Battery volts should read 12.5 plus not running and 13015 volts running. Magnet test is simple also the back of the alternator center should be magnetic when running if not then it is not being excited as need to work
 
Gennys generate. Alternators need a source voltage at all times. No source voltage and they tend to go full field output and beyond.
so that 12V alt can put out 30/40 volts and about 250 amps That power surge can be enough to wipe out various electrical components.
Good luck. Now you get to really check the alt. did you fry it? oops.
 
12 volt conversion with generator or alternator? If alternator I've been told NEVER disconnect battery with unit running as uncontrolled high voltage can occur which can damage equipment or your health. Some internal regulators or a bad diode in an alternator can run a battery down if the unit is not started regularly. I've seen one that took about 3 days to run battery down on a super A Farmall and others that could set weeks and never bother.
 

If you disconnected the battery while the tractor was running there's about a 99% chance you fried your brand new alternator. It's probably junk now. You can either get another one or rebuild the one you have for under $20.00.
 
If he is getting 14v after he did the battery disconnect thing, the alternator is not "fried".

And for all that say doom and gloom if you do pull a cable off a battery while running...
Do you know if any of that actually really truely happened???
Or is it all hear say ???

I know for 100% fact that when the side mount cables get loose on my 1999 tahoe, the alternator does not charge the battery.
Thus meaning it is running as if one or more battery cables are not connected to the battery.
But when I go to start it, the amp draw will arc the micro gap and start the engine and run.
Why has none of the doom and gloom happened?
 
(quoted from post at 10:29:31 10/18/18) If he is getting 14v after he did the battery disconnect thing, the alternator is not "fried".

And for all that say doom and gloom if you do pull a cable off a battery while running...
Do you know if any of that actually really truely happened???
Or is it all hear say ???

I know for 100% fact that when the side mount cables get loose on my 1999 tahoe, the alternator does not charge the battery.
Thus meaning it is running as if one or more battery cables are not connected to the battery.
But when I go to start it, the amp draw will arc the micro gap and start the engine and run.
Why has none of the doom and gloom happened?
ecause many "experts" think one size fits all. Not even all factory fresh Delco 10SI units behave the same.....different regulator designs over time. Still not advisable to chance a transient voltage spike taking out electronic devices.
 
(quoted from post at 11:29:31 10/18/18) If he is getting 14v after he did the battery disconnect thing, the alternator is not "fried".

And for all that say doom and gloom if you do pull a cable off a battery while running...
Do you know if any of that actually really truely happened???
Or is it all hear say ???

I know for 100% fact that when the side mount cables get loose on my 1999 tahoe, the alternator does not charge the battery.
Thus meaning it is running as if one or more battery cables are not connected to the battery.
But when I go to start it, the amp draw will arc the micro gap and start the engine and run.
Why has none of the doom and gloom happened?

Yes, I have had it happen several times. I had it happen when I foolishly disconnected the battery to "prove" if the alt was charging because of advice I was given by old timers used to generator systems. I had it happen this summer when a loose connection on a starter on a DB990 with Delco 10si let go and fried the alt. I had it happen to a brand new Delco on a Case VAI when an Amish guy I lent it to un hooked the battery while it was running to "test it". Maybe it's not a 99% chance, but for me it's been about that. That's how I got into rebuilding alternators!

And it's not when you try to start it that the problems occur. It's when you're running along and that loose connection lets go and there isn't enough current flow to arc across the gap. Then, IIRC, it's the diode that pops. But hey, if you want to take the chance, have at it. I prefer to avoid having to replace or fix something I don't have to by taking unnecessary risks.
 
(quoted from post at 09:18:53 10/19/18)
And it's not when you try to start it that the problems occur. It's when you're running along and that loose connection lets go and there isn't enough current flow to arc across the gap. Then, IIRC, it's the diode that pops. But hey, if you want to take the chance, have at it. I prefer to avoid having to replace or fix something I don't have to by taking unnecessary risks.

Like I said, the battery terminal(s) routinely on my Tahoe use to (knock on wood) come loose all the time.
It would start but eventually the battery would run down.
No other consequences.
 

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