Charging issues

[Jesse]

I have 1973/74 cub cadet I’ve put a new voltage regulator on and I’m in the process of getting a new s/g if it still doesn’t charge what would be the next option
It starts and runs fine but no charge

 

[mgonitzke]

I would get our your multimeter and a wiring diagram and do some troubleshooting. Randomly replacing parts is by far the most expensive way to solve electrical problems.

 

[Jesse]

I’ve ohmed most of the wires and they have all checked out but I’ll keep looking thank you
I’m more of mechanics of the engine but not knowing electric do I have to re-polarize the new s/g when I get installed ?

 

[kharvey]

Are you sure that the new VR is wired correctly?

 

[Jesse]

By the wiring diagram I have I believe so the bat lug goes to the Negative side of the indicator gauge the gen lug goes to the Selinod and the field lug is going to field term of the s/g I hope that is rite

 

[mgonitzke]

The starter/generator will polarize itself the first time you energize the start circuit (if everything is hooked up correctly). Is the wiring harness still original? Those cloth-covered wires do not age well.

 

[Jesse]

The harness is still original but I have not seen any brakes and I ohmed most of the wires and they ohmed out good

 

[digger]

I’ve ohmed most of the wires and they have all checked out but I’ll keep looking thank you
I’m more of mechanics of the engine but not knowing electric do I have to re-polarize the new s/g when I get installed ?

You have not mentioned what voltage you have at the S/G and at the battery, not running and running wide open.

 

[Jesse]

With the old s/g battery was 12.3 voltage regulator was low idle 11.2 high idle 9.2 on the field side of the s/g high or low idle 2.9

 

[mgonitzke]

What was the voltage across the battery with the engine off, idle, and full throttle? Have you load tested the battery?

 

[Jesse]

Voltage across the battery engine off 12.5
Voltage across the battery while running high or low rpms 12.3 I’m not sure how to load test the battery

 

[jbland]

re-polarize the new s/g when installed ?

 

[rfunk]

As has been discovered before,
1) try "jumpering" each wire with a good piece of wire while operating.
2) do a voltage drop test under operating conditions on each wire.
The OP mentioned that an old wire can frequently have good ohm readings without load, but due to internal corrosion/damage, can have high resistance/voltage drop under load. (I can't remember exactly who it was, but I believe it was a long-time member; I can't claim this for my own wisdom)

 

[bmader]

Just had the same issue with my cub 149, turns out the voltage regulator had rusted wires inside and one side of the field coil was burn't up. Got both items from Charlie at CCSpecialties ,rebuilt the s/g installed both and problem solved.

 

[Jesse]

Thanks rfunk I’ll give that a try I should be getting my new s/g in Friday and I already have a new voltage regulator in now my ? Is do I have to polerize the new s/g when I install it and bmader I’m glad your issue was resolved with just those I’m hoping for the same

 

[kharvey]

Also clean and check all ground wire connections.

 

[mgonitzke]

Voltage across the battery engine off 12.5
Voltage across the battery while running high or low rpms 12.3 I’m not sure how to load test the battery

Load testing a battery requires a load tester. I'm guessing you don't have one, so an auto parts store should be able to test it for you.

With the tractor running, temporarily ground the F terminal on the starter/generator. This will bypass the regulator and force full output. If that doesn't change anything, the starter/generator is bad. If it pegs the ammeter on the charge side, there is a problem with either the voltage regulator or the wiring connected to it.

 

[Jesse]

Load testing a battery requires a load tester. I'm guessing you don't have one, so an auto parts store should be able to test it for you.

With the tractor running, temporarily ground the F terminal on the starter/generator. This will bypass the regulator and force full output. If that doesn't change anything, the starter/generator is bad. If it pegs the ammeter on the charge side, there is a problem with either the voltage regulator or the wiring connected to it.

Do I have to disconnect the field line on the voltage regulator before grounding the field terminal on the s/g

 

[mgonitzke]

Do I have to disconnect the field line on the voltage regulator before grounding the field terminal on the s/g

No. By doing this, you are bypassing the regulator. Just don't do this for more than a few seconds at a time.

 

[deverett]

I just want to mention that 2 years ago I received 3 s/g in a row, for two 149 tractors that did not work from my local cub dealer I identified them as off shore built units because the terminal nuts were metric. The dealer made a phone call and then told me I had to specify OEM spec. They ordered that and my problem was solved. They came in with 7/16 us standard nuts