Measuring ac voltage across battery
 

My cub cadet 1641 had an issue with an intermittent amp coming on when starting the pto. While trouble shooting I discovered the battery had an ac voltage across the terminals I changed the voltage rectifier and the amp light does not come on any more while starting the pto but I still have an ac voltage across the battery. Any thoughts on what is going on? Thanks in advance.

Bill.

How much AC? I will check my 1864 tomorrow to see what I have, for reference.

In the upper twenty’s I can’t remember the exact amount I am thinking it was either 23.6 or 26.3. When I checked what was going into the rectifier it was 30 something.

Your meter isn't working, or you aren't testing right. If you had 24-26vac across the battery, you'd fry the coil and a lot of other things....including the battery. Get a different meter and test again.

Just out of curiosity, use the same meter and see what it reads with the engine off....

12.5 volts dc. When motor is not running. I have to set the meter to read either either ac or dc voltage. I discovered the ac voltage by accident after checking what was the voltage was going into the the rectifer i forgot to switch it to dc and put it across the battery terminals to see what the voltage was was reaching the battery after the rectifier which was 13.5 volts dc. Once i switched it to dc.

Yeah..... ok. So, what AC voltage does it read with the motor off?? That's what I was asking......

0 volts ac.

The engine produces AC,, the rectifier kinda changes it to sorta DC,,,

When you feed the sorta DC to a lead acid battery, it will charge the battery,,
that is what you want it to do,, right?
so, you can read AC, especially with a digital meter.

If you want to feed pure DC to the battery, that can be done,, the new inverter will cost more than a 1641 sells for,,,

I am using a digital multimeter. So what I am reading is normal?

Like was said the rectifier isn’t putting out perfect dc.
Your meter is saying ac voltage cause it’s picking up pulsating dc.
If you could look at the output of a rectifier with an oscilloscope you could see it.
Charging a battery doesn’t require a lot of conditioning of the signal.