1985/6 312-8 Battery charging system

[Yitzchok 4]

Hi, when its off and i test the battery its like 13v when its running and i test the voltage at the battery the numbers are jumping way up (up and down) (the meter on it is broken so i was using a multimeter but it is a cheap one so idk) it's going all the way up to like 45v what should i do?

[ineedanother 2,486]

Are you just randomly testing something or is there an issue or problem that you are trying to diagnose?

[gwest_ca-(File Mod) 12,267]

Some digital multimeters will pick up interference with the engine running so not any help with diagnosis.

Most older analog meters with a needle do much better. Perhaps you could borrow one or replace the original with an automotive style the same size. They are not that expensive.

[Achto 31,890]

8 hours ago, Yitzchok said:

i was using a multimeter but it is a cheap one so idk)

 

I you question your meter, test your meter at a known source. This should ALWAYS be practiced when testing AC voltage in your home.

 

Test you car battery for example, should be around 12.5v with the engine off and around 14v with it running. A bad battery in the meter can cause your readings to be off.

[953 nut 66,467]

7 hours ago, gwest_ca said:

digital multimeters will pick up interference with the engine running so not any help with diagnosis.

Gary has the problem diagnosed properly.  If you place the multimeter on the seat of the tractor it will be far enough from the engine to give a better reading.

[Yitzchok 4]

Two months ago i put in a new battery the last time i used it was two weeks ago. Last week i turned the key and nothing happened i got my (not) trusty (not) good old multimeter and it gave me a reading of 0.02v. Today i tried the multimeter on the car and it gave me good readings i jumped the mower and i tested it and it gave me the same jumpy readings in ac and dc i also tested it by the wires that go to the factory installed analog meter (that i removed because it was broken) to get away from the engine and it gave me the same readings (I'm thinking maybe that's what broke the meter) what should i do before i put in a new battery?

[pfrederi 20,646]

Run a jumper wire from the voltage regulator housing to the Battery - terminal.  See if you r reading improve.  A poorly grounded regulator will do strange things

[Yitzchok 4]

I don't know where the regulator is.

 

[953 nut 66,467]

If the Spec Number on your engine is 47812 or 47828 there is no voltage regulator. The engine has two electrical leads, one is a 3 Amp line with a small diode in it that serves as a battery charging system and the other wire is AC and supplies power for the lights.

        Not the best system in the world but that is what they went to after Cecile Pond sold the company to the bean counters.       

[Handy Don 16,743]

11 minutes ago, 953 nut said:

If the Spec Number on your engine is 47812 or 47828 there is no voltage regulator. The engine has two electrical leads, one is a 3 Amp line with a small diode in it that serves as a battery charging system and the other wire is AC and supplies power for the lights.

        Not the best system in the world but that is what they went to after Cecile Pond sold the company to the bean counters.       

This engine must be up to at least 2200 RPM to get the voltage up high enough to charge the battery. The low (3 amp) current assures that the battery doesn’t cook.

Also, since the lighting line is AC, any directly-connected DC-needing LED lights will likely flicker. Incandescent filaments work ok on AC. That said, since they draw much less current than incandescents, directly connecting a pair of LED headlights (with proper polarity) to the battery should be ok as long as you keep the engine revs up. 

[pfrederi 20,646]

27 minutes ago, 953 nut said:

If the Spec Number on your engine is 47812 or 47828 there is no voltage regulator. The engine has two electrical leads, one is a 3 Amp line with a small diode in it that serves as a battery charging system and the other wire is AC and supplies power for the lights.

        Not the best system in the world but that is what they went to after Cecile Pond sold the company to the bean counters.       

 

 

The 3 amp system on my 310-8 works just fine....

[gwest_ca-(File Mod) 12,267]

The electrical section describes how to check the 3 amp charging system.

 

[953 nut 66,467]

6 minutes ago, pfrederi said:

 

 

The 3 amp system on my 310-8 works just fine....

On my '86 312-8 I had to charge the battery from time to time, then again it wasn't the best battery in the world. 

[pfrederi 20,646]

Battery in mine lasted a few years and she is just a chore tractor  lots of starts stops no long operating periods../ Didn't care about the lights never used her at night..

 

[My_horse 120]

I noticed the volt meter jumping on my ‘00  314-8 the last couple times I mowed with it. It’s a replacement SunPro, as the original crapped out and always read 16+v. Even though the battery was getting 14. I kept the old one for some reason. 
 

I should clean the connections on the regulator and see if that stops the needle jumping. It’s not in a great spot a can easily get wet.
 

It always starts great and the electric lift works great though.