Charging Voltage to high?

[moe1965 738]

Hello all.   I have a 1985 312-8 I've been working on. I checked the voltage while running with a volt meter and I'm getting a reading of 16.40 volts is that to high?   If so what do I need to replace.    Thanks in advance 

[cafoose 3,355]

Verify reading with another voltmeter, preferably an analog meter. Sometimes on these horses a digital meter can be inaccurate. Don't rely on a dash mounted meter. They are often not accurate.

If the reading is still high after verification then in most probability the regulator is not properly grounded or needs to be replaced.

 

[gwest_ca-(File Mod) 11,046]

1985 has the 3 amp unregulated but rectified charging system.

Designed to not overcharge a battery but it does happen.

Is the battery old and tired? If it does not want to take a charge the voltage can go high.

The charge current is rectified by a single diode. One can add diodes in series to reduce the voltage by about .6 volt per diode if no other cause is found.

[moe1965 738]

Thanks for input where would the voltage regulator be located and what would it look like.   Battery is about 6 moths old 

Edited June 4, 2022 by moe1965
More info

[gwest_ca-(File Mod) 11,046]

This is for a different application but a good description of how they work. Click on the pictures.

Down near the engine is a connector with 3 wires in it I think.

On the engine side of the connector one wire will have some tape covering the diode. That is the charge wire. Feel through the tape for a 3/16" x 3/8" bulge of the diode.

 

A simple way to reduce voltage is to burn some amperage by turning on a light or lights when the voltage gets high - if in fact it is as explained earlier. Best to try an analog meter with a needle if you have one.

 

If you had an electric pto clutch you could remove a drive belt and run with the clutch applied but your clutch should be manual.

 

A 12 volt cooling fan blowing on you may be an option - a Wheel Horse with climate control for hot days.

 

[Jeff-C175 7,202]

6 hours ago, moe1965 said:

getting a reading of 16.40 volts is that to high?

 

Where exactly are you measuring this voltage?  What instrument are you using to measure it?

 

It's not highly likely that a 3 A charging circuit could push a 6 month old battery that high, so your measurement is suspect.

 

 

[moe1965 738]

I'm measuring the voltage at the negative and positive post of the battery with the engine running. I'm using a craftsman volt meter

[Jeff-C175 7,202]

16 minutes ago, moe1965 said:

at the negative and positive post of the battery with the engine running. I'm using a craftsman volt meter

 

Well... that should be accurate enough!  When you measure with the tractor NOT running, after the battery has not been charging for a few hours, what does the meter read?

 

 

[953 nut 55,298]

3 hours ago, gwest_ca said:

A simple way to reduce voltage is to burn some amperage by turning on a light or lights when the voltage gets high

Gary,       the lights on this model are AC, don't think this would work out.

[953 nut 55,298]

1 hour ago, moe1965 said:

measuring the voltage at the negative and positive post of the battery with the engine running. I'm using a craftsman volt meter

Some times a digital meter will pick up a bit of stray induced voltage from the engine's electrical system. Locate your meter as far from the running engine as you can.

Also,  be sure that the terminals on your ignition switch and plug are clean and tight, a bit of corrosion could cause a false reading.

[moe1965 738]

Thanks again for all info.   953 nut I'll try what you said tomorrow and report back.   Voltmeter on tractor says 14 volts  on guage but my volt meter is giving a different reading.  I don't want to cook the battery 

[gwest_ca-(File Mod) 11,046]

14 minutes ago, 953 nut said:

Gary,       the lights on this model are AC, don't think this would work out.

I recall when SOI was with us someone replaced their rear reflectors with 2 clearance lamps using incandescent bulbs with a separate switch to lower the voltage as necessary to a safe level.

[953 nut 55,298]

           So perhaps the AC lighting power and the diode are fed from the same stator.

[gwest_ca-(File Mod) 11,046]

2 hours ago, 953 nut said:

           So perhaps the AC lighting power and the diode are fed from the same stator.

I believe they are but adding a load to the AC unrectified side should not affect the DC side.

The added tail lamps were powered by the DC rectified side or battery to lower the voltage.

[Jeff-C175 7,202]

It's very possible that the meter reading is in error.

 

Even though the charging current is in fact DC, the fact is that it's HALF WAVE RECTIFIED or 'pulsing' DC, and this could throw an inexpensive digital meter a curve ball and cause it to report an incorrect reading.

 

I wonder what a Fluke 87 or 89 would show.

 

 

[moe1965 738]

I cleaned the terminals by the ignition switch and never found anything in line like a dioed  it's charging a 16.60 now. Voltage in battery after sitting for a while engine not running is 14,40  

Edited June 5, 2022 by moe1965
More info

[Jeff-C175 7,202]

43 minutes ago, moe1965 said:

Voltage in battery after sitting for a while engine not running is 14,40  

 

I suspect your meter is not telling the truth.  A battery that's been sitting a while would read around 12.5V, or possibly into the low 13s.

 

 

[tunahead72 2,424]

4 hours ago, moe1965 said:

... Voltage in battery after sitting for a while engine not running is 14,40  

 

How long is "a while"?

 

[moe1965 738]

15 minutes     to answer tunahead72 question....   I'm in a real bad situation now. I may have crossed some wires.  I removed the plug in I'm thinking factory  plug that was original to the engine that comes out of the engine from behind the flywheel.  And replaced it with a new plug because one terminal was broken and the others didn't look so good.  The picture is the wires that are coming out from behind  the fly wheel which wire goes to what . Right now the single black wore I have going to the positive side of the coil the other black wire I have going to the back of the ignition switch and it is labeled    I.   For ignition I'm presuming. The yellow wire is going to the back of a switch that turns lights on and off.   Is this correct   for what ever reason I blew a fuse and now I have no spark... I'm an idiot 

[moe1965 738]

Up and running again for now back to the same issue of overcharging.     Gremlins tomorrow may be another issue 

[Jeff-C175 7,202]

2 hours ago, moe1965 said:

15 minutes     to answer tunahead72 question....

 

Not really long enough.  Let it sit overnight and check it in the morning before you start it.

 

 

[Jeff-C175 7,202]

2 hours ago, moe1965 said:

I'm an idiot 

 

Me too, don't feel bad!  We've all been there.  You're in good...??? company !  

[Skipper 1,788]

One easy option to all this could be to just mount a 10$ "kohler" rectifier, and be done with it. Simple rewire. That is if it is not just the handheld meter that is wrong. Try it on a car! Should say very close to 14.4v running engine.

[moe1965 738]

Voltage this morning was 12.60 on the battery with engine not running. I will put a rectifier on it . which line would I splice it into.   

[pfrederi 17,741]

I do not think you can just "add" a rectifier.  The stator used for your 3 amp unregulated system is different than the ones for 10 or 15 amp regulated systems.  Your stator would be #10  (10 and 15 amp system use 3 or 4)

Edited June 6, 2022 by pfrederi