Regulator problem on Starter/Generator - K181

[Cleaverkid 11]

Hey guys,

I've discovered a troubling issue with my 864 K181. If I increase engine speed much past idle lately, the Ammeter goes into a gyration swinging the needle almost peg to peg. Doing what little troubleshooting I know in the electrical world, I've discovered that the Delco-Remy voltage regulator mounted on top of the starter/generator is rather loose and only held on with one lonely small screw. It looks like there's another screw hole on the opposite side of the regulator strap but it's missing now. Could this be as simple as that thing loosing ground, or do I have something more serious going on?

Thanks for your help! You guys are the greatest!!! :thumbs:

[ducky 1]

i would try putting the other screw in and replace the other one withe the correct size and try it. if that dosent work try testing the r/r

[Buzz 502]

Here's some good info on regulators from the Simplicity site:

http://www.simpletractors.com/service/elec...cal_systems.htm

[Save Old Iron 1,568]

The regulator absolutely needs a good ground to the starter / gen case. A dedicated ground wire between the two is never a bad idea. Normally the ground is established with a mechanical (screw) connection between the metal cases of the two devices.

Also check under the regulator case. There should be a braided ground wire going between the mounting bracket of the regulator to the body of the regulator. Regulators can be "vibration isolated" with rubber mounts between the mounting bracket and the regulator case. Check to make sure that braided wire is intact so you have a ground to the actual case of the regulator. :D

[Cleaverkid 11]

Thanks for the replies guys. You've confirmed my suspicions about the rocking bracket loosing contact. Looks like I'm going to have to pull this Starter/Gen off the motor and get some screws in this. Unfortunately, my fat fingers just won't fit and bend down between the gas tank and the starter/generator to fix it while it's mounted on the motor!

I'll try to post results but probably won't be till Saturday evening.

Thanks again! You guys are the greatest! :thumbs:

[JUSS10 250]

just out of curiosity what is an 864? thought the only 8 horse they made in 64 was an 854 :thumbs:

[Cleaverkid 11]

An 864 would be an 854 to anyone who can type worth a hoot!

To this fat-fingered old guy, I'm happy that I'got the fact that it's an 8hp across!!!

Sorry and thanks for noticing!

[Cleaverkid 11]

Hey guys (or Chuck aka SOI),

Finally got around to working on this regulator issue last evening and it's now firmly grounded/mounted to the Str/Gen case. But when the engine is running, my ammeter still seems to bounce a lot. It's not as bad now and doesn't seem to bounce all the way from pegged NEG (left side of scale) to pegged POS (right side of scale)....just seems to bounce from neutral (middle of scale) to high POS. Am I looking at a bad regulator now? Got any other testing suggestions first?

Thanks again!

[Save Old Iron 1,568]

Joe,

thanks for the invite into technology that was "new" when I was in diapers. Good news though. I was able to show my wife this post and justify the 857 I bought a few weeks back.

"Look Dear, I was able to help out the guys, so the new tractor is really something I NEEDED to buy - TO HELP THE GUYS - Yeah , that's right".

Anyway, here are a few thoughts.

The ground connection resolved the wild negative to positive swings in the ammeter.

The key difference now is the swings are all in the positive (charging) direction.

The issue is probably the regulator, but could in fact be a partially dead battery.

The SG regulators are "full on, full off" type of controllers. There is no half power or partially on trickle charge.

The regulator makes 3 "electronic" decisions in order to keep the battery charged AND protect the generator unit from overheating / frying.

Decision #1

Let's look at the output voltage from the generator. If the voltage out of the generator is less than a "cut in point", (tractor not running or tractor is just starting up at low RPM's) , do not connect the regulator to the generator. Wait until the generator voltage rises above about 10 volts before you allow the regulator to control the generator. This decision allows the regulator to disconnect the battery from the generator to prevent the battery from being discharged when the tractor is turned off.

Decision #2

Ok, the engine is running and the generator output is above 10 volts - the regulator is now connected to and is able to control the output from the generator.

Now let's monitor the battery voltage to see if it needs to be charged. There is a "voltage monitor" relay adjusted to stop the charge current to the battery if the battery voltage rises above the "regulator voltage set point". When the battery voltage reaches 14.x volts, the regulator stops calling for generator output. Current from the generator to the battery (thru the ammeter) is reduced nearly to zero charge current. Not zero current , but close.

If the battery voltage drops down below a minimum voltage set by the regulator, the voltage relay energizes again and turns the generator on full blast again. Current from the generator goes full blast and proceeds to charge the battery back up to the "regulator voltage set point".

This cycle repeats and repeats while the tractor is running. This keeps the battery charged to 14.x volts.

Decision #3

While the regulator commands the generator to produce current, the regulator also monitors the amount of current flowing from the regulator (thru the ammeter) into the battery. Please remember the voltage and current limits are being monitored at the same time.

If the current demanded by the electrical system or battery exceeds a "maximum current flow set point", a different relay in the regulator opens up the field voltage to the generator and brings the charge current back down to nearly zero. This "maximum current set point" limits the generator output to its design limit (somewhere around 10 amps sounds about right). When the charge current falls below the max setting, the regulator slams the current back on again until the current thru the regulator again exceeds the maximum setting and then slams the current off again. Think of the current sense relay as a 10 amp self resetting circuit breaker that can cycle several hundred times per second. You may also think of this process as dimming the lights in your room by flicking the light switch on and off rapidly. No real dimming is taking place, just how long they are on versus off and thus a perceived change in brightness. Crude by today's standards but workable.

This full on / full off cycling is what you see in the ammeter indication.

Sooooooo............

either your regulator is toast, or needs adjustment

or

the battery is not capable of maintaining a charge and demands a constant charge greater than the 10 amps the generator can supply.

The regulator is slamming the current on to 10 amps then slamming off to nearly 0 amps when the 10 amp limit is exceeded. This "slam cycling" happens several times per second. This on / off cycling of current is the vibration you set in the ammeter needle. You can try this with your battery charger by connecting the + charger lead to the battery and then disconnecting and reconnecting it as fast as you can. You will see the battery charger ammeter jump the same as the tractor ammeter.

I would fully charge the tractor battery so little if any charge current will be needed to charge the battery when the tractor is running. With a fully charged battery, the regulator may need to drip in a small charge, tripping the over voltage relay in the regulator when the battery reaches 14.x volts. That's normal operation.

The charge current to top off a fully charged battery should be very small so the over-current relay should never have to engage in the regulator assembly.

Do a load test on your battery if the ammeter swings keep happening with a fully charge battery. The battery may charge to 14.x volts but it may not be able to keep the charge under load. Replace the battery if a charge cannot be maintained.

Sorry for the long post but I believe understanding how these systems interact allows you to understand why the ammeter is bouncing around.

This whole concept will make it into a future SOI University class. I find this crude type of voltage regulation very interesting. Apparently it was considered quite the advancement in charging systems while SOI was loading his diapers back in the 50's.

[Duff 206]

Dang, Chuck, you've got an incredible teaching style!

Thanks!

~Duff :USA:

[Save Old Iron 1,568]

Thanks Duff, just learned that myself last year from someone else asking.

I still think a picture is worth a 1000 words for this one.

I'll try to draw up a little diagram later today to illustrate this a little better.

I also have a module planned for the "Board of Education" that will show the whole process in action.

One of these days, the parts for this system are going to get scarce, then expensive then non existent.

Maybe thru a better understanding of the system we can help avoid replacing parts that are repairable and repairing parts that would normally be considered scrap.

[Cleaverkid 11]

WOW!

Chuck, you are the master!

I don't have a good way to "load test" the battery, but I will definitely try the full charge method first and see what happens. I'm betting your on to something anyway, because I noticed while working on this old girl that the battery I have in her is a Wal-Mart special with a date sticker in 2006! I didn't realize it was that old to begin with, so for $25, it's probably going to be replaced soon anyway!

Oh, and the "lesson" is defnitely worthwhile! Let me know when the next University semester starts and how much the tuition is....this one would be worth it!

Joe

[Save Old Iron 1,568]

I don't have a good way to "load test" the battery

Joe,

thanks for the update and the kind words.

A couple of words used here do not usually come up in the same sentence.

"Rapid" and "change " don't usually partner up with "good battery".

"4 years old" and "Wally World Battery" are not usually seen in the same sentence either.

I thinks its the old battery that's giving you the current symptoms.

I have said it before

Get one and use it - no excuses - will save you LOTS of troubleshooting.

http://www.harborfreight.com/50-amp-6-volt...ster-93784.html

[Cleaverkid 11]

Thanks again! I didn't realize I could pick up a load tester that cheaply. We only have one Harbor Freight store around here and it's about 15 miles from me so I rarely make it over that way. 15 miles in a small city is a long way!!! LOL

Yeah, I was rather shocked when I notice how old that battery is. I usually keep better track of those things, but this tractor is stored inside my garage, never below freezing except when she's pushing snow! And this is the first summer in about 5 that I had the mower deck mounted.

I'll let you know what happens after I charge it up this weekend!

Thanks again, my friend!