Regulator Question

[MikesRJ 558]

Not sure if this should be asked here or in engines, but here goes ...

Kohler K241S-46636D on a '73 WH 10-8:

Is the tractor's Regulator (P/N:101450) regulated AC output, or is it true DC out?

[Save Old Iron 1,571]

i'm sure there will be additional questions, but to get the discussion started -

the true AC output of the engine stator is full wave rectified into a pulsating positive DC voltage which exceeds the voltage required to keep a lead acid battery fully charged.

The rectified DC pulses are fed into what amounts to a " 3 terminal DC voltage regulator" which samples its own output to maintain an output of around 14.5 volts +/- a little (internal non adjustable setting). The output of this DC regulator still has a small AC ripple riding on its DC output.

A lead acid battery in good condition acts a VERY large DC filtering capacitor and when connected at the DC regulator output, filters out virtually all the remaining AC component of the DC output from the regulator.

When the battery starts to deteriorate (higher internal resistance therefore difficult to supply current and spin the starter) the AC component on the DC output will rise slightly. When you measure the DC component at the battery leads, the battery voltage looks "low" because the DC component went down and the AC component went up.

If any of the internal diodes in the regulator fail , this will also cause an increase in AC component

I have a digital oscilloscope to capture these waveforms if anyone is interested in seeing whats comes out of a regulator circuit. I have done this type of troubleshooting on cars to isolate bad alternators but never on a garden tractor.

And NO - I don't think this will power a 1000 watt subwoofer system for your new tractor

Let me know if that does not answer the original intent of your question.

[MikesRJ 558]

:hide: Answers my question to a "T".

The reason I asked was because I would like to replace the 1156 head and tail light bulbs with LED 1156's (SuperbrightLED.com), and was wondering if a DC regulator would need to be added in order to use them (had the regulator been diode rectified pulsed DC). But, with your answer I have the original question solved, now you wouldn't happen to know the output amperage of the regulator would you?

Interestingly enough, after asking this question, I found in my own documentation the Wheel horse Electrical Service Manual - Wheel Horse Electrical Service Manual

But now that you mention it, I may still be considering that sub-woofer system. :scratchead:

[Save Old Iron 1,571]

Your welcome Mike - sounds like this will be an easy upgrade - I always loved the "purity" of color on the LED taillights.

It was raining today so I was able to take a o'scope capture of the output of the DC regulator on a C81 tractor.

What you see here is the AC component that rides on top of the 14 volt pure DC output.

You can see the AC component is less than 100mv (.1 volt AC). You can even see the small humps that represent each individual diode in the rectifier "contributing" to the output. If you had a bad diode in the rectifier assembly, the humps would be higher and you would be seeing a missing hump out of every 4 humps.

As far as the current limits of the regulator, its generally limited by the output current of the stator. You could have a 15 amp stator and use a 20 amp regulator and never stress the regulator. If you have a 20 or 30 amp stator and use a 15 amp regulator, you might overheat the regulator if you end up drawing over 15 amps thru the regulator. Wire up the LEDS, set the ignition switch to ACC and turn on the lights - look at the amp gauge and that will be your draw on the regulator from your accessories.

The current capacity of the stator is generally limited by the number of magnets on the underside of the flywheel. The more magnets, the higher the potential current capacity from the system.

Adding the LED taillights will probably LOWER your current draw thru the regulator.

An alternate suggestion - if needed - is to add a filtering capacitor from the 12 volt line to the taillights and ground the other end of the capacitor, A 1000 microfarad capacitor or larger rated 15 volts or more will give you computer grade DC volatge at your new inserts. Total cost about $1 - $2 more.

[WheelHorse_of_course 99]

What speed was the engine running when this trace was capture.

As the frequency goes up the noticeability of the flicker will disappear - in fact in most electronic displays the LEDs are strobe to cut the current draw.

I am sure you know this, but you need to limit the current to an LED with a resistor.

I would take 13.8 volts/0.x milliamps = the R value for a single LED. If the LEDs are in parallel multiply that the number of LEDs x the amp value and use that in the above equation.

I would wire it up and see if flicker is a problem.

If I ever get my Charger's hood back (increasingly unlikely) I plan on adding LED lights.

Best of luck.

[MikesRJ 558]

Since most led lights designed for automotive use are rated 8-26VDC, I would think they would be fine without the capacitor. And I seriously doubt that >100mV of AC ripple is going to be anything to worry about either. So long as I have 12VDC +/- 4VDC I should be fine wiring them up as the manual schematic displays. I have an original NOS headlight and taillight kit (PN: 7223) coming, so that should work out fine with either incandescent or LED setup. Thanks for all your help.

Oh, and dummy me! I found this HUGE black and white label on the side of the starters throw-out gear cover which says "This unit is equipped with 15 Amp ....." Duh!

Your welcome Mike - sounds like this will be an easy upgrade - I always loved the "purity" of color on the LED taillights.

It was raining today so I was able to take a o'scope capture of the output of the DC regulator on a C81 tractor.

What you see here is the AC component that rides on top of the 14 volt pure DC output.

You can see the AC component is less than 100mv (.1 volt AC). You can even see the small humps that represent each individual diode in the rectifier "contributing" to the output. If you had a bad diode in the rectifier assembly, the humps would be higher and you would be seeing a missing hump out of every 4 humps.

As far as the current limits of the regulator, its generally limited by the output current of the stator. You could have a 15 amp stator and use a 20 amp regulator and never stress the regulator. If you have a 20 or 30 amp stator and use a 15 amp regulator, you might overheat the regulator if you end up drawing over 15 amps thru the regulator. Wire up the LEDS, set the ignition switch to ACC and turn on the lights - look at the amp gauge and that will be your draw on the regulator from your accessories.

The current capacity of the stator is generally limited by the number of magnets on the underside of the flywheel. The more magnets, the higher the potential current capacity from the system.

Adding the LED taillights will probably LOWER your current draw thru the regulator.

An alternate suggestion - if needed - is to add a filtering capacitor from the 12 volt line to the taillights and ground the other end of the capacitor, A 1000 microfarad capacitor or larger rated 15 volts or more will give you computer grade DC volatge at your new inserts. Total cost about $1 - $2 more.

[zero 0]

:scratchead:

[Save Old Iron 1,571]

Mike.

Rolf makes a good point,

I ASSumed these were the LED assemblies that came up when I followed your link.

IF THESE ARE INDIVIDUAL LEDS that you are going to "bunch" together and mount in the tail light assemblies, that's a whole other story.

Individual LED's will need to be current limited - but if this is an assembly with an 1156 socket on it - the manufacturer has intended them to be placed in a 12 volt circuit. All is well.

Rolf, as I remember the engine was idling. If this was an automotive capture, you could figure out the speed of the alternator but with a stator type arrangement with varying numbers of magnets and number of windings in the stator, it gets a little tricky to back calculate speed. You could do captures of the primary or secondary ignition pulses and calculate engine speed.

As far as flicker - no - these pulses are happening about 70 times per second - and human persistence of vision does not allow us to see anything flickering that changes above 30 - 40 times per second - household incandescent bulbs flicker 60 times per second (120 VAC 60 HZ) and no one notices that !! Just like that strobe effect you mentioned on LED displays.

[MikesRJ 558]

You're both getting quite astray.

If I had my "druthers" I'd put a set of H3 driving lights in the front with a custom lens, but that's just me.

The bulbs I plan to use are 1156 based and are 30 LED forward and 360 degree jobbers, which are specifically designed to replace standard 1156 incandescents. They already contain a limiting resistor (I imagine it's in the base) and are plug-and-play. All I needed to know was if I was getting pulsed AC or straight DC at the key switch.

BA15 Dual & Single Contact High Power SMD LED Automotive Bulbs

15mm Bayonet base bulbs for tail/brake/turn light applications

1157 (BAY15D) - Dual Contact and Dual Intensity

1156 (BA15S) - Single Contact and Single Intensity

Select LED color to match vehicle lens color

12VDC operation

Available in White Red Amber

Found on this page: SuperBright LED's

Headlights:

Taillights:

[Save Old Iron 1,571]

We did our homework for you Mike, now let us play in electronics land a little.

Plus, Rolf started it !!

Just making sure the advice was appropriate for the task - we want everybody happy here.

Your all set with what you have chosen.

Plug them in and light up the night :hide:

[DrabHorse 2]

Nice info here guys, thanks for explaining it so well.

I can understand most electric / electronic and mechanical stuff and it will make perfect sense to me, but if I try to explain it back to someone else it will end up a complete mess. :hide:

[MikesRJ 558]

We did our homework for you Mike, now let us play in electronics land a little.

Plus, Rolf started it !!

LMA

Well thank you for doing your homework for me. Next time I might even ask permission to speak.

[Save Old Iron 1,571]

:hide:

Oh stop now - you do complete, exacting work on your restores - figured you would want complete, exacting answers to your questions.

Its all good.

:scratchead:

[MikesRJ 558]

Oh stop now - you do complete, exacting work on your restores - figured you would want complete, exacting answers to your questions.

Its all good.

Just figured one good yank deserves another. :scratchead: