How to see if a genertor is working?
Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=134451
Printed Date: 06 Nov 2025 at 11:26pm
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Topic: How to see if a genertor is working?
Posted By: nowaktj
Subject: How to see if a genertor is working?
Date Posted: 30 Jan 2017 at 12:15pm
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Hi guys-In the past, I have checked to see if a generator is working by hooking up a volt meter to the battery and see if the voltage increases with the tractor running. Is this a valid way to check one on a tractor? Like you hear your thoughts....thanks. ------------- D19D, D17D, WD, WC, Snobee, #83 Plow, SC Blade, 14' disk, 400 series planter, B , Terra Tiger, M Dozer w/Baker Blade, TL-12, 42S Grader, G |
Replies:
Posted By: Stan IL&TN
Date Posted: 30 Jan 2017 at 12:19pm
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I would use a DVM and measure resting battery without engine running. Start engine and give it a high idle and measure battery again. It should be higher if it's working. ------------- 1957 WD45 dad's first AC 1968 one-seventy 1956 F40 Ferguson |
Posted By: DrAllis
Date Posted: 30 Jan 2017 at 12:20pm
| There's a reason Allis-Chalmers had an ammeter on the tractor.......it tells you if the charging system is working or not. |
Posted By: Dusty MI
Date Posted: 30 Jan 2017 at 12:24pm
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Another way is remove the fan belt, then remove the cutout relay cover and push and hold the contacts closed. The generator then should run like a motor. Dusty ------------- 917 H, '48 G, '65 D-10 series III "Allis Express" |
Posted By: tadams(OH)
Date Posted: 30 Jan 2017 at 2:17pm
| Start the tractor then unhook the battery. If generator is working it will keep running, this won't work if you have a mag. |
Posted By: ctbowles 58
Date Posted: 30 Jan 2017 at 7:45pm
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Ground the Field (F) post on the Generator to the frame of the tractor, if it charges on the gauge then your Gen. is ok if not then the Gen. is bad. 0
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Posted By: DennisA (IL)
Date Posted: 30 Jan 2017 at 7:57pm
------------- Thanks & God Bless Dennis |
ctbowles 58 wrote:Posted By: DougS
Date Posted: 31 Jan 2017 at 5:16am
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Do the above, but put your volt meter on the BAT terminal of your generator. The voltage should increase from about 12.5 to 14.5 volts when you ground the F terminal. Otherwise you may have a wiring problem or a bad ammeter and you'll be spending $$ on the most expensive part first as you troubleshoot. |
Posted By: Gerald J.
Date Posted: 31 Jan 2017 at 9:21am
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DougS that BAT terminal is NOT on the generator, its on the regulator. An ammeter test is fairly easy. Before starting the engine turn on the ignition and the lights and if the points are closed and the lights aren't run from an L terminal on the regulator the ammeter will show a discharge. Then if it shows charge when the engine is running at a fast idle the generator is working. A generator generally does not charge at engine idle. If the voltage regulator is regulating well, the charging current will taper in time, depending on the generator current capability, down to zero current. It may take hours of running. Ammeters have been known to fail from rusty pivots. The meter movement is not high horsepower or torque. Gerald J. |
Posted By: Steve in NJ
Date Posted: 31 Jan 2017 at 10:04am
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Take it off, bring it to a local rebuilder and let him run it through some standard & load tests on his machine. This way you know whether or not the unit is working properly as it should through normal charging as well as when it has a load put on it. In most cases it only takes a few minutes and most rebuilders (like myself) don't even charge ya. If there's an issue with it he'll be able to fill you in on what its doin' and not doin'. Steve@B&B ------------- 39'RC, 43'WC, 48'B, 49'G, 50'WF, 65 Big 10, 67'B-110, 75'716H, 2-620's, & a Motorhead wife |
Posted By: nowaktj
Date Posted: 31 Jan 2017 at 11:50am
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I should have clarified. This is a 1935 M crawler that I have converted to 12 v using a starter/generator off of a lawnmower (has to use this as it spins opposite of most generators). I think I have it wired correct and think I have the correct voltage regulator on it...but to prove it I will run the test you guys suggested. Thanks. ------------- D19D, D17D, WD, WC, Snobee, #83 Plow, SC Blade, 14' disk, 400 series planter, B , Terra Tiger, M Dozer w/Baker Blade, TL-12, 42S Grader, G |
Posted By: Gerald J.
Date Posted: 31 Jan 2017 at 4:14pm
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After taking the generator to a test shop its crucial to flash it before starting to be sure it builds voltage with the proper polarity to match the battery. Gerald J. |
Posted By: Brian Jasper co. Ia
Date Posted: 01 Feb 2017 at 7:50am
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Grounding the F terminal while running is a quick test. If it wasn't working but works this way investigate the F circuit between the generator and regulator. For the sake of discussion I'm going to assume negative ground. To test a generator remove the belt and unhook the F terminal on the generator. Using a heavy run battery positive to the A terminal on the generator. It should spin fast like a motor. While motoring ground the F terminal. It should slow down but continue to motor. if these tests pass, time to test the wires. Using a headlight bulb, use each wire in a circuit to light the bulb. Bright light = good wire. If the wires test good, test the battery terminal wire with the bulb. Bright light = good. If it still doesn't work, make sure the regulator has a clean ground. Buff off any paint or rust making sure there is a good electrical connection back to the battery negative. Still doesn't work, replace the regulator. With any generator you should polarize it before starting the engine. When you do the motor test it is polarized at that time. If you install a reman or otherwise unknown unit, a momentary jump between the battery terminal and A terminal at the regulator does the job. ------------- "Any man who thinks he can be happy and prosperous by letting the government take care of him better take a closer look at the American Indian." Henry Ford |
Posted By: Lon(MN)
Date Posted: 01 Feb 2017 at 4:37pm
| Take it to Neil. He needs help getting the tree out of the pond anyway. |