Generator question from a Newbie

RUHokie · Dec 16, 2012

I don"t think my generator is charging my battery. I bought a new 6v battery from TSC yesterday and the 1946 H started GREAT! But, I can"t read any consistent voltage from the terminals of the generator, and when I remove the negative battery terminal cable, Big Red sputters and dies. I just spent $100 having new field coils put in the generator, so I THOUGHT the generator would have been tested thoroughly before they gave it back to me. Should I be able to read 6 volts at the generator posts or at the BATT terminal on the cutout?
Thanks in advance for any suggestions,
RUHokie

John T · Dec 16, 2012

The REAL test of a charging system is to what voltage the battery (an actual LOAD) rises when its running at fast RPM. The open unloaded output of a genny, although it should certainly be higher then 6 volts, dont tell you near as much as what happens when a real load is applied..Id expect a good 6 volt battery to read somewhere around 6.3 volts when the tractor is just setting, but when shes running at fast RPM Id expect it to rise to at least 6.5 to 7 or so subject to RPM and battery and genny condition.

Did you Polarize the genny prior to start up?? You should have.. Try that

If you run my Troubleshooting Procedure below, including the ground the field test in Para 5, it should help diagnose the problem. Polarize the genny,,,,,,insure belt is tight,,,,,,insure BOTH the genny and VR or Cutout relay are well grounded,,,,,,,,try to temporarily ground the gennys Field (FLD Post) when shes running,,,,,,,see if she charges then?????

John T
John Ts Charging troubleshooting

david hamblin · Dec 16, 2012

it is positive ground thanks dave

Bob M · Dec 16, 2012

Hey John T - You should also mention the tractor's ammeter - assuming it's functioning - provides a convenient, "real time" indication of generator/battery operation.

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Normal ammeter indications (with lights off):

Engine stopped: Ammeter hand centered at 0.

Engine running at slow idle: Hand centered on 0 (magneto ignition) or several amps discharge (battery ignition).

Engine running at governed speed (both mag and battery ignition): 5 to 15 amps CHARGE (ammeter to the right of 0).

Bob M

El Toro · Dec 16, 2012

Use a volt meter and with the engine speed at 1/2 throttle or better check the voltage across the battery terminals. If you only see 6 volts your battery isn't being charged. Also you should see voltage on the A terminal of your generator when your engine is running. I have my
hour meter connected to that terminal on my garden tractor's Delco S/G as it only powers the hour meter while the engine is running. You probably need to pull the generator and have it checked at a shop that repairs starters, generators and alternators. I had one of mine rebuilt several years ago with new bearings and brushes. Should last another 40 years. Cost was about $53.00. Hal

John T · Dec 16, 2012

For sure, good point, often times "dudes" dont mention any ammeter indications and talk about voltage instead so I "reply in kind" and figure maybe the old ammeters are rusted n stuck like most were when I bought them at auctions lol

Or they were replaced with automotive that had a 60 amp scale and barely moved grrrrrrr

In yearssssssssssss of buying literally hundreds of tractors at at auctions, very few ever had a good working charing system, no wonder I had to learn how to fix the darn old things before I could retail them grrrrrrrr

John T

jim warehime · Dec 16, 2012

Make sure you polarize the system and it is POSITIVE GROUND. Jim

Generator question from a Newbie

RUHokie

Member

John T

Well-known Member

david hamblin

Member

Bob M

Well-known Member

El Toro

Well-known Member

John T

Well-known Member

jim warehime

Member

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