Altenator problem?

[NCScott]

Hi Guys
I thought my alternator wasn"t charging so I took it off and had it tested and supposedly it was ok.
The gauge doesn"t move at all. eventually the battery goes dead. Any ideas?

Thanks for the help
49 8n 12v

 

[Devious]

I am just saying what I would do next. I would load test the batt at a parts house that can actually test it right. Thats just me. Devious

 

[old]

What alternator?? Delco?? One wire or 3 wire?? All that info is needed to help us help you. You need a meter to be able to really tell you what is going on. With the tractor not running you should get around 12.5 volts at the battery and with it running about 13-14 volts. If either one does not read that way then you have either a bad battery or a bad alternator but with out more info hard to help you

 

[lha]

A clamp-on ammeter,clamped on the output wire from the alternator will tell you how many amps are going to the battery.Simply start the motor,clamp on the meter,set to amps[mine has two settings for amps],observe the needle,rev and idle the motor.This will tell you if,and how much it's charging,as it can't be hooked up wrong.---lha

 

[soqueu]

you alternator will not turn enough to excite the alternator to start charging. You need to add a positive feed to temporarily excite the one wire alt with a switch that disengages when released. this will start the charging process. if you were to keep the line excited after you turn off the tractor the battery will go dead.

 

[souNdguy]

only some 1-wire alts work like that. what you describe is part of a 3 wire setup.

all depends on the vreg.

and of course.. alt make / model.

soundguy

 

[Paul in MN]

Just a simple caution here. Most clamp on Amp meters will only respond to AC current. Because of the diodes in the alternator, it is putting out DC, but admittedly in some kind of pulse waveform. Thus the test for alt output is usually recommended to be the DC voltage test which is easily read by the common relatively cheap meters.

And yes, I know there is a clamp on DC ammeter, I finally have one made by Fluke. It is probably in the $250 price range.

Batt voltage with engine off should be close to 12.6 V and with alternator running and putting out as it should, it should read about 14 V. Measure across the batt terminals.

Paul in MN