8N Ammeter High Reading

[TCH]

I have a Ford 8N, 12 v conversion, and all of a sudden today the ammeter was pegged at 30+ amps charging. The reading decreased as RPM decreased, but was never less that 12 amps charging. What might be the problem? Thanks.

 

[Dell (WA)]

TCH.......ennytime you have suspected alternator problems, take yer alternator in to autoparts store for "free" checkout. Simple, eh? .......Dell, a 12V advocate for the right reason

 

[Dennisinponca]

Sounds like the alt. is doing its job, charge your battery and check it. Weak batteries tend to hold in there until the weather changes from hot to cold and vice versa.

After charging and it is hooked to the tractor, with the key off, have some one crank it while you measure the voltage across the battery.

This is called a dynamic load test. A static and more accurate load test can be performed by taking it into auto parts place.

A strong battery will not drop too low, you have to make the call on what is acceptable. I get worried if it drops below 5 volts.

 

[FLAcharlie]

Also, make sure all the electrical connections in that area are nice and clean and bright and tight !

 

[LarryT]

There could also be a short to ground in the charging system. Before I went too far I would definitely Check for one as if you do have one you could burn up the whole electrical system and I have seen batteries blow up and catch fire and if your in the neighborhood you could be severely injured if not killed and no one would want that so please be careful. Sincerely, LarryT

 

[Hobo,NC]

No need to take it off,,, its already mounted to a test stand, what is the voltage reading...

 

[36 Coupe]

Before I started doing my alternator repairs I took one to an auto parts joint.He said its charging ok,I said test it again.It had blown the caps off my Wife Olds battery.Tested again he found the regultor was shot.I noted than the original rebuilder didnt use heat conductive grease on the regulator surface.My wife came in complaining that her Chevy smelled funny. I smelled sulfuric acid when I opened the hood.Battery had all fill caps blown off and the battery case was bulged.Another magic alternator crapped the bed.She called me to say her 72 Plymouth wouldnt start at work.Found the battery low, found the alternator brushes shot. went to the local auto shop, got a set of brushes for 2.50.Put them in ,let the engine run till it charged the battery up good and left.The Chevy was starting funny on Monday mornings.She made a trip to vist her mother,car wouldnt start brother put in a new battery.Same thing happened when she got home.I was trying to get my hay in so I told her to get it checked at a garage in the town she worked in.Mechanic put on an alternator.Same problem on Monday.I did some checks and found a 1 amp current drain.This was on an 85 chevy no computer crap.Opened trunk and touched the bulb ,it was hot, on full time.Chevy parts man said take the bulb out, Ive got those trunk lites on hand they have been trouble.Im 73 but still a good mechanic and tv man ,they call them technicians now.BS

 

[TCH]

I can check it with a cheap VOM; will that be accurate ebough? Also, do I measure the voltage across the battery or somewhere else; and running or stopped? Thanks.

fyi I had actually just finished charging the battery before starting the tractor and then observing the high charging amps.

 

[Hobo,NC]

yes,,, why did you have to charge the bat if your alt is shove'n amps out the yazoo into it....,, a bad bat will cause all kinds of strange issues either a over charge are the rare under charge but it does happen.... gotta have a good bat to get a good reading from the alt...

 

[TCH]

I charged the battery because the tractor had been sitting for about 3 weeks (this is at my hunting property so I am not there all the time).

I was afraid to run the tractor more than a minute for fear of burning something up or a hydrogen explosion at the battery. Maybe I should just get a new battery before winter sets in anyway.

 

[Ramrod]

It could be working just fine. Your alternator is probably capable of making 66 amps, so it could just be charging the battery. Usually, when a 12 volt conversion is done, the ammeter is changed out to a voltmeter, which is a much better tool for monitoring an alternator.

 

[Hobo,NC]

What he said

 

[lha]

I've had similar experiences to those of 36 coupe.They're agravating and waste a lot of time and money.I've got a cable tracer,which is a good tool to have,it hooks one side to a circuit,the other side moves along the wiring until the beeplng gets louder and you find the prob.---lha

 

[TCH]

I measured the voltage to be about 22 volts -- took the alternator to NAPA and had it tested. It was found to be bad. I got a new one and everything works fine. Replaced ammeter with voltmeter as suggested. Thanks for everyone"s help.