12 volt neg ground Altenator output

I converted to 12v system about four years ago. everything good until today. Now only getting 12.1 volts at the battery. motor running. one wire at alt. get 27v from post and ground. I expected 12.8/13.2 at battery. amp gage not showing any movement. Any thought about this. maybe a diod in alt. Thanks

ArloInt,Take your alternator off and have it checked free at most auto part stores.

Are we talking about an N-Series Tractor with a front mount distributor or EI? I'd also get the battery checked. How old is it? The battery must sustain a full charge under load in order to supply the needed voltage and amps to crank engine and keep it running. Your starter/alternator shop can bench test the battery as well as the alternator. If a front mount dizzy, are you using a 6-volt coil? If so, do you have the external ceramic in-line 1-OHM resistor installed? If you are using a 12-V coil the resistor is not used. Either coil used requires the original OEM Ballast Resistor is used and the entire circuit is wired correctly. The ammeter not showing any charging could mean bad gauge too so don't jump to conclusions nor buy any new parts until you have performed a methodical root cause problem solving procedure. Get out your copy of "WIRING PICTOGRAMS by JMOR" and find your set up. Troubleshoot/verify the wiring with power off -battery is getting tested right? Use a test light or VOM set to continuity -never assume the wire colors are correct. Colors don't conduct electrons. On 12V switch-over jobs, as the generator gets replaced with an alternator, the cutout (on 9N and 2N models) and the voltage regulator on post-1947 models gets removed altogether from the circuit. Once wiring and battery are tested/confirmed to be correct, see how it runs then report back. If you have had it wired all wrong, you could now have a bad alternator, but it get tested first -don't guess ...

Tim Daley(MI)

"Now only getting 12.1 volts at the battery. motor running. one wire at alt. get 27v from post and ground."

The 27 volts from post and ground....I assume you mean the large post on back of alternator. The back post on alternator is connected via an unswitched route through ammeter and starter solenoid/switch to hot battery post. You should read near same voltage at both ends.

Your voltage readings sound like either a broken connection between alternator and battery, or you are using a digital volt meter that is normally erratic in presence of charging or ignition system electrical static.

I agree with getting alternator checked.

agreed.. and if it's bad.. you have your core in hand and can get your 29-35$ replacement right them and have it clocked correctly.

Alternately ( pun ), if you have an amp gauge, you can connect directly from charge stud of alt to battery and see if it's pushing current.

Ok Tim. thanks for responding back. Front mount dist. Took the alt to a shop this am, checked good. 70 amp output. 14v. also. reinstalled. checked all connections have only one wire which runs from the post (backside) of alt. I noticed when they checked the alt they pluged a two spade connector to the two spades on the side of alt. maybe I am missing some wiring. I followed the installation instructions. also this evening took alt to another shop and it checked good, which I thought it would.

any way wire from alt goes to ampmeter thru it to the same post as the positive battery cable. pretty straight forward. I will do contunity check on all wires tomorrow. Thanks for the ideas.

(quoted from post at 21:55:42 06/19/18) Ok Tim. thanks for responding back. Front mount dist. Took the alt to a shop this am, checked good. 70 amp output. 14v. also. reinstalled. checked all connections have only one wire which runs from the post (backside) of alt. I noticed when they checked the alt they pluged a two spade connector to the two spades on the side of alt. maybe I am missing some wiring. I followed the installation instructions. also this evening took alt to another shop and it checked good, which I thought it would.

any way wire from alt goes to ampmeter thru it to the same post as the positive battery cable. pretty straight forward. I will do contunity check on all wires tomorrow. Thanks for the ideas.

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ell then you must clearly recognize that there is a problem with a drop of (27-12.1)= 14.9 volts across nothing but short wires and connections! Get to looking.