NAA Charging Question

[phil(va)]

54 NAA, original 6 volts, starts and runs good, new battery, voltmeter on battery when running shows 7 volts. However, ammeter on dash shows negative slightly. Meter is NOT wired backward. Any thoughts? Something I need to attend to, or just ignore it?

 

[old]

Volt meter as in a VOM hand held unit?? If yes good chance you amp gauge is bad. Or not wired in correctly

 

[Geo-TH,In]

If your ammeter shows discharge when your turn your lights on, there is a chance it's wired right.

Measure battery voltage before you start it. Then any voltage above 6.6v should charge battery. So your voltmeter may not be 100% accurate either. Just look for about a 1v or more increase in battery voltage. Keep in mind, generators need to spin faster to make more voltage. It may take a few minutes for the battery voltage it come up.

So rev engine, turn lights on and see if generator can maintain a higher voltage than what you had when engine wasn't running.

My experience is voltage regulators are big problems, next to brushes.

 

[souNdguy]

cheap digital consumer grade volt meter? or analog meter?

if you full field genny, does charge rate on volt meter and ammeter go up?

was your discharge/7v reading taken at idle? what about pto rpm?

post back

 

[phil(va)]

1,000 rpms. Yes analog V meter, pretty good one, not Harbour Frt.

 

[phil(va)]

Good quality VOM analog hand held. Ammeter bounces a little bit also, but bounces on negative side mostly.

 

[old]

Amp meter is bad or not wired as it should be but the charging system is in fact working

 

[phil(va)]

Yea i was thinking it might be the VR, assuming the ammeter is good. Battery at rest is about 6.3, and as I said, about 7 running at 1000 rpms. Tractor starts ok, but it is just one of those little worries and this time of year is a good time to work on stuff like that. I will check it further and post back.

 

[souNdguy]

Try full field, post back

 

[phil(va)]

To try full field, do i ground field on genny to frame? Will that bypass VR? Don't want to damage VR. Thanks.

 

[souNdguy]

Grounding the field on a naa very/Genny will burn it up.

Apply bat to field on naa+ units as they are B circuit

 

[Geo-TH,In]

The VR is around $30-40. My Jubilee, naa, is 12v. A alternator is about the same price. I love my 12v. Only problem is the starter bendix gets damaged more often. I found parts to 6 damaged bendix in bell housing.

If I were you either convert or buy a new VR, even if you don't need one now, some day you will.