Alternator charging

[Per]

Hei!
My RV-4 alternator will not give me battery charging. Have a new battery, new volltage regulator and the alternator is checked out by a professional to be in very good condition. Could it be the 2 Diods on the starter relay's or somthing else? Amp meter show Zero when nothing is turned on , if ti turn on the main light or any otehr item, the Amp-meter shows minus(-) Amp.

[N98HK]

I would start with the simplest solutions and work from there...Start with your battery connections - especially ground. There may be some corrosion, so disconnect and visually inspect. The next thing to check out is the alternator wiring. It my test well on the bench, but if you don't excite the field properly, you won't get any charge. The other issue may be the wiring at your ammeter. Do you also have a voltmeter? Does voltage jump up from 12 to 14 when you turn on your alt? Review any schematics you have and verify every wire in the system. I've had my fair share of "how the **** did I put that wire there" moments!

[frankh]

Definatly check to see if your battey volts goes to 14V when it starts...I bet it isn't.

Also check that your getting 12V at the field coil....Pull the plug off the back of the alt....Should be zero volts on the terminals with the master switched off...turn the master on and one of those should go to 12v.

This voltage excites the field coil...I.e turns the alternator on....No volts means alternator won't come alive.

Check you actually have a ground connection between the case of the alt and the enigine block (actually the -ve terminal of the battery)....I.e should be close to zero ohms when you poke one test lead on the engine case and the other on the alternator case...

Sounds obvious but bonehead here painted his alternator mounting bracket which only gave a partial connection...It confused the snot out of my poor GNS 430 and made it impossible to fly in IMC...When I turned off the alt the GNS was happy...Ah hAh...well sure enough no ground between alt and engine block...DOH!

Frank

[Norman CYYJ]

You said that when the engine isn't running that the amp meter reads 0 that is good, you said that it reads negative when the engine isn't running when things are turned on, that also is good and it should. If it reads zero when the engine is running that also can be good. That usually means the battery is in good condition. If you turn on everything and it still reads zero that is good your alt. is charging enough to make up for the heavy current drain, if it goes positive then it is not only supplying enough to make up the power being used it is charging the battery. Doesn't sound like you have a problem. If you want to read what the alt is putting out all the time put the amp meter in series with the alt line, but it will never read negative in that position unless you have a major problem with the alt. A volt meter will usually be more useful then an amp meter.