Just replaced my dead alternator with a rebuilt unit from aircraft spruce. Now the issue is the Ammeter is swishing/erratic or “semaphoring”most of the time the engine is running. Any thoughts of what’s amiss?
Thanks.

Did you replace the voltage regulator too? I’ve seen them do erratic things on their way out.

CenterHillAg wrote:Did you replace the voltage regulator too? I’ve seen them do erratic things on their way out.

No, I didn’t. Is it common to replace them as a pair?

If it’s an older regulator it certainly wouldn’t hurt, I had a similar experience and solved the issue with a new regulator.

Check the field sense connection. Otherwise, it can be the solid state regulator was marginal at best.

Check all your connections. I had a similar problem, thought I isolated it to the voltage regulator connector but it turned out to be loose terminals on the battery. I apparently didn't snug them down after an annual. doh.

Overvoltage sensor was the problem with mine.
Replaced it and steady now.

All of the above. Start with the free stuff like checking all of the connections for loose terminals. If you find one, make sure the metal is clean since that gap can introduce moisture or small arcs. Give the connectors a good visual inspection for corrosion as well, while the components are usually fine the ring terminals can rust. Replace any you find that aren't in good shape. You should also check the output voltage of the regulator (should be doable on the ground, use extreme caution or get qualified help).

If your previous alternator failed, it may have also damaged the regulator (or vice versa). These are surprisingly fragile components that work well when they work, but when they break it can affect downstream parts and they are intolerant of bad power. Start with the simple stuff and work your way up though.

Just visited with a friend, commiserating that once again his 182RG is in the shop. A new Plane Power alternator was installed at annual, but not a new regulator, so there's insufficient charging of the battery. Apparently the failing alternator affected the regulator, so a new one had to be ordered. We discussed the same things as in this thread--connections, battery, over voltage, under voltage, bouncing ammeter.

That's why we have idiot lights in cars, so that we can't see bouncing ammeters. If it starts, all is good, right?

Cary

One thing you might try, after checking all your connections. Most regulators have a voltage adjustment. On many of the really old ones this was a electromechanical points thing, but in the 60's they went to a solid state version. The usually is a hole with a rubber plug, which you pry off. Use a non-metalic screwdriver like rod to fit into the slot head of the potentiometer that is inside the unit. hook a meter to the system and run you engine. Adjust it to read 13.5V or what ever is called out for in your manual. It may be cycling due to an incorrect voltage regulation setting for the new alternator. If it works, may save you a dollar or two. One other often neglected item is the noise capacitor, it is supposed to let that mild screaming noise the alternator makes on your radio get filtered off to ground. Bad capacitors cause some unpredictable issues with an electrical system. Nothing to lose by trying.

The connectors that hook up to your alternator do take a beating from vibration, I have had what looked like good spade connectors be just loose enough to make casual connection. So replacing them with good solid spades and solid non-corroded wire connections can make a world of difference.

colopilot wrote:All of the above. Start with the free stuff like checking all of the connections for loose terminals. If you find one, make sure the metal is clean since that gap can introduce moisture or small arcs. Give the connectors a good visual inspection for corrosion as well, while the components are usually fine the ring terminals can rust. Replace any you find that aren't in good shape. You should also check the output voltage of the regulator (should be doable on the ground, use extreme caution or get qualified help).

If your previous alternator failed, it may have also damaged the regulator (or vice versa). These are surprisingly fragile components that work well when they work, but when they break it can affect downstream parts and they are intolerant of bad power. Start with the simple stuff and work your way up though.

SUCCESS! In examining the wiring from the firewall to the alternator just about every single wire had crack/missing insulation. Applied shrink insulation in some areas and in others replacing terminal ends and whole wire sections. Started up engine, ammeter rock solid showing initially halfway from “0” to charge and settling down within a min to just the “charge” side of “0”. Thanks for all the advice guys, gotta love cheap, common sense fixes.

You might think about some fiberglass sheath material for the wires. Chafe and heat resistant.