The International Cessna^® 170 Association

Well, I still don't know what was wrong with the charging system but it is working as-designed as of today. The connections were all checked and then another diagnostic was run on the system.

To test the alternator output, the field was connected directly to the hot bus which bypassed the controller.The engine was then run while monitoring the output current and voltage. Both remained steady at steady load and rpm and both varied directly with load and rpm which confirmed the alternator was operating properly.

Then the system wiring was returned to normal and the engine restarted. The alternator charged properly and continued to load and unload as system loads were added and removed. The plane was then flown trying to duplicate the previous flight's problems with the current fluctuating. During the entire flight, the voltage remained at 14.3 and the current was a consistent +1 or +2amps which is normal.

So, we still don't know what caused the problems but connections were probably the culprit. Nothing was done to any other part of the system and it went from not working at all, to working erratically, to working properly by just removing and reattaching connections. It remains to be seen if the problems will reoccur but if they do, we'll start over and figure it out. At least I have a better understanding of how the system works now.

I had a similar problem some years back. Everything looked ok, no broken wires that I could see, gentle tugs showed everything seemed to be secure. But a A&P friend stopped by to see what I was doing and started grabbing wires and giving them fairly good yanks and one came right out of the terminal end due to a bad crimp. Put on a new terminal and it's been working fine since. Could be a possibility.

Richard, its definitely Electrical Gremlins Glad it appears to be working properly.

As long as the gremlins don't start smoking, I'll be happy to deal with them if they come back.

Roesbery wrote:I had a similar problem some years back. Everything looked ok, no broken wires that I could see, gentle tugs showed everything seemed to be secure. But a A&P friend stopped by to see what I was doing and started grabbing wires and giving them fairly good yanks and one came right out of the terminal end due to a bad crimp. Put on a new terminal and it's been working fine since. Could be a possibility.

During the 2003 convention (Wilmington) poker-run, at the first stop is how I met Harold Holiman (who recently passed) ...
Harold was standing by his dead-on-the-ramp C-180 with no electrical, and his face lit-up when he saw me land and taxi up.
As I was handed my dealt-card, he asked me to take a look at his airplane, as it had a serious discharge occurring in flight and his battery was nearly dead.
He admitted that it had been troublesome for some time but on this fly-out it had finally died.

Dumb-luck intervened, as I opened his cowl door and saw he had an Inter-Av alternator conversion (with which I was familiar from my previous ownership of a C-206). I mindlessly grabbed the A-lead (primary output wire) and casually wiggled it and it parted from the ring-connector at the threaded stud.
Harold looked like he'd just witnessed The Resurrection!

We grabbed a pair of ordinary pliers, inserted the wire back into the poorly-crimped ring-connector and gave it a squeeze. He never had another problem with his charging system.

For the next several years, if Harold had so much as a low tire... He'd call me about it before he even grabbed a pressure-gauge.