Alternator / Battery?

[Monty]

Hello all. I was flying home yesterday and my battery started to overcharge. Voltage rose to high 14's and just entered low 15's when I decided to cycle my battery master. Shortly after turning my battery back on, my dynon VPX faulted and alternator turned off. Returning to home field I have inspected alternator wiring, etc and tried another start. Initially at lower power settings everything was working fine. Shortly after getting airborne the alternator/VPX faulted again. Is there any chance these indications could be a result of a bad battery? The alternator was replaced last year and I am finding it hard to accept that alternator failed this quickly. Any thoughts would be appreciated.

 

[Carl_Froehlich]

Buss voltage going high cannot be from a bad battery. Only your alternator drives voltage when it is about the battery open circuit voltage. Your alternator or alternator voltage regulator has gone south.

What alternator are you running and voltage regulator are you running?

Carl

 

[airguy]

What was the VPX fault? If it's overvoltage, Carl is right, there is only one source for that, it's the regulator or the "sense" wire feeding bus voltage sensing to the regulator.

 

[Monty]

Thank Carl and Airguy. I have an internally regulated alternator. I looked at the sense wire and it seems intact at the connection point. The internal wire bundle also seems good. I am looking at B&C alternator for replacement. IO-520 motor. Anything else I obvious I could be missing on the sense wire? Really appreciate the comments as I figure this out.

 

[rjones560]

Hello all. I was flying home yesterday and my battery started to overcharge. Voltage rose to high 14's and just entered low 15's when I decided to cycle my battery master. Shortly after turning my battery back on, my dynon VPX faulted and alternator turned off. Returning to home field I have inspected alternator wiring, etc and tried another start. Initially at lower power settings everything was working fine. Shortly after getting airborne the alternator/VPX faulted again. Is there any chance these indications could be a result of a bad battery? The alternator was replaced last year and I am finding it hard to accept that alternator failed this quickly. Any thoughts would be appreciated.

What kind of alternator? Some of them have a bad reputation for failing early. The B&C are a little more, but they last to TBO and will go another TBO with an overhaul. If it is a Plane-power I am not surprised at the failure. You want top quality accessories if you don’t want the aircraft to leave you stranded on the road.

 

[Carl_Froehlich]

Assuming this all worked at one time, then:
- The “source” connection to the alternator for buss voltage might have a bad connection.
- Odds are the internal voltage regulator has gone south. Search the VAF post on Plane Power for part replacements.

Carl

 

[soarhead]

Like mentioned above, it doesn't sound like your battery but I would suspect the voltage regulator. You mentioned it is an internal vs remote regulator. One thing to consider, they do not like heat. I had one go south and since putting a blast tube to the alternator cooling fans, have never had another issue. If you are getting high voltage in the future, consider turning off the alternator rather than the battery master. Your system will be happier.

 

[Tom broadhurst]

What kind of plane is your IO 520 in

 

[Tom broadhurst]

What kind of plane is your IO 520 in

 

[PYoder]

Curious as to what airframe - I have never had an alternator with a built-in regulator on any of my 520/550's.

 

[Tom broadhurst]

i haven’t either that’s why i was asking

 

[PYoder]

i haven’t either that’s why i was asking

I wonder if it was an ill-advised modification. I’d put it back to conform with the manual!

 

[TRCsmith]

What kind of alternator? Some of them have a bad reputation for failing early. The B&C are a little more, but they last to TBO and will go another TBO with an overhaul. If it is a Plane-power I am not surprised at the failure. You want top quality accessories if you don’t want the aircraft to leave you stranded on the road.

I've used an alt from Geo metro for over 20 years then replaced with a Honda alt. Auto alt's work fine.

 

[rjones560]

The problem with automotive alternators is the built in regulator. They won’t take the higher temperatures under the cowl generated by air cooled engines. A friend of mine uses a Toyota alternator in his RV6, but he removed the regular from it and installed an external regulator behind the firewall. Automotive alternators will work fine if they have an external regulator behind the firewall. They may work on some aircraft that have smaller power plants and run cooler. It get pretty hot under the cowl of my RV10.