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tx_jayhawk

Well Known Member
I have an interesting voltage problem I am hoping to get some perspective on. Recently, my main bus voltage is in the 13 volt range, as opposed to the 14 voltage range it previously was operating at. The alternator does appear to be working (turning off the alt field in flight drops the voltage much further and produces a large current drain on the battery), but for whatever reason the bus voltage is low. It's like the internal regulator in the PP is only trying to charge it to a lower voltage. I've had the Odyssey battery tested two separate times and it appears to be good. The bus ranges from 12.8 to 13.2. If the battery were bad, I'm assuming the bus voltage would be lower than the ~13.

I've followed the PP troubleshooting, and all connections appear to be good with proper voltage from the field and B lead.

Any thoughts?

THanks,
Scott
 
Diode?

I wonder if you lost a diode, if you loose one or two it will still produce power, but not full capacity. You may still see normal voltage but if you load it it will drop off. Load it down with landing lights, seat heaters or what have you, it should hold pretty steady. If it doesn't have someone test it.
Also you may want to check and tighten the engine grounds.
Tim
 
Just had this discussion with PP after I had a spun bearing with my PP 60 amp alternator. Start by measuring the voltage at the battery terminals and the engine turning 23-2400 rpm(preferably in flight, using well secured leads from the battery terminals to an accurate voltmeter at your side). You should see 14.3-14.4 volts if the alternator is working properly. If that is what you see, it is not an alternator problem. Start looking for poor connections. poor ground, inaccurate panel voltmeter. If you see 13.x volts, PP can repair and turn around your alternator in a day.

Jim Berry
RV-10
 
I had a similar problem. Not that low though. I cleaned all the connections on the shunt, master relay, ANL-60 (fuseable link) battery terminals, engine ground. Better. Now showing 14.1-.3. My thought is that that one drip of oil from the dipstick that occasionally drops when I check the oil was causing the problem. I promise to be more careful.
 
Good idea to clean all the connections, however oil will not cause or create a bad connection, in fact just the opposite, it helps to prevent corrosion.
 
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