Volts and pressure

[caymancraig]

My voltage runs from 12.4 to 11.8 during flight. The alternator is charging. Is this normal voltage? I ran the battery COMPLETELY dead twice and it seemed to recharge okay. Regular Odessy as recommended by Sonex.
Next up is oil pressure. I polished the two plungers and it seems to be settling in. 74lbs at startup, 38 lbs at 180 degrees, and 30 lbs at 200 degrees. I added two washers under the rear spring and that raised it to the current 30 lbs. My CHT and EGT's are staying below the yellow range if I careful with climb. I understand the CHT and EGT's will improve with time. (only 4 flights right now).

Guess I'm looking for some reinforcement right now, lol

Thanks all,
Craig Mock

[gammaxy]

Are you saying your voltage decreases from 12.4 to 11.8 during flight? I would expect it to typically increase for the first 10-20 minutes of flight then plateau around 13 volts.

Are you sure your oil pressure is calibrated? I remember not being 100% sure if my settings in the MGL Stratomaster were correct for my VDO sender. I double-checked the sender by connecting it to my air compressor. Others recommend comparing to a mechanical sender which seems like a good idea, but I haven't personally done so. 30 seems low to me. I typically see around 50psi in flight (probably closer to 40-45 in the summer with 200F oil temps). It's easy to imagine you have it mis-calibrated by 10psi and are actually right where Sonex recommends (40-50).

[Sonex1414]

If you are reading a high of 12.4 volts, that is usually battery voltage. When running WOT you should see voltage above battery voltage by 2-3 volts. I have seen 15 volts indicated at 3500 RPM. I assume that you have an AeroVee. The faster the engine turns the more volts. Start with testing the regulator then the alternator. Remember the alternator puts out AC volts.

Good luck!
Tom

[radfordc]

You might start by checking your battery connections. When I was having what I thought was regulator problems it turned out to be a loose battery wire.

[caymancraig]

I added an old fashion mechanical oil pressure gauge and it reads 1 or 2 lbs higher than my Dynon electronic gauge.

[mike.smith]

When I saw those voltages the stator was coming loose and was self destructing. Not saying that's happening, but it's possible.

[NWade]

Also: What are you using for a voltmeter? Is it built into another instrument on your panel (like a radio or EFIS)? If so, its likely that you've got a circuit-breaker between the battery and the device displaying volts. Low-amperage push-pull CBs tend to cause a noticeable voltage-drop (as much as 1.5 volts for CBs under 2a). So the reading you're getting may not actually be the voltage the battery is putting out. It still sounds low even if you add 1v to your readings, but I wanted to make sure you're thinking about all possible sources when troubleshooting.

Good luck!

--Noel

[Sonex1517]

When I had this issue it was a bad voltage regulator. YMMV


Robbie Culver
Sonex 1517
Chicagoland
N1517S