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Plane Power -- Fool me once...

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bjdecker

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Alternator+Battery Misbehavior...

...

Started up the aircraft this morning and observed the usual & expected high current ( ~60A) indicating that the alternator was recharging the EarthX ETX 900 after its usual vigorous spinning of my IO-360-A1B6.

Taxi'd out to the run up area, glanced at the AMPs again, and WT*?!?! still showing 55A at 900RPM...That's not right...

Long story longer - taxi'd back to hangar and proceeded to un-cowl, inspect, uninstall Plane Power 99-1012 60A alternator. I replaced the regulator/field brush assembly with a spare (from the first Plane Power alternator failure 2 years ago.). Ran up, and observed normal/expected behavior, put everything back together.

So, I ordered a B&C LX60 + LR-3D regulator and will do the replacement/conversion when I do the next oil change...

I cannot have critical components with a MTBF of < 100 hours.
 
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B & C Alternator/Regulator.

You won’t regret switching to B & C.
Excellent reliability & support from this company.
 
But what did buss voltage do? Did it go way high?

Carl

Hey Carl,

Buss voltage was ~13.9Vdc until I turned the field off, then amps dropped to 0 and volts dropped to ~13.7Vdc. Re-energizing field, current amps went back to 52A and buss volts to 13.9V. Increased RPM to 1700 and amps increased to 65A and volts to 14.1Vdc.

I then turned off the battery master (disconnect the battery from the buss & alternator), volts went >15Vdc and the ALT field breaker popped (Plane Power "feature" - OV protection, crowbar the field.)

At that point I called it quits, and took everything apart.
 
my 60 amp B&C alt is at 1000 hrs and doing fine. I use the old style Concorde battery. I typically only get about 3 yrs use on a Concorde.
 
That's all normal behavior. Including the >15V bus voltage without the battery on the bus. No alternator regulator can keep the bus voltage stable without a battery connected to the bus.
It's the battery that's being weird, not the alternator. The alternator was making 52 Amps. No reason to turn it off.

The field switch should be connected to the main bus, so when you disconnect the battery the alternator field goes offline with it. Otherwise the alternator can't regulate properly and you'll cook the avionics on the bus.
Yes, the OV protection kicks in, but it has a 100ms or so delay. During that time just hope that the avionics are well protected by their own design.

Read this: https://en.wikipedia.org/wiki/Load_dump

And yeah these PP alternators can make a lot more than 60A, you just need a discharged (or damaged) lithium battery in the circuit.

Lenny

Hey Carl,

Buss voltage was ~13.9Vdc until I turned the field off, then amps dropped to 0 and volts dropped to ~13.7Vdc. Re-energizing field, current amps went back to 52A and buss volts to 13.9V. Increased RPM to 1700 and amps increased to 65A and volts to 14.1Vdc.

I then turned off the battery master (disconnect the battery from the buss & alternator), volts went >15Vdc and the ALT field breaker popped (Plane Power "feature" - OV protection, crowbar the field.)

At that point I called it quits, and took everything apart.
 
Hey Carl,

Buss voltage was ~13.9Vdc until I turned the field off, then amps dropped to 0 and volts dropped to ~13.7Vdc. Re-energizing field, current amps went back to 52A and buss volts to 13.9V. Increased RPM to 1700 and amps increased to 65A and volts to 14.1Vdc.

I then turned off the battery master (disconnect the battery from the buss & alternator), volts went >15Vdc and the ALT field breaker popped (Plane Power "feature" - OV protection, crowbar the field.)

At that point I called it quits, and took everything apart.

Not defending the virtue of PP, but if you load that B&C to 55 amps and dump the load off via master it is going to blow the OV too. That voltage will rise in milliseconds with instant release of the load.
 
Have to agree with Lenny here. If the buss voltage was close to 14 volts, the regulator and alternator were doing their job. The alternator can't "force" 55 amps to flow; that only happens if something can and wants to accept it, like a faulty battery.
 
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