PP alternator voltage/amps fluctuations

[rv8ch]

PP 60Amp, Earthx, GRT EIS 4000 w/hall effect sensor on alternator B-lead, running all lights, etc. Steady state getting these kinds of fluctuations both voltage and current - is this "normal"? I have not yet tested without the flyleds wigwag lights or strobes or position lights (which are awesome, by the way).

[vlittle]

Looks like you have two waveforms with zero cross-correlation. Within each waveform there is strong periodicity.

I would start with the current pulses. If you have no cycling loads, then the Earthx BMS may be cycling. Ask them for more insight into their charging algorithm.

As for the voltage oscillation, any kind of resistance/bad connections in the field circuit can cause this. This is the fundamental problem with internal regulators, and some simple external regulators.

As for being abnormal, what is normal for your aircraft? Is this a new install?

Vern

[rv8ch]

Originally Posted by vlittle

...

As for being abnormal, what is normal for your aircraft? Is this a new install?

Vern

Thanks for the hints Vern. Yes, the aircraft is new, and I see this on all my graphs as saved in my GRT Sport EX EFIS, after it settles down at startup. I assume the startup peak is due to quick charging the battery.

[MCA]

0.1 to 0.2 fluctuation in volts does not seem problematic.

You say strobe lights are on as well as wig-wag , and that should explain the amp fluctuations.

Try turning all lights off and see what happens. The battery could also have a unique charging algorithm.

[Pat Hatch]

You're getting a greater than 10 amp fluctuation which is not normal. The only time I have seen this before it turned out to be a field switch with internal corrosion and the contacts were also corroded. Not sure what the age of your airplane is, but certainly worth a check, easy to swap out your field switch to eliminate that possibility.

[rv8ch]

Powered off all the lights and the current shown from the alternator did go down - no surprise.



Looking at the graphs with everything on (except fuel pump/flaps/trim/AP servos) there seems to be a regular pattern.



I will check with earthx and hartzell (plane power) to get their views.

All the connections seem ok but I have not physically disconnected/reconnected them - which I will do. It's all "new", so there could be an installation error.

[vlittle]

In the olden days (2006) in my 9A, I fixed my externally regulated Vans supplied 35A alternator by rewiring the Alt Field switch to control a relay that connected the Alt B lead directly to the external Voltage Regulator (VR).

This eliminated all of the field wiring, terminals and alt switch from the control loop and gave me rock-solid alternator output and reduced headset noise.

Moral of the story: if your alt field circuit is not perfect, you will have problems. If you have an alternator field switch made by Carling, replace it with a Honeywell and make sure you use the expensive crimp terminals, not the ones from the auto parts store. Digi-Key is your friend.

Hartzell will give you the same advice. My next airplane will use an externally regulated alternator with a sense lead.

V

[EarthX Lithium]

Thank you Mickey for reaching out to us at EarthX with your questions.

The battery has no built-in charger or charging algorithm as suggested that could cause this issue. Based on the supplied graphs of voltage levels, (12-15 volts) it is no different than a lead acid battery.

Based on the supplied trends, the current and voltage are not in sync, so this is not a battery issue and there must be some load on the aircraft.

If it is battery influenced/related issue (any kind of battery) the voltage and current oscillations would be in sync. That is, if the alternator voltage increases, then the current from alternator would also increase because more current would be “pushed” to the battery. As voltage out of alternator decreases, the alternator current would decrease for the battery would supply more current.

[rv8ch]

Originally Posted by EarthX Lithium

...
The battery has no built-in charger or charging algorithm as suggested that could cause this issue. Based on the supplied graphs of voltage levels, (12-15 volts) it is no different than a lead acid battery. ...

Thanks Kathy. I am standing by for an answer from PP/Hartzell to see if they have any hints.

BTW, all my switches are honeywell, except my lights.

[rv8ch]

Following up on this, Plane Power/Hartzell generously sent me a new RMA alternator and I get the exact same behavior. I hesitate to call it a "problem" since the alternator is charging, just doing it in I believe a strange way.

Here's the waveform from yesterday's flight - peak current is 15 amps, lowest is 4 amps. The period seems to be just over 11 seconds, and is very regular. I'm not aware of anything running in the aircraft with a 11-12 second period.



Happy to get any ideas.