Plane Power Alt doing weird stuff...

[HGIC]

when I flew 2RD home from Safford, AZ there was no AMP surge like it has now and the PC680 battery was newly installed during our pre-purchase.

This condition began after we had our A&P install our Smoke System and Supertracks. It sat for a week, not on a tender. I didn't fly it home that night, put in on his charger and when I picked it up that next day, when the alt was turned on the amps went to 55.... and lowered back down to normal within 1-min. We continued to experience this and learned that the newly installed battery was dated 2016 and had been on the shelf for nearly 4-yeas.... so we bought the EarthX

Our checklists, and various POH's I have researched show starting the engine, then turning on the Alt.... open to suggestions here...

[TShort]

I also run an EarthX battery, with B&C alternator.

I start the engine then turn on the alternator.

After cranking, it is normal to see 40-50+ amps for a short time as the battery is recharged.

As someone mentioned above, this is spelled out clearly in the EarthX manual, as it is a common question for them. And gave me concern the first time I saw it!

[HGIC]

also... the VPX shows Volts are normal and the AMPS are being directed to the Battery (both with the new and old battery)

[bjdecker]

Originally Posted by HGIC

also... the VPX shows Volts are normal and the AMPS are being directed to the Battery (both with the new and old battery)

Volts <> Volts
With your VPX or other system, the bus voltage measured will vary depending upon where and when the potential is measured. e.g. With the engine/alternator off with a fresh/charged PC680 battery, you should expect to see a voltage of ~12.2V, until you crank the engine and the volts will drop to 10V or so, and then once the alternator is spinning & turned on, the volts will go to > 14.0V (14.5V)....With an EarthX battery, the resting fully charged voltage is ~13.2V, dropping to 11V during cranking and then rising to 14.5V once the engine/alternator are running.

Charging:
Charging occurs when the Battery is connected to a circuit/bus with a higher potential (voltage) than the battery itself.

The chemistry of the battery, the number of cells in the battery, the internal resistance of the battery, and voltage potential state will determine how much current is drawn (sunk) by the battery.

The C rate of LeadAcid, AGM, Gel, ALC, etc.(e.g. Odyssey PC680) is between .1 and .05C, compared to a C rate of almost 1C for LiFePo4 (EarthX). So you should expect the charging current of an EarthX battery to be quite a bit higher for shorter periods than your PC680.

On Alternators:
Look at the Plane Power spec sheet that came with the alternator. You will notice that the 60 AMP alternator (AL12-EI60) is really capable of producing current >70A following a curve that's proportional to the alternators rotor speed.

Someone asked if this was safe for the equipment. Yes, this is safe, normal, and expected.

Good reading material at https://batteryuniversity.com/learn.

[lr172]

Originally Posted by DanH

At what voltage?



As noted, a lot of amps initially would be expected with a lithium iron battery. As for the lead-acid battery, if the alternator's output voltage is normal, I think it was simply rather dead.

+1

If my alt was pumping out 50 amps for a few minutes after startup and then settled down, I would assume that my lead acid battery was failing and due for replacement. A failing battery often struggles to hold a charge. This is normal for a lithium.

Larry

[HGIC]

Thanks for all the information! Coming from the Cessna world I have a lot to learn and I really appreciate all of your help.

[rv8ch]

Originally Posted by HGIC

...Our checklists, and various POH's I have researched show starting the engine, then turning on the Alt.... open to suggestions here...

Seems people have had good luck with both methods.

[airtractor8]

Our checklists, and various POH's I have researched show starting the engine, then turning on the Alt.... open to suggestions here...

This (similar) alternator and internal regulator system was used in small 4 cylinder cars in the 80's (Suzuki Samurai & others). I dont know of any car owners that turned the alternator on AFTER starting the car do you? A Lycoming with the same system is no different. Save yourself some grief and turn the Alternator "excitement" (internally regulated alternator) power on when you turn the master on and BEFORE you start the engine. Easy

[Paul 5r4]

For a short while I was turning on only the battery side of master to start the engine then turning on the alt. I had read this sends a couple more amps to the starter. Soon after my alt failed. I have to idea if it was related. Then I read something in a post here on VAF for a reason NOT to leave alternator off during start up and it sounded good so I stopped and went back to what I had always done. I don't remember what the posters reason was to keep alt on during starts. Anyway just my experience.

[OKAV8r]

What engine RPM are you energizing the alternator at?
My recommendation is to start the engine with alternator "off",
then, after engine is running smoothly and oil pressure has stabilized, pull the throttle to idle and THEN energize the alternator.
Two good things result:
1) Less stress on alternator belt
2) alternator isn't spinning fast enough to spike overvolt, or produce maximum output.
After the alternator has been brought online, then ease the engine rpm up until you see that the regulator (alternator controller) is maintaining proper buss voltage.